Engineering Articles
Longer-form technical writing, published as it is finished and revised as field experience corrects it. Every entry carries its published and updated dates.
212 entries
PLC Architecture
How a programmable logic controller is physically organized: the chassis, backplane, processor, I/O modules, remote racks, and what those choices mean for wiring, expansion, and failure.
8 min readUpdated Sep 5, 2026
Control Power Supplies
Sizing the 24 VDC supplies that run a controller and its field devices, separating loads that should not share a supply, and keeping the controller alive through a power event.
8 min readUpdated Sep 5, 2026
IEC 61131-3
The standard behind PLC programming languages: the five languages, the common elements of data types, variables, and program organization units, what conformance actually means, and how the standard shows up in real platforms.
9 min readUpdated Sep 5, 2026
Structured Text
The text language of IEC 61131-3: syntax, control structures, how it fits alongside ladder, the conventions that keep it readable for the next person, and the mistakes that make structured text a liability in a plant that troubleshoots online.
10 min readUpdated Sep 5, 2026
Function Block Diagram
The graphical data-flow language of IEC 61131-3: how blocks, pins, and wires work, execution order, where FBD beats ladder and structured text, building reusable equipment blocks, and the habits that keep a diagram readable.
9 min readUpdated Sep 5, 2026
State Machines in PLC Programs
Writing sequences as explicit states instead of tangled interlock chains: what a state is, how transitions are written, the pattern in structured text and in ladder, publishing the state to the HMI, and the failure handling every state machine needs.
11 min readUpdated Sep 5, 2026
Program Organization
Structuring a controller program so that someone else can maintain it: a layout that follows the plant, one routine per job, standard device blocks, I/O mapped in one place, a fixed execution order, naming that means something, and comments that say why.
10 min readUpdated Sep 5, 2026
Alarms in the Controller
Generating alarm conditions in the controller rather than in the graphics: why the PLC should own the alarm state, a standard alarm block with setpoints, deadband, and delays, equipment alarms, and packing alarm bits for SCADA.
9 min readUpdated Sep 5, 2026
Sequential Function Chart
The IEC 61131-3 language for sequences: steps, transitions, actions and their qualifiers, alternative and simultaneous branches, where it fits in water and wastewater, and the rules that keep a chart from sticking in a step.
9 min readUpdated Sep 5, 2026
Modicon M340
Field notes on the Schneider Electric Modicon M340, a rack-based mid-range controller common in water plants: rack and CPU layout, X80 I/O, memory card behavior, Ethernet and serial communications, programming in Control Expert, and what to check on site.
8 min readUpdated Sep 5, 2026
Modicon M580
Field notes on the Schneider Electric Modicon M580, the Ethernet-backplane controller at the top of the range: remote I/O drops on a ring, hot standby CPUs, built-in security features, the networks it defines, Quantum migration, and what to check on site.
9 min readUpdated Sep 5, 2026
Control Expert
Field notes on Control Expert, the Schneider Electric engineering software for the Modicon M340 and M580: project structure, the five languages and derived function blocks, versions and files, online changes, upload information, and security settings.
8 min readUpdated Sep 5, 2026
Unity Pro
Field notes on Unity Pro, the earlier name of Control Expert and the software behind most installed Modicon M340, Quantum, and Premium applications: versions, moving projects to Control Expert, keeping an old version alive, and the Concept and PL7 originals.
7 min readUpdated Sep 5, 2026
ControlLogix
Field notes on the Rockwell Automation ControlLogix, the chassis-based controller of larger water plants: chassis and modules, tag-based memory and tasks, EtherNet/IP and older networks, controller redundancy, version matching, and what to check on site.
9 min readUpdated Sep 5, 2026
CompactLogix
Field notes on the Rockwell Automation CompactLogix, the smaller Logix controller behind most lift stations and small plants: families and I/O, the two Ethernet ports, what it shares with ControlLogix and what it lacks, and what to check on site.
8 min readUpdated Sep 5, 2026
Studio 5000
Field notes on Studio 5000, the Rockwell Automation software for ControlLogix and CompactLogix: the version-to-firmware rule, side-by-side installs, project files, add-on instructions, online editing, documentation in the controller, source protection.
8 min readUpdated Sep 5, 2026
Siemens
Field notes on Siemens controllers in water and wastewater: the S7-1200 and S7-1500 with TIA Portal, the older S7-300 and S7-400, PROFINET and PROFIBUS, the block model and memory cards, protection levels, and why it arrives inside packaged equipment.
8 min readUpdated Sep 5, 2026
AutomationDirect
Field notes on AutomationDirect controllers in water and wastewater: the Productivity, Do-more and BRX, and CLICK families with free software, the legacy DirectLOGIC line, Modbus and EtherNet/IP support, what they suit, and what to check on site.
8 min readUpdated Sep 5, 2026
Legacy Systems
Keeping older controllers running and planning a migration: the families still found in water plants, the risks that grow each year, software to keep alive, batteries and memory, tested spares, the security problem, and a migration the plant can survive.
9 min readUpdated Sep 5, 2026
Engineering Units
Choosing and documenting the units a tag carries: where the unit is decided, how it flows from transmitter range to controller scaling to screen and historian, the conventions used in water and wastewater, and the mismatches that put a wrong number on screen.
7 min readUpdated Sep 5, 2026
Remote I/O
Extending controller I/O to another panel or another site over a network: the adapter and the rack, the update rate and what it costs, what the outputs do when the link fails, the difference between remote I/O and a remote controller, and the wiring, addressing, and diagnostics that make it dependable.
9 min readUpdated Sep 5, 2026
ISA-101: Human Machine Interfaces
What the ISA-101 standard for human machine interfaces covers, its lifecycle from philosophy to maintenance, the display hierarchy, and what adopting it changes on a project.
8 min readUpdated Sep 5, 2026
SCADA Architecture
The parts of a SCADA system and how data moves between them: I/O servers, the tag database, clients, the historian, the alarm server, and the topologies from a single panel PC to a redundant, distributed plant.
9 min readUpdated Sep 5, 2026
Historians
What a process historian does that a database does not, how data gets into it, how compression and retrieval work, how to size and keep it, and the settings that quietly throw data away.
8 min readUpdated Sep 5, 2026
SCADA Redundancy
What redundant SCADA servers protect against and what they do not, how failover works for tags, alarms, history, and clients, the network and controller layers beneath it, and why an untested failover is not redundancy.
8 min readUpdated Sep 5, 2026
The Alarm Philosophy
The document that decides what is allowed to be an alarm: the definition, the criteria, the priorities and their meaning, the performance targets, the handling rules, and who owns it. Under ISA-18.2 it comes first.
9 min readUpdated Sep 5, 2026
Alarm Priority
How to assign alarm priorities that operators trust: a consequence-and-time matrix, three or four levels, the target distribution from ISA-18.2 and EEMUA 191, and the mistakes that make every alarm high.
