Glossary
The terms used in our guides, explained in one or two sentences: power, generators, electrical work, pumps and site equipment. Each term links to the guide that covers it.
57 terms
- Continuous power (COP)
- An ISO 8528-1 rating for a constant load with no limit on hours. "Continuous power" means COP, not prime power.
- Read the guide: Prime (PRP) vs standby (ESP) power: which rating matters?
- Direct-on-line start (DOL)
- A motor switched straight onto the supply. Our finder's method counts three times the motor's power at start-up.
- Read the guide: Generator sizing for a shop, clinic or workshop: 3 worked examples
- ISO 8528-1
- The international standard that defines generator power ratings, including prime power (PRP) and standby power (ESP).
- Read the guide: Prime (PRP) vs standby (ESP) power: which rating matters?
- kVA (kilovolt-ampere)
- The unit of apparent power: the voltage multiplied by the current the alternator must supply. Generator ratings are given in kVA.
- Read the guide: kVA vs kW: what is the difference for a generator?
- kW (kilowatt)
- The unit of active power, the power that turns a motor, lights a lamp or heats. For a generator, kW = kVA × 0.8.
- Read the guide: kVA vs kW: what is the difference for a generator?
- Load-shedding
- An organised power cut: when the electricity available is not enough, the utility shares it between districts in turn.
- Read the guide: Power cuts in Kinshasa: how to keep the lights on at home or at work
- Low-load clogging (wet stacking)
- A diesel that runs for long periods at very low load, below about 30%, burns its fuel poorly: fuel and oil collect in the exhaust and the engine clogs up.
- Read the guide: Oversized generator: why a diesel clogs up at low load
- Power factor (cos φ)
- The ratio of active to apparent power (kW ÷ kVA), between 0 and 1. Generator datasheets set it at 0.8.
- Read the guide: kVA vs kW: what is the difference for a generator?
- Power reserve
- A margin added to the calculated load so the set does not run at its limit. Our guides