Glossary

Control panel terms, explained

74 terms that turn up on quotations, drawings, specifications and site, each in a paragraph. Where we have written more, the link takes you there.

Adoptable pumping station: A sewage pumping station built to be handed over to the water company, which then owns and maintains it, under a Section 104 agreement. Built to the Design and Construction Guidance plus the water company's own amendments, which dictate the kiosk, telemetry, alarms and documentation. Adoptable control panels →
Ammeter: A meter on the panel door showing the current a pump motor is drawing. A rising reading over months is the earliest sign of a pump that is blocking or wearing.
Analogue signal (4-20mA, 0-10V): A signal whose value varies continuously to represent a measurement or a command: 4-20mA for a level or pressure sensor, 0-10V for a valve or fan speed. Contrast with a digital signal, which is simply on or off. Analogue vs digital signals →
Anti-condensation heater: A small heater on a thermostat inside an outdoor enclosure or kiosk, keeping the air a few degrees above the outside so moisture never condenses on the switchgear. Not optional outdoors.
Assist float: The third float in a duty/assist pump station. When it rises, the second pump starts alongside the first because the inflow is more than one pump can handle. Where to hang the floats →
ATEX: The EU directives, and their UK equivalent, for equipment used in potentially explosive atmospheres. A sewage wet well can be a hazardous zone, so the floats or sensors in it must be connected through intrinsically safe barriers in the panel. Why sewage pits need ATEX rated equipment →
BMS (building management system): The control system that runs a building's heating, ventilation, cooling and services from outstation panels around the building, reporting to a head end. G&G builds the outstation and motor control panels the BMS lives in. BMS control panels →
Booster set: Two or more pumps with a pressure vessel and a control panel, holding a set pressure in a water supply as demand varies. Usually inverter-driven, from a pressure transducer. Booster control panels →
BS 7671: The IET Wiring Regulations: the UK standard for electrical installations. The installation that feeds and leaves a panel is inspected and tested to it. The panel itself is built to BS EN 61439-2.
BS EN 60204-1: The standard for the electrical equipment of machines. Applies alongside BS EN 61439-2 to any panel that controls a motor-driven machine, which includes pump panels. Standards and compliance →
BS EN 61439-2: The standard for low-voltage switchgear and controlgear assemblies, the part covering power switchgear and control panels. Requires design verification of the design and routine verification of every panel built. BS EN 61439-2 for panel buyers →
Capacitor (start and run): Single-phase motors cannot start on their own; a start capacitor gives the push and a run capacitor keeps the motor efficient. A capacitor-start panel switches them at the right moment. Three-phase motors need neither. Why single-phase motors need capacitors →
CE marking and UKCA marking: Conformity marks declaring that a product meets the applicable safety and EMC regulations. CE is the EU mark and continues to be recognised in Great Britain; UKCA is the UK mark. Either is the manufacturer's own declaration, backed by a Declaration of Conformity. UKCA and CE marking on control panels →
Contactor: The electrically operated switch that connects a motor to the supply. One per pump, controlled by the panel's logic, sized for the motor current and the number of starts.
Control circuit: The low-power wiring inside the panel that makes the decisions: floats, relays, timers, switches and lamps, typically at 230V or 24V. Separate from the power circuit that actually feeds the motors.
Creepage and clearance: The minimum distances between live parts, across a surface (creepage) and through the air (clearance), that a panel must maintain so a fault cannot arc. Checked in routine verification.
Declaration of Conformity: The manufacturer's legal statement that a product complies with the regulations that apply to it, listing the standards used. The document behind a CE or UKCA mark.
Design and Construction Guidance (DCG): The national standard for adoptable sewers and pumping stations in England and Wales, which replaced Sewers for Adoption in 2020. Each water company adds its own amendments.
DI, DO, AI, AO: The four kinds of BMS point: digital input (reads on/off), digital output (switches on/off), analogue input (reads a value), analogue output (commands a value). A points list is a count of each. How to write a BMS points list →
DIN rail: The standard 35mm metal rail that components clip onto inside a panel: terminals, relays, controllers, power supplies. Makes components quick to fit and replace.
Direct-on-line (DOL): The simplest way to start a motor: connect it straight to the supply through a contactor. Right for most pump motors up to about 18A. Larger motors use star/delta, a soft starter or an inverter to limit the starting current. Understanding motor starting methods →
Duty changeover: Alternating which pump is duty on each cycle, so both pumps wear evenly and both get exercised. Standard on G&G twin pump panels.