9 min readUpdated Sep 5, 2026
Alarm Floods
What an alarm flood is, why it happens at exactly the wrong moment, the ISA-18.2 rate targets, and the design measures that keep a power failure or a communication loss from burying the one alarm that matters.
10 min readUpdated Sep 5, 2026
Alarm Notification and Callout
Getting the alarm to the person on call when no one is watching the screen: notification paths, escalation, acknowledgment from the field, which alarms qualify, and the failure modes that leave a station in high level with nobody paged.
10 min readUpdated Sep 5, 2026
HMI Faceplates
The pop-up that controls one device: what a pump, valve, or loop faceplate must show, the mode and command layout, interlock and permissive display, security by role, and building faceplates from a standard object so every device behaves the same.
10 min readUpdated Sep 5, 2026
Trends on the HMI
Trend displays that answer questions: embedded sparklines on process displays, pre-configured trend groups, the axes and time spans that make a trend readable, and the difference between a trend for operating and a trend for investigating.
9 min readUpdated Sep 5, 2026
Alarm Indication on the HMI
How an alarm looks and sounds on the operator screen: the ISA-101 and ISA-18.2 rules for color, shape, and blink, the alarm banner and summary, acknowledgment behavior, navigation to the alarm, and indication that survives colorblindness and a noisy control room.
10 min readUpdated Sep 5, 2026
HMI Navigation
How operators move through the displays: the display hierarchy from overview to detail, a fixed navigation bar with area alarm indication, one-click paths from an alarm to the device, the rules that keep any display within two clicks, and what to leave out.
9 min readUpdated Sep 5, 2026
Historian Architecture
How process history is collected, stored, and served: the collector, the archive, and the client layers, where the historian sits relative to SCADA and the DMZ, single-server and tiered designs for a utility, the store-and-forward buffer that survives outages, and the sizing that decides how many years fit on a disk.
9 min readUpdated Sep 5, 2026
Historian Data Collection
Deciding what the historian stores and how often: polled versus exception collection, the deadband per tag, rates for control loops, levels, totals, and compliance values, timestamps at the source, quality codes, calculated tags, and the tag list review that keeps a historian from filling with noise and missing what matters.
9 min readUpdated Sep 5, 2026
Historian Compression
How historians store years of data on a disk: exception deadbands at the collector, swinging door compression at the archive, what each discards and what it keeps, the settings that turn a trend into a staircase, lossless alternatives, and how to check that the compressed data still tells the truth.
8 min readUpdated Sep 5, 2026
SCADA Servers
What the servers in a SCADA system do and what a utility should expect of them: the I/O, alarm, historian, and client roles, physical versus virtual, redundancy, sizing, placement, backup, patching, licensing, and monitoring.
10 min readUpdated Sep 5, 2026
SCADA Clients
The workstations, browsers, and mobile devices operators use to see and control the system: thick, thin, web, and mobile clients, roles and permissions, where control is allowed from, workstation design, session policy, licensing, and failover behavior.
9 min readUpdated Sep 5, 2026
Alarm Servers
The part of SCADA that turns a condition into an alarm and manages its life: where detection happens, the alarm state machine, priority, deadband and delays, acknowledgment across clients, the journal, notification, redundancy, timestamps, and flood behavior.
10 min readUpdated Sep 5, 2026
Color in HMI Design
How color is used on a high performance HMI: a gray palette for normal operation so that color means something, alarm colors reserved by priority, equipment state by fill and text rather than red and green, color-blind safe choices, and the palette table.
9 min readUpdated Sep 5, 2026
Situational Awareness
Designing displays so an operator knows what is happening, what it means, and what comes next: the three levels of awareness, the display hierarchy, analog indicators with normal ranges, embedded trends, time-to-limit predictions, and a test for any display.
10 min readUpdated Sep 5, 2026
Alarm Shelving
The operator tool for temporarily silencing a nuisance alarm: what shelving is and is not, the rules a philosophy sets, who may shelve what and for how long, automatic unshelving, the shelved list, the record, and how to implement it on any platform.
8 min readUpdated Sep 5, 2026
Alarm Suppression
Suppressing alarms by design: state-based logic that removes alarms that mean nothing in the current state, parent-child logic that stops a flood at its source, out-of-service suppression for maintenance, the rules that keep it safe, and how to test it.
9 min readUpdated Sep 5, 2026
Server Failure
How SCADA servers fail and what to do when one does: failure modes from a full disk to a dead hypervisor host, what the plant experiences with and without redundancy, the recovery sequence from restore to alarm verification, and the monitoring that warns.
9 min readUpdated Sep 5, 2026
Historian Problems
How a historian goes wrong and how to find each fault: gaps, wrong values, detail never stored, disks that fill, slow queries, backfill that never arrives, and unreadable archives, with the collector, queue, configuration, and storage checks that locate it.
9 min readUpdated Sep 5, 2026
Long-Term Storage
Keeping historian data for years: a retention policy by data class that follows the record rules, tiered storage from online to offline copies, downsampling, archive management, exports that outlive the historian, and the annual proof that old data reads.
9 min readUpdated Sep 5, 2026
SQL Integration
Connecting SCADA and historian data to relational databases: why a utility does it, the methods, a schema that handles time series, the query patterns for totals and reports, the mistakes that flood a database or stall a server, and security.
10 min readUpdated Sep 5, 2026
VTScada
Field notes on VTScada, the Trihedral platform widely used by municipal water utilities: the all-in-one design with historian, alarm notification, and thin clients built in, server redundancy, application versioning, telemetry drivers, and licensing by tags.
8 min readUpdated Sep 5, 2026
Ignition
Field notes on Ignition from Inductive Automation: gateway and modules, unlimited licensing per server, Perspective and Vision clients, the SQL-based historian, Python scripting, redundancy, Edge for small sites, and what to decide before building on it.
8 min readUpdated Sep 5, 2026
GE iFIX
Field notes on iFIX, the long-established SCADA from the Intellution and GE lineage now sold by GE Vernova: SCADA nodes and the process database, I/O drivers, view and web clients, the Proficy Historian, enhanced failover, scripting, and licensing by points.
8 min readUpdated Sep 5, 2026
AVEVA
Field notes on the AVEVA operations software family, formerly Wonderware: InTouch HMI, System Platform and its object model, the Historian, Plant SCADA from the Citect lineage, and AVEVA Edge. Which product does what, and what to check on site.
8 min readUpdated Sep 5, 2026
Rockwell FactoryTalk
Field notes on the Rockwell Automation FactoryTalk family: View Site Edition and Machine Edition, the directory, Linx with direct controller tag access, device-based Alarms and Events, the PI-based Historian, ViewPoint and Optix, redundancy, and site checks.
8 min readUpdated Sep 5, 2026
Schneider SCADA
Field notes on Schneider Electric SCADA for water: EcoStruxure Geo SCADA Expert, formerly ClearSCADA, the telemetry platform built around DNP3 events, an object database, and hot standby servers, with SCADAPack RTUs, and how it relates to the AVEVA products.
8 min readUpdated Sep 5, 2026
Other Platforms
The SCADA and HMI products a water utility may meet beyond the common ones: Siemens WinCC, distributed control systems, independent SCADA products, hosted lift station monitoring, and open-source tools, and the questions that decide whether one belongs.
8 min readUpdated Sep 5, 2026
Turbidity Measurement
Nephelometric turbidimeters for filter effluent and raw water: how 90-degree scattering is measured, the methods and the NTU, low-range versus high-range instruments, bubbles and the debubbler, formazin calibration and verification standards, and the compliance record the instrument exists to produce.
11 min readUpdated Sep 5, 2026
Calibration Procedures
How a utility calibrates its instruments consistently: the as-found and as-left discipline, tolerance from the loop rather than the data sheet, the reference standard and its traceability, the five-point check with hysteresis, adjusting only when needed, intervals set from history, and the procedure written once per instrument type.
9 min readUpdated Sep 5, 2026
Calibration Documentation
The records a calibration program produces and what each is for: the calibration certificate per event, the instrument history, the reference standard file, the schedule, the tolerance and interval register, and how the records are organized so a regulator, an auditor, or the next technician can find what they need.
8 min readUpdated Sep 5, 2026
Impulse Lines
The tubing between the process tap and the pressure or DP transmitter, and everything that goes wrong in it: slope and routing for liquid and gas, elevation head and how to correct for it, air and condensate, blocking and manifold valves, freezing, plugging on dirty service, and the diaphragm seal alternative.
9 min readUpdated Sep 5, 2026
Flowmeter Installation
The installation rules that decide whether a flowmeter reads correctly: straight run by meter type, keeping the pipe full, orientation, velocity range, grounding for magnetic meters, isolation and access, and the commissioning checks that prove the meter.
10 min readUpdated Sep 5, 2026
Differential Pressure Level
Measuring level in a closed or pressurized vessel with a DP transmitter: high and low side connections, dry legs and wet legs, zero suppression and elevation, the range calculation with a worked example, remote seals, and the density dependence.
10 min readUpdated Sep 5, 2026
Pressure Transmitter Installation
Where and how to install a pressure transmitter so it reads the process and not its own plumbing: tap location, mounting above or below the tap, isolation and bleed valves, line slope, pulsation, elevation, freeze protection, seals, vibration, and sun.
10 min readUpdated Sep 5, 2026
Pressure Calibration
What calibrating a pressure transmitter means: as-found and as-left, the five-point test and hysteresis, tolerance and the reference standard, sensor trim versus output trim versus reranging on a smart transmitter, gauge versus absolute, and intervals.
10 min readUpdated Sep 5, 2026
Ammonia Analyzers
Online ammonia measurement in water and wastewater: ion-selective probes, gas-sensing electrodes, and wet-chemistry analyzers, what each is good for, the interferences that decide accuracy, and the maintenance and calibration it demands.
9 min readUpdated Sep 5, 2026
Nitrate Analyzers
Online nitrate measurement: ultraviolet absorbance probes and analyzers, ion-selective electrodes, and wet chemistry, the interferences from organics, turbidity, and chloride, the uses in denitrification and source monitoring, and maintenance.
8 min readUpdated Sep 5, 2026
Digital Signals
Discrete signals between instruments and controllers: dry and wetted contacts, sinking and sourcing transistor outputs, two-wire sensor leakage, NAMUR sensors with wire-break detection, contact ratings at low current, and wiring conventions.
8 min readUpdated Sep 5, 2026
Signal Isolation
Isolating analog signals: loop isolators and their variants, splitters that feed two receivers, converters, the common-mode problem isolation solves, ratings, accuracy and response costs, and when an isolated input module makes the isolator unnecessary.
8 min readUpdated Sep 5, 2026
Short-Circuit Current Rating (SCCR)
What a control panel’s short-circuit current rating means, how it is determined under UL 508A, why the NEC requires it on the label, and why the number is usually smaller than people expect.
9 min readUpdated Sep 5, 2026
Enclosure Selection
Choosing the box: NEMA and UL 50 type ratings, materials for corrosive and outdoor sites, sizing for heat and wire bending space, and the details at the conduit entries and the door that decide whether the rating survives installation.
8 min readUpdated Sep 5, 2026
Enclosure Heat Calculations
Estimating the temperature inside a control panel from the power its contents dissipate and the surface that carries it out, what to do when the answer is too hot, and why drives change everything.
8 min readUpdated Sep 5, 2026
Component Layout
Arranging a panel so it is safe to work in, cool enough to run, quiet enough for its signals, and possible to modify: power and control separation, heat, wireways, terminals, and the working space rules.
8 min readUpdated Sep 5, 2026
Hand-Off-Auto Selectors
What each position of an HOA selector does, how it is wired into the starter circuit, which protections must survive Hand, what the controller should see, and the mistakes that let a pump run with nobody watching.
7 min readUpdated Sep 5, 2026
Panel Power Supplies
The 24 V DC supply behind everything in a modern panel: sizing with real inrush and duty, single versus redundant with diode modules, how a switch-mode supply behaves under a short, distribution and fusing per branch, monitoring, and the failure modes that take out a whole panel at once.
9 min readUpdated Sep 5, 2026
Control Relays
The interposing and logic relays in a control panel: why a controller output drives a relay instead of a starter coil, contact ratings and the difference between resistive and inductive loads, coil suppression, ice cube relays versus terminal relays versus solid-state, and the failure modes that make a relay the first suspect in a dead circuit.
8 min readUpdated Sep 5, 2026
Terminal Blocks
The point where field wiring meets the panel: screw, spring, and push-in terminals, ratings and the UL 1059 groups, fused and disconnect terminals for instrument loops, grounding terminals, multi-level blocks, jumpers and marking, and the layout that makes a loop check or a field change a five-minute job.
8 min readUpdated Sep 5, 2026
UPS for Control Panels
Keeping the controller, the radio, and the SCADA server alive through an outage: AC and DC UPS types, what to put on the UPS and what not to, sizing for runtime and inrush, the battery as a maintenance item, the alarms a UPS must provide, and what happens when the UPS is the thing that fails.
8 min readUpdated Sep 5, 2026
Noise Problems
Electrical noise as a panel problem: the four ways it couples, the design features that keep it out, the sources people forget such as unsuppressed coils and unbonded doors, and the sequence for finding where noise gets into a panel that should be clean.
10 min readUpdated Sep 5, 2026
NFPA 70 and the Control Panel
The National Electrical Code inside an industrial control panel: Article 409 and the listing it points to, the short-circuit current rating, overcurrent protection for control circuits, grounding and bonding, working space, and what an inspector asks.
9 min readUpdated Sep 5, 2026
UL 698A
Industrial control panels for hazardous locations: what UL 698A adds to UL 508A, a panel in a classified area or a safe-area panel with intrinsically safe circuits, barriers and isolators, the control drawing, and where utilities meet classified areas.