Duty/assist: A twin pump arrangement where one pump runs normally and the second joins in when the level keeps rising. Combined with duty changeover, it is what most twin pump wastewater stations run. Duty/standby, duty/assist and duty changeover explained →
Duty/standby: A twin pump arrangement where the second pump only runs if the first fails. Used where the two must never run together.
Earth bar: The bar inside a panel where every earth conductor terminates, one conductor per terminal. Multiple earths on one stud are not permitted. Why multiple earths on the same stud are banned →
EMC (electromagnetic compatibility): A product's ability neither to emit electrical interference beyond set limits nor to be upset by it. Covered by the EMC Regulations; inverters in particular need filtering to comply.
Enclosure: The box the panel is built into: powder-coated mild steel as standard, polyester (GRP) for outdoors, stainless steel for aggressive environments, rated by IP for dust and water. Kiosk or wall-mounted? →
Float switch: A float on a cable containing a tilt switch: it hangs in the wet well and makes or breaks a contact as the level passes it. Four floats, stop, start, assist and high level, control a typical twin pump station. Floats, radar or hydrostatic? →
Form of separation: How the inside of a panel is divided to protect someone working on one part from live parts elsewhere, from Form 1 (no separation) to Form 4b (every unit and its terminals separated). Defined in BS EN 61439-2. Form 4 or Form 2 enclosures →
Free issue: Components, usually BMS controllers, bought by the customer and sent to the panel builder to be fitted, rather than supplied with the panel. Free-issue controllers →
Full load current (FLC): The current a motor draws at its rated load, printed on the nameplate. The number the overload is set to and the switchgear is sized from. What's the full load current of the motor? →
Generator inlet: A socket on the panel or kiosk, typically 32A, 63A or 125A, with a changeover arrangement, so a portable generator can run the station during a power cut.
GRP kiosk: A free-standing glass-reinforced plastic housing on a plinth, with a lockable door, that a pump control panel is built into at a free-standing pump station. Usually with a light and a heater; required for adoptable stations.
Hand/off/auto: The three-position switch for each pump on the panel door. Hand runs the pump regardless of the floats, off stops it, auto lets the panel control it. Leave both pumps in auto for changeover to work.
High level alarm: The alarm raised when the level in a wet well rises above the point the pumps should have handled: a beacon, a sounder, and on a Telemetrix panel a text and email. The warning before an overflow. The high level alarm has gone off: what to do →
HMI (human-machine interface): A touchscreen on the panel door showing level, status and alarms and letting set points be entered on screen rather than by moving floats. Fitted to Basix View and Telemetrix View. Telemetrix View →
Hours run meter: A counter on the door totalling how long each pump has run. Used to schedule servicing and to check the two pumps in a station are sharing the work.
Hydrostatic level sensor: A sealed pressure sensor lowered to the floor of the wet well on its cable. It measures the pressure of the liquid above it and gives a continuous 4-20mA level signal. Accurate in narrow, shallow and deep pits alike, with no moving parts; usually our recommendation. Floats, radar or hydrostatic? →
IK rating: An enclosure's impact resistance to BS EN 62262, from IK00 to IK10 (20 joules). Matters for panels in public places; GRP kiosks are typically IK10.
Insulation resistance: The resistance between live conductors and earth, measured at 500V DC. A routine test on every panel; a low reading means damaged insulation or a wiring error. What a test certificate should include →
Interposing relay: A relay between a controller output and the plant it switches, so the small controller output never carries the load and the plant can never feed back into the controller.
Intrinsically safe (IS) barrier: A device in the panel that limits the energy on a circuit entering a hazardous zone so it cannot ignite gas. Required for floats and sensors in an ATEX-rated wet well.
Inverter (variable speed drive, VSD, VFD): A drive that varies the frequency of the supply to a motor and so its speed. Used where flow or pressure must vary, as in booster sets, and to soften starting on larger pumps. Inverters no longer break the bank →
IP rating: Two digits, to BS EN 60529, for how well an enclosure keeps out solids and water: IP55 is the standard for control panels, IP66 for a panel that faces the weather. The rating holds only while glands and door are right. IP ratings explained →
Isolator (door-interlocked): The main switch that disconnects the panel from the supply. Door-interlocked means the door cannot be opened while it is on, and a shaft guide stops it being defeated. What isolators actually do →
Kiosk: See GRP kiosk.
Level sensing: How a pump panel knows where the liquid is: float switches, a hydrostatic sensor, a radar or ultrasonic head, or conductivity probes. The single biggest choice in specifying a pump panel. Floats, radar or hydrostatic? →
MCC (motor control centre): A panel, usually floor-standing, containing the starters for several motors in one place, typically the plant room of a building.