8 min readUpdated Sep 5, 2026
Wireways
Panel wireway design: fill limits and the space terminations need, separating power, control, and signal wiring, routing around heat and drives, sizing rules, the cases where wireway is the wrong choice, and the habits that keep a panel serviceable.
7 min readUpdated Sep 5, 2026
Terminals
Designing the terminal strips of a control panel: grouping by voltage and function, numbering that matches the drawings, fused and disconnect terminals for instrument loops, shield and ground terminals, spares, ferrules and torque, and the terminal schedule.
7 min readUpdated Sep 5, 2026
Network Switches
Selecting and installing the Ethernet switch in a control panel: managed against unmanaged, industrial ratings and DIN rail mounting, ports and media including fiber, ring protocols, power and grounding, and the configuration documented with the panel.
8 min readUpdated Sep 5, 2026
Failed Power Supplies
Diagnosing the 24 volt supply in a control panel: dead, low, noisy, or cycling, a failed supply against an overloaded one, loads that grew, heat and capacitor aging, redundant supplies, sag on the input, and what to specify so the next failure is an alarm.
8 min readUpdated Sep 5, 2026
Relay Problems
Diagnosing control relays in a panel: contacts that do not make or that weld, coils that fail or chatter, drop-out on sag, interposing relays on controller outputs, loads that burn contacts, suppression, sockets, and replacing against fixing the cause.
7 min readUpdated Sep 5, 2026
PLC Power
Powering the controller section of a panel: the control transformer and 24 volt supplies, separating controller power from field I/O power, sizing with margin, the UPS and what rides through, protection and monitoring, the DC ground, and restart sequencing.
8 min readUpdated Sep 5, 2026
Panel I/O
Arranging the I/O in a controller panel: module types for the field devices, sinking, sourcing, and isolated inputs, fused and relay outputs, the path from field terminal to module, spare capacity, and addressing that follows the I/O list.
8 min readUpdated Sep 5, 2026
Relays in the PLC Panel
The relays a controller panel needs and why: interposing relays between outputs and loads, input relays for high-voltage and remote signals, isolation and safety relays, monitoring relays, coil and contact selection, and keeping logic out of relays.
7 min readUpdated Sep 5, 2026
Isolation
Isolating the controller from the field: why grounds differ and what that does to signals, signal isolators and isolated channels, isolation transformers and their limits, relays as isolation, fiber as the ultimate isolator, and when isolation is worth it.
8 min readUpdated Sep 5, 2026
Panel Surge Protection
Surge protection of a controller panel as a system: a single entrance and the ground bar it lands on, staged protection on the power, protectors on every loop and data line that leaves the building, the radio feed, layout, and the checklist after a strike.
8 min readUpdated Sep 5, 2026
Panel Networking
The network inside a controller panel: which networks exist and how they are kept apart, where the switch sits, copper patching and fiber entry, the radio or cellular router as a panel component, cable management, shield grounding, and labeling.
7 min readUpdated Sep 5, 2026
Duplex Pump Panels
The duplex control panel: two pumps on one wet well and the sections every duplex panel contains, from power and starters through level control, alternation, hand-off-auto, alarms, and the backup float circuit to telemetry, with the failure responses.
9 min readUpdated Sep 5, 2026
Triplex Pump Panels
The triplex control panel: three pumps on one wet well, the alternation schemes that keep three pumps evenly used, staging levels and standby logic, power, drives and their coordination, the backup circuit for three pumps, and what a duplex never decides.
8 min readUpdated Sep 5, 2026
Alternation
Pump alternation at the panel level: what it is for, the alternator relay against controller logic, schemes from alternate-every-cycle to runtime balancing, manual lead selection, skipping a failed pump, alternation in the backup circuit, and the tests.
7 min readUpdated Sep 5, 2026
Lift Station Backup Control
How a lift station keeps pumping when the transmitter, the PLC, or the SCADA link is gone: float backup logic, the control transfer relay, redundant-off protection, and how to test it with the controller actually dead.
12 min readUpdated Sep 5, 2026
Aeration
Aeration in drinking water treatment: stripping carbon dioxide, hydrogen sulfide, radon, and volatile organics, and oxidizing iron and manganese ahead of filtration. The aerator types, what each needs from the control system, the pH shift, and the interlocks.
9 min readUpdated Sep 5, 2026
Filtration
Controlling gravity and pressure filters: effluent rate and level control, head loss and turbidity on every filter, the backwash triggers and sequence, filter-to-waste and ripening, the turbidity rules that filter monitoring answers to, and the operator view.
11 min readUpdated Sep 5, 2026
Finished Water Storage
Storage inside the plant: the clearwell that provides contact time and high service suction, backwash supply tanks, and how their levels drive production and pumping. The contact time calculation and the minimum level it demands, water age, and alarms.
9 min readUpdated Sep 5, 2026
High Service Pumps
The pumps that carry finished water into distribution: types, the pump curve against the system curve, best efficiency point, the affinity laws and where a drive pays, parallel operation, valves, protection, and the efficiency monitoring that shows wear.
11 min readUpdated Sep 5, 2026
Pump Sequencing for Storage
Sequencing the pumps that fill and draw from storage: staging on level bands, rotating wells and sources for even use and water quality, time-of-day and demand-based scheduling, and the records that show the sequence is doing its job.
8 min readUpdated Sep 5, 2026
Reverse Osmosis
Reverse osmosis from the controls side: what the skid contains, the instruments that matter, the numbers an operator watches, recovery, rejection, normalized permeate flow, and the trends that say when the membranes need cleaning or replacement.
10 min readUpdated Sep 5, 2026
Nanofiltration
Nanofiltration from the controls side: how it differs from reverse osmosis in pressure, recovery, and what it removes, the softening and color removal applications where it dominates, and trends that are shared with reverse osmosis and the ones that differ.
8 min readUpdated Sep 5, 2026
Clean-in-Place
Cleaning membranes in place: the triggers from the normalized trends, the low pH clean for scale and the high pH clean for organics and biofouling, the sequence of flush, heat, recirculate, soak, and rinse, and how automation makes cleaning repeatable.
9 min readUpdated Sep 5, 2026
Membrane Feed Pumps
The high-pressure feed pumps of a membrane plant: multistage centrifugal pumps on drives, the pressure ramp that protects the elements, suction protection and the cartridge filters ahead of them, and the maintenance that the trends point to.
8 min readUpdated Sep 5, 2026
Concentrate Systems
Handling the concentrate a membrane plant produces: the concentrate valve and the recovery it sets, flow and quality monitoring for the permit, the disposal routes, surface discharge, sewer, and the alarms and records a concentrate permit expects.
8 min readUpdated Sep 5, 2026
Biological Treatment
The biological process from the controls side: activated sludge and its common forms, conventional, extended aeration, oxidation ditch, sequencing batch reactor, and membrane bioreactor, and the alarms that give an operator time.
9 min readUpdated Sep 5, 2026
Chemical Systems in Wastewater Treatment
The chemical feeds of a wastewater plant and their controls: coagulants for phosphorus, polymer for thickening and dewatering, hypochlorite and sulfite for disinfection and dechlorination, and the alarms that keep the plant in its permit.
9 min readUpdated Sep 5, 2026
Effluent Disinfection
Disinfecting the effluent and proving it: chlorination with contact time and residual control, dechlorination with sulfite controlled by ORP or a residual analyzer, ultraviolet systems with dose control from flow, and the records the discharge report needs.
9 min readUpdated Sep 5, 2026
Effluent
Effluent from the controls side: the flow measurement the permit is built on, the composite samplers it paces, the parameters measured online, flow, pH, dissolved oxygen, residual, turbidity, and the data integrity that makes the record defensible.
8 min readUpdated Sep 5, 2026
Residuals
Solids handling from the controls side: thickening by gravity, flotation, or drum, aerobic and anaerobic digestion with their temperature, mixing, and gas systems, dewatering by belt press, centrifuge, and the records that biosolids regulation requires.
9 min readUpdated Sep 5, 2026
IEC 62443
The international standard series for industrial automation and control system security: how it is organized, what security levels and foundational requirements mean, and how a utility or integrator actually uses it.
11 min readUpdated Sep 5, 2026
Zones and Conduits
The IEC 62443 way to segment a control system: grouping assets into zones with a shared security level, inventorying every conduit between them, and turning the drawing into firewall rules. With a worked water utility example.
12 min readUpdated Sep 5, 2026
Industrial DMZ Design
The buffer zone between the business network and the control system: what goes in it, the no-direct-path rule, push-not-pull data flows, the firewall pair, and the services a utility actually needs to place there.
10 min readUpdated Sep 5, 2026
OT Risk Assessment
Ranking what could go wrong in a control system and what it would cost: the consequence-first method for utilities, the assets and scenarios to list, likelihood without pretending to know it, the risk matrix, and turning the ranked list into a work plan.
10 min readUpdated Sep 5, 2026
Firewall Rule Design
Writing the rule set for a control network boundary: default deny, one rule per conduit with its reason, hosts not subnets, protocol and port and function, direction and initiator, logging on every rule, and the review that removes forgotten rules.
9 min readUpdated Sep 5, 2026
Server Hardening
Reducing what an attacker can do with a SCADA server: a baseline from the vendor guide and a benchmark, unused services removed, the host firewall on, application allowlisting, controlled media, separate administrator accounts, and logs sent off the box.
10 min readUpdated Sep 5, 2026
User Accounts and Roles
Who can do what on the SCADA and how it is enforced: roles from view-only to administrator and their permission matrix, individual accounts including the operator console, service and vendor accounts, same-day offboarding, and the quarterly review.
9 min readUpdated Sep 5, 2026
Patch Management
Applying updates to SCADA servers and clients without breaking the plant: vendor qualification, a monthly cycle with a test system, priority from the exposed edge inward, backups and rollback, emergency patches, and handling software that cannot be patched.
9 min readUpdated Sep 5, 2026
Historian Security
The historian is the most connected server in a control system and the most exposed: giving the office, reports, and the cloud the data they need without a path to the plant, with a collector in the control zone, a replica in the DMZ, and one-way flow.
9 min readUpdated Sep 5, 2026
Third-Party Software
Everything on a control system machine that is not the SCADA: drivers, databases, runtimes, reporting tools, agents, remote support utilities. Why each is an attack surface, the inventory and approved list, rules for installs, and removing what is unused.
8 min readUpdated Sep 5, 2026
Shared Account Problems
Why the shared operator login, the vendor account everyone knows, and the single PLC password are the weakest point in most utilities: no accountability, no offboarding, no detection. Containing what cannot be avoided and migrating the rest.
8 min readUpdated Sep 5, 2026
Password Policy for OT
A password policy that fits a control system rather than an office: length over complexity, rotation on events, screening against breached lists, multi-factor authentication, no lockouts that take control from an operator, and unique vaulted device passwords.
8 min readUpdated Sep 5, 2026
Credential Storage
Where the passwords and keys of a control system are kept: a vault with individual access and a log, break-glass copies in a safe, platform credential stores for service accounts, and the places they must not be, from spreadsheets to project files.
8 min readUpdated Sep 5, 2026
Security Program Basics
What a control system security program is for a utility that has never had one: a named owner, an inventory, a risk assessment, a few policies, baseline controls, training, vendor rules, an exercised incident plan, and a first-year plan for a small staff.
10 min readUpdated Sep 5, 2026
SCADA Backups
What a SCADA backup must contain to bring a system back: the project export, an image of each server, the databases, historian archives, licenses, certificates, scripts, and network device configurations, with frequency, retention, and the restore procedure.
9 min readUpdated Sep 5, 2026
Backup Testing
Why backups that have never been restored fail when needed, and how to find out: spot restores, full restores of a server to an isolated machine, controller program restores to a spare, archive reads, timing each one, and the findings and record that follow.
8 min readUpdated Sep 5, 2026
Offline Copies
The backup copy that survives ransomware: why anything reachable over the network will be encrypted too, what offline and immutable mean, options from rotated drives to immutable storage, what goes in the offline set, and the restore test that uses it.
8 min readUpdated Sep 5, 2026
Configuration Baselines
A known-good record of how every part of the control system is configured, captured at acceptance and kept current through change management: what to baseline, how to capture and store it, how to compare on a schedule, and what an unexplained difference means.
8 min readUpdated Sep 5, 2026
Change Management for OT
A change process sized for a utility control system: what counts as a change, the request with risk and rollback, owner approval, the window, backup before and verification after, the baseline update, the emergency path, and the record.
9 min readUpdated Sep 5, 2026
Isolating a Compromised System
Cutting a compromised machine, segment, or site off from the control system without stopping the process: who may decide, isolation points planned in advance, disconnecting the network rather than the power, running on manual control, and preserving evidence.
9 min readUpdated Sep 5, 2026
Recovery and Restoration
Bringing a control system back after a compromise without reintroducing it: controllers verified against baselines first, servers rebuilt from clean media and project exports, every credential changed, hardening, staged reconnection, and end-to-end tests.
9 min readUpdated Sep 5, 2026
Reporting Requirements
Who a water or wastewater utility must tell about a cyber incident, how fast, and what to say: the federal critical infrastructure reporting rule, state laws, the drinking water regulator, public notification, law enforcement, the sector center, and insurers.
9 min readUpdated Sep 5, 2026
Building an OT Asset Inventory
The list of everything in the control system with a network interface or a program, and how to build one that is right: what counts, the fields to record, the site walk, the switch tables and passive listening that find the rest, and keeping it current.
9 min readUpdated Sep 5, 2026
Advisories and Alerts
Where a utility learns its equipment has a known vulnerability and what to do with the news: the government and vendor advisory feeds, the sector center, the exploited catalog, subscribing by product, a weekly triage on exposure and consequence, and records.