Outstation: A BMS panel around the building housing a controller and its I/O, connected to the plant it controls and to the head end over the network. What's inside a BMS outstation panel →
Overload relay: The device that trips a motor if it draws more than its full load current for too long, protecting it from a blockage or a fault. Set to the nameplate FLC; a trip lamp shows when it has operated. What you are doing wrong with overloads →
P number: The identifier on the label inside a Telemetrix panel door that registers the panel to a pump station in the Dashboard and identifies it to our technical team. Telemetrix setup guide →
Panel builder: A manufacturer that designs and assembles control panels from switchgear, controls and an enclosure, and is the manufacturer of the finished assembly for the purposes of the regulations. G&G is one.
PLC (programmable logic controller): An industrial computer that runs the control logic of a panel where relay logic is not enough. Adds programming cost on the first panel; repeat panels do not pay it again.
Points list: The schedule of every input and output a BMS panel handles. The document a BMS panel is priced and drawn from. How to write a BMS points list →
Pressure transducer: A sensor giving a 4-20mA signal proportional to pressure. What a booster set panel controls from.
Radar level sensor: A non-contact head mounted above the liquid that times an echo off the surface to give a continuous level. Nothing in the liquid to foul, but it needs a clear view down, so it does not suit narrow pits.
RCD (residual current device): A device that trips when current leaks to earth. A wet pump cable or a failing motor seal will trip an RCD long before it trips an overload.
Rising main: The pipe that carries pumped wastewater up and away from a pumping station to the gravity sewer. Its friction losses are why two pumps together do not move twice the flow of one.
Routine verification: The set of checks and tests BS EN 61439-2 requires on every individual panel before it leaves the factory, recorded on the test certificate. What a test certificate should include →
Seal leak detection: A probe in a submersible pump's oil chamber that signals when water has got past the outer seal. The panel option fits a relay and lamp per pump so the warning is seen before the motor fails.
Section 104 (S104) agreement: The agreement under the Water Industry Act by which a developer builds sewers and pumping stations to the water company's standard and the company adopts them on completion.
Single phase: A 230V supply with one live conductor and a neutral. Single-phase pump motors need capacitors to start; the panel is built accordingly.
Soft starter: A solid-state device that ramps a motor up to speed to limit the starting current, without the speed control of an inverter. Used between DOL and inverter in cost and capability.
Star/delta starting: A way of starting a larger three-phase motor at reduced voltage (star) and then switching to full voltage (delta), cutting the starting current to about a third. Needs a six-core cable to the motor. Star/delta motor starting: why is it so misunderstood? →
Stepping relay: The relay in a twin pump panel that swaps which pump is duty on each cycle, so both wear evenly. Also called an alternating, switching or flip-flop relay. The older mechanical type is the most common component to fail on an old pump panel: the trigger input sits across the coil and eventually cooks it. G&G panels use a universal stepping relay, which takes its supply and its trigger on separate terminals, and it carries a lifetime warranty. Why stepping relays fail →
Surge protection device (SPD): A device that clamps voltage spikes, from lightning or switching, before they reach the electronics. Type 2 at the panel supply, type 3 close to sensitive equipment; a BMS controller on long cables should have both. Do you need surge protection in your panel? →
SWA (steel wire armoured) cable: The armoured cable used between a panel and a pump station or outdoor equipment. Glanded so the armour is earthed. Should you gland both ends of SWA cable? →
Telemetry: Sending a panel's status and alarms to people elsewhere: originally over a phone line to a control room, now over 4G, WiFi or Ethernet to a phone. Telemetrix panels have it built in: email alerts are free, texts 10p each, and the optional Dashboard is from £6 a month. Telemetrix →
Test certificate: The record of the routine verification of an individual panel: identification, checks, insulation resistance, functional test and the tester's signature. Ships inside the door of every G&G panel. What a test certificate should include →
Three phase: A 400V supply with three live conductors, with or without a neutral. Three-phase motors are simpler, more efficient and block less often than single-phase ones. Why single-phase pumps block more often →
Transformer: Used in a panel to make the control voltage from the supply: 230V from a 400V supply with no neutral, or 24V AC for BMS field devices. Transformers: a quick guide →
Ultrasonic level sensor: A non-contact head that measures level by the echo of a sound pulse. Similar in application to radar, and similarly needs a clear view down the chamber.
Volt-free contact: A relay contact in the panel that carries no voltage of its own, so someone else's telemetry or BMS can wire through it to read run, fault or high level status.
Wet well: The chamber at a pumping station that collects wastewater and houses the submersible pumps and the level controls.

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