8 min readUpdated Sep 5, 2026
Risk-Based Patching
Deciding what to patch first when everything cannot be patched at once: priority from exposure, exploitation, and consequence rather than scores, tiers with timelines, different rules for servers, network gear, and controllers, and the written accept decision.
8 min readUpdated Sep 5, 2026
Compensating Controls
What to do about a vulnerability that cannot be patched now or ever: restricting who can reach it, disabling the service, blocking dangerous protocol functions, allowlisting, monitoring, physical and procedural controls, matched to the attack path.
8 min readUpdated Sep 5, 2026
AWIA Requirements
What the 2018 water infrastructure act requires of community water systems: a risk and resilience assessment and an emergency response plan, certified on a schedule by size and repeated every five years, with cybersecurity named in both, and who is covered.
9 min readUpdated Sep 5, 2026
EPA Guidance
What the federal environmental agency provides to water and wastewater utilities on cybersecurity and what it expects: the free assessment, the checklist aligned with federal goals, joint incident response guidance, the enforcement position, and how to use it.
8 min readUpdated Sep 5, 2026
CISA Resources
What the federal cybersecurity agency provides to utilities without charge: the performance goals, regional advisors, external vulnerability scanning, control system advisories, the exploited catalog, a self-assessment tool, exercises, and incident reporting.
8 min readUpdated Sep 5, 2026
VLAN Segmentation
Using VLANs to build the zones of a control network on shared switches: what a VLAN separates and what it does not, the zone-to-VLAN mapping, trunks and the native VLAN, routing only through a firewall, and where separate hardware begins.
9 min readUpdated Sep 5, 2026
Data Diodes
Hardware that lets data flow one way only, from the control network outward, with no physical return path: what a data diode and a unidirectional gateway are, where they belong, what they can and cannot carry, and when a firewall is enough instead.
8 min readUpdated Sep 5, 2026
Segmenting a Remote Site
A lift station, a well, or a tank site as its own zone: the site firewall and what it permits, the modem as transport with no public address, cameras and extras off the control segment, engineering access through the plant, and local control without the link.
9 min readUpdated Sep 5, 2026
VPN Design
How a VPN fits remote access for a control system: it terminates in the DMZ and lands on a jump host, never the control network; site-to-site tunnels carry telemetry; user tunnels require multi-factor and individual accounts; the concentrator is patched fast.
9 min readUpdated Sep 5, 2026
Multi-Factor Authentication
Requiring a second proof of identity beyond a password, where it matters most in a control system and how to do it without locking an operator out: the factor types, where it is mandatory, where it does not fit, enrollment and recovery, and vendor accounts.
8 min readUpdated Sep 5, 2026
Session Logging
Recording every remote session into the control system: who connected, from where, when, to what, and what they did, from the VPN log through jump host session recording to the SCADA audit trail and controller change log, stored off the systems and reviewed.
8 min readUpdated Sep 5, 2026
Deep Packet Inspection
What a firewall can do when it understands the control protocols: allowing reads and blocking writes, permitting programming only from one workstation in a window, rejecting malformed messages, and alerting on function codes that should never appear.
8 min readUpdated Sep 5, 2026
Firewall Logging and Review
Making the firewall log useful: logging on every rule including sensitive permits, sending logs to a collector off the firewall, what denials and unexpected permits mean, a weekly review a small utility can sustain, and the alerts worth waking someone for.
8 min readUpdated Sep 5, 2026
Disabling Unused Services
Every service a device runs is a way in, and most ship with more running than the plant uses: web servers, file transfer, shells, discovery, management protocols, unused ports. Finding what is listening, deciding what the plant needs, and turning off the rest.
8 min readUpdated Sep 5, 2026
How to Assign IP Addresses on a Control Network
Build an addressing plan before the first device is configured: one subnet per zone and site, a fixed block layout so an address says what the device is, static addresses on everything that controls a process, and a schedule that is kept current.
9 min readUpdated Sep 5, 2026
How to Configure VLANs on a Control Network
Turn a zone plan into switch configuration: a VLAN per zone with its own subnet, access ports for devices, tagged trunks between switches, a native VLAN that carries nothing, a separate management VLAN, and routing between VLANs only through the firewall.
10 min readUpdated Sep 5, 2026
How to Build a Sequencer
Build a step sequencer in a controller that will not stick, restart into the wrong step, or leave equipment half way: define the steps from the narrative, choose a step register, and test every path before the plant depends on it.
9 min readUpdated Sep 5, 2026
How to Trend Data
Build trends that operators use: choose the tags that tell one story per trend, set scales and time spans that show the behavior, and make ad hoc trending fast enough that an operator reaches for it before a phone call.
7 min readUpdated Sep 5, 2026
How to Configure a Historian
Set up a process historian that collects what matters and keeps it: decide the tags and their classes, set collection intervals and deadbands per class, size the storage and the retention, and hand the operators a working trend on day one.
8 min readUpdated Sep 5, 2026
How to Build Pump Graphics
Build a pump symbol and faceplate that operators can read at a glance and use without error: a symbol that shows state by shape and a muted palette with color reserved for abnormal, and a test against the high-performance HMI principles before it is deployed.
8 min readUpdated Sep 5, 2026
How to Configure Remote Access
Give operators and engineers a way into the SCADA system from outside that does not give it to anyone else: a virtual private network with multi-factor authentication terminating in a demilitarized zone, and a test that proves the path works and that the.
8 min readUpdated Sep 5, 2026
How to Size an Enclosure
Size a control panel enclosure so that everything fits, cools, and can be worked on: lay out the components with their clearances and wireway, add the spare space the plant will need, and mounting before ordering.
8 min readUpdated Sep 5, 2026
How to Build Terminal Schedules
Produce the terminal schedule that lets a technician find any wire: define the strips and their numbering, list every terminal with its wire numbers, the device and the field destination, and keep it current through every change.
7 min readUpdated Sep 5, 2026
Cable Routing Problems
Noise that comes from where a cable runs: signal cables sharing a conduit, tray, or wireway with power or drive cables, long parallel runs, and shallow crossings. How coupling works, the separations that prevent it, and how to find the shared path.
9 min readUpdated Sep 5, 2026
Unshielded Cable in a Noisy Run
The signal was run in plain conductors through a route full of power and drive cables, and now it is noisy. What unshielded cable cannot do, how to prove the cable is the problem before pulling a new one, and the options when replacing it is not possible.
9 min readUpdated Sep 5, 2026
Panel Overheating
A panel that runs hot: drives tripping on temperature in the afternoon, controllers faulting in summer, components discolored, a fan that never stops. The causes from an undersized enclosure to a clogged filter, measuring the rise, and the fixes.
8 min readUpdated Sep 5, 2026
Poor Signal Margin
A path with too little signal above receiver threshold to survive rain, leaves, and inversions: the link budget from transmitter to receiver, the Fresnel zone, and why the margin is smaller than the study said. How to compute, measure, and add to it.
9 min readUpdated Sep 5, 2026
Interference on Channel
Data lost on a strong-signal path: another system on the frequency, a nearby transmitter overloading the receiver, intermodulation on a shared tower, drive noise, or a stuck transmitter. How to measure the noise floor, find the source, and cure it.
8 min readUpdated Sep 5, 2026
Weak Cellular Signal
A modem at the edge of coverage: the signal readings that matter, an antenna inside a metal enclosure or vault, the wrong band, a damaged antenna or lossy coax, a tower or carrier change, and fixes from a mast antenna to a directional one or a new medium.
8 min readUpdated Sep 5, 2026
High Optical Loss
A link that is up but running near the receiver floor: the loss budget from transmitter to receiver and what ate it. Dirty connectors, bad splices, tight bends, a run too long for the module, or a wrong fiber type. Measuring the loss and getting margin back.
9 min readUpdated Sep 5, 2026
Wrong Fiber Type or Wavelength
A link that will not come up, or runs with high loss, because parts do not match: single-mode modules on multimode fiber, a multimode cord in a single-mode run, mixed grades, different wavelengths, or a same-wavelength bidirectional pair. Reading the markings.
8 min readUpdated Sep 5, 2026
Broadcast Storm
A network suddenly slow or dead everywhere, every link light solid: a loop between switches without protection, a failed ring protocol, or a device flooding broadcasts. Recognising a storm, breaking it with a cable pull, finding the loop, and preventing it.
8 min readUpdated Sep 5, 2026
Duplicate or Missing History
A historian with two records for one moment, or none: a redundant pair both collecting, a buffer that forwarded twice, a tag under two names, a daylight saving shift, or a source that resends on reconnect. Cleaning the record without inventing data.
8 min readUpdated Sep 5, 2026
How to Read a P&ID
What a piping and instrumentation diagram shows, how ISA-5.1 tag bubbles and line types encode the control system, and how to trace a loop across sheets.
8 min readUpdated Sep 5, 2026
Control Narratives
What a control narrative is, what it must contain, how to write statements that can be tested, and how it drives programming, FAT, and the owner’s acceptance.
9 min readUpdated Sep 5, 2026
Sequences of Operation
Writing the ordered, step-by-step description of what a system does: states, transitions, timeouts, and the format that lets a programmer implement it and a tester verify it without interpretation.
8 min readUpdated Sep 5, 2026
Cause and Effect Matrices
The table that lists every trip condition against every action it causes: how to build one, what goes in the cells, how it distinguishes hardwired from software protection, and how it becomes the test.
7 min readUpdated Sep 5, 2026
Factory Acceptance Testing
Testing a control system before it leaves the shop: what must exist before the test, how the procedure is built from the narrative and the matrix, how the field is simulated, what is witnessed, and what the punch list and the sign-off mean.
9 min readUpdated Sep 5, 2026
Site Acceptance Testing
Proving the installed system with the real field: loop checks first, then end-to-end I/O, real communications, sequences on real equipment, alarms to real recipients, and failure modes on the real network, with the record that becomes the as-built.
8 min readUpdated Sep 5, 2026
I/O Lists
The document that ties the field to the controller: what every I/O list column means, how tags, terminals, and module channels are assigned, spare capacity rules, how the list drives the drawings and the program, and how to keep it true after commissioning.
9 min readUpdated Sep 5, 2026
Instrument Lists
The index of every measuring and final control device on a project: what the instrument list records, how it grows from the P&ID into specification sheets and calibration records, the columns that matter at each stage, and how it becomes the asset register the utility maintains.
8 min readUpdated Sep 5, 2026
Control Schematics
The ladder-style drawing of every control circuit in a panel: how a schematic is organized by line number, the conventions for contacts, coils, and cross-references, what belongs on a schematic and what belongs on a wiring diagram, and reading one under pressure.
9 min readUpdated Sep 5, 2026
Commissioning Checklist
From energization to handover: the sequence of commissioning activities for a control system, the prerequisites and records for each, who signs what, and the checklist that keeps a project from being declared finished while half of it has never been tested.
10 min readUpdated Sep 5, 2026
ISA Standards for Controls
The International Society of Automation standards a controls practitioner meets: ISA-5.1 symbols and tags, ISA-18.2 alarm management, ISA-101 HMI design, ISA-88 and ISA-95 for batch and enterprise integration, ISA-99 which became IEC 62443, ISA-20 specification forms, and how each is used on a water or wastewater project.
8 min readUpdated Sep 5, 2026
IEC Standards for Controls
The International Electrotechnical Commission standards a controls practitioner meets: IEC 61131 for programmable controllers and their languages, IEC 62443 for security, IEC 61511 for safety instrumented systems, IEC 60529 ingress protection ratings, the telemetry protocols, and how IEC and North American standards fit together.
8 min readUpdated Sep 5, 2026
NFPA Standards for Controls
The National Fire Protection Association documents that reach into a control system: NFPA 70, the National Electrical Code, and the articles that govern panels, motors, and instrumentation; NFPA 70E for electrical safety at work; NFPA 79 for industrial machinery; NFPA 820 for wastewater plant hazardous area classification; and NFPA 110 where standby power meets the controls.
9 min readUpdated Sep 5, 2026
UL Standards for Controls
The UL listings behind the components and the panels: UL 508A for industrial control panels and its SCCR supplement, UL 508 and UL 60947 for the components in them, UL 489 and UL 1077 for breakers and supplementary protectors, UL 248 fuse classes, UL 50 and 50E for enclosures, UL 698A for hazardous-location panels, and what a listing, a recognition, and a mark actually mean.
9 min readUpdated Sep 5, 2026
Wiring Diagrams
The drawing that says where every wire goes: panel wiring and interconnection diagrams, and the conventions of wire numbers, conductor colors, terminal numbers, and cable numbers that make them readable. What belongs here versus on the schematic.
9 min readUpdated Sep 5, 2026
Network Drawings
The two drawings every control network needs: a logical drawing of zones, subnets, VLANs, firewalls, and conduits, and a physical drawing of switches, ports, cables, fiber, radios, and sites. What each shows and why they are sensitive.
9 min readUpdated Sep 5, 2026
Panel Layouts
The drawing of what goes where inside a control panel: enclosure, back plate with every component to scale and keyed to the bill of material, wireways, terminals, door devices, and entries. The conventions, the required spacings, and the checks.
9 min readUpdated Sep 5, 2026
Cable Schedules
The list of every cable with what it is, where it runs, and where it lands: the columns, the numbering convention, types and signal classes, routes through conduits and trays, lengths, terminations, spares, and status from design through as-built.
8 min readUpdated Sep 5, 2026
Fiber Schedules
The record of every fiber strand between every pair of patch panels: cable identifiers, strand numbers and the standard color sequence, fiber type, connectors, what each strand carries, splices, lengths, and test results, with the labeling that matches it.
8 min readUpdated Sep 5, 2026
Network Schedules
The tables behind the network drawings: the address schedule of every device, the switch port schedule of every port, the VLAN table, and the conduit list of what the firewalls permit. How they are built, kept as the single source of truth, and protected.
8 min readUpdated Sep 5, 2026
Functional Descriptions
The system-level document that states what a control system does, organized from the overview down to each piece of equipment in one format: modes, control, setpoints, permissives, interlocks, alarms, sequences, and failure behavior, and how it is used.
10 min readUpdated Sep 5, 2026
Design Checklist
A review checklist for a control system design at each stage from concept to issued for construction: documents, architecture, controllers and I/O, panels and power, instruments, networks and security, SCADA and alarms, deliverables, and commissioning.
11 min readUpdated Sep 5, 2026
Calibration Checklist
The checklist for one calibration event, from work order to the sticker on the instrument: notify operations, loop in manual, alarms inhibited, the reference standard, as-found, adjustment, as-left, the loop check, restoration, and the record.
8 min readUpdated Sep 5, 2026
NIST Publications for Control Systems
The National Institute of Standards and Technology documents a control engineer will meet: the Cybersecurity Framework, the operational technology security guide, the control catalog, the digital identity guideline, and the incident handling guide.
9 min readUpdated Sep 5, 2026
CISA Guidance as a Reference
How the federal cybersecurity agency publications serve as reference standards for a utility: the performance goals as a baseline for policy and procurement, the water sector goals, secure-by-design principles for vendors, and the advisories.
8 min readUpdated Sep 5, 2026
EPA Rules and Their Control System Implications
The federal environmental agency rules that shape what a water or wastewater control system must measure, record, and report: the surface water rules, residual and byproduct rules, groundwater and lead rules, discharge permits, and record retention.
10 min readUpdated Sep 5, 2026
AWWA Standards and Manuals
What the American Water Works Association publishes that a control engineer uses: the instrumentation and control manual, the risk and resilience standard behind the act assessments, the security and emergency standards, and the cybersecurity tool.
8 min readUpdated Sep 5, 2026
Where the Logic Should Live: Controller, SCADA, or Relay
Every control decision has a home, and putting it in the wrong one is the root of most plants that are hard to operate. A rule for deciding what belongs in the controller, what belongs in SCADA, and what belongs in a relay.
9 min readUpdated Sep 5, 2026
What a Small Utility Should Ask Before Buying SCADA
A utility with a plant, a few dozen remote sites, and two operators on call is buying a system it will live with for twenty years. The questions that decide whether it works out, and they are not about features: licensing, staffing, and the exit.
9 min readUpdated Sep 5, 2026
The Lift Station That Overflowed With Everything Working
A composite of overflows that happen at well-built stations: every pump ran, every alarm fired, every device did what it was designed to do, and the handful of changes that break the chain.
9 min readUpdated Sep 5, 2026
Calibration Is a Program, Not an Event
An instrument calibrated once at startup and again when someone complains is an instrument whose readings cannot be trusted in between. What a calibration program is, and how a small utility runs one without a full-time instrument technician.
8 min readUpdated Sep 5, 2026
The Panel You Can Troubleshoot at Two in the Morning
Panels are designed for the day they are built and used for the nights they fail. The design choices that decide whether a technician with a flashlight and a meter can find the fault: labels and wire numbers, and the fuse that tells you it blew.
8 min readUpdated Sep 5, 2026
Fiber Between Buildings, Every Time
The copper Ethernet cable between two buildings works on the day it is pulled and costs the plant a controller, a switch, and how to specify it so it stays simple.
7 min readUpdated Sep 5, 2026
The Cellular Router Is the Front Door
The most common way into a small utility control system is not a sophisticated attack on the plant firewall. It is a cellular router at a lift station with a public address and the password it shipped with. How these get installed, and the short list of.
8 min readUpdated Sep 5, 2026
Measure Before You Replace
Parts-swapping is the most expensive way to troubleshoot and the most common. A method for controls faults that starts with a measurement, splits the problem in half at every step, and ends with a cause instead of a coincidence.
8 min readUpdated Sep 5, 2026
The Control Narrative Is the Contract
Most control system disputes, delays, and disappointments trace to one missing document: a narrative that says, in plain language, and how it keeps paying after startup.
8 min readUpdated Sep 5, 2026
The Knowledge That Leaves With the Retiring Technician
Water and wastewater utilities are losing the people who know how their control systems actually work, and a practical program for capturing it while there is still someone to ask.
8 min readUpdated Sep 5, 2026
What Integrator Consolidation Means for a Small Utility
The regional controls integrator that built a utility system over twenty years is being bought, merged, or closed, and how to stop depending on any single firm for the system it owns.
7 min readUpdated Sep 5, 2026
Alarms Nobody Answers
A SCADA system that raises eight hundred alarms a day has trained its operators to ignore it. How a small plant gets there, what the standing alarm list is telling you, and a one-day rationalization that gives the alarm system its voice back.
9 min readUpdated Sep 5, 2026
Heat Kills Panels Slowly
Nothing in a control panel fails the day it gets hot. Power supplies, drives, relays, and the controller lose life a summer at a time, and what to do about it that actually works outdoors.
9 min readUpdated Sep 5, 2026
One Flat Network Is One Big Fault Domain
A looped patch cable in an office closet took down every PLC at the plant, because the office and the plant were one network. Why a flat network makes every fault a plant-wide fault, and how to get there one switch at a time.
9 min readUpdated Sep 5, 2026
As-Built Means Someone Walked the Panel
The drawings in the panel pocket are the ones from the bid set, and how a small utility keeps its drawings true after the integrator has gone.
9 min readUpdated Sep 5, 2026
UL 508A Industrial Control Panels
What the listing actually covers, what has to appear on the label, and the requirements that most often cause a panel to fail inspection.
9 min readUpdated Aug 25, 2026
ISA-18.2 Alarm Management
The lifecycle standard for alarm systems, the rate targets that define a workable system, and why alarm rationalization is the step nobody wants to fund.
10 min readUpdated Aug 15, 2026
How to Size a Control Panel Power Supply
Add up the real load, account for inrush and simultaneity, add headroom, and check the heat you just added to the enclosure.
7 min readUpdated Aug 14, 2026
High Performance HMI Design
Grey backgrounds, reserved color, and displays designed to make abnormal conditions obvious rather than to look impressive in a demo.
8 min readUpdated Jul 24, 2026
Interlocks and Permissives
A permissive lets you start. An interlock stops you. Confusing the two produces equipment that either will not run or will not protect itself.
7 min readUpdated Jun 27, 2026
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Content on CurryControls.com is general technical reference information provided for educational and reference purposes only. It is not engineering advice for a specific installation. All information must be independently verified against current codes, standards, manufacturer documentation, project requirements, and qualified professional judgment before it is relied upon or applied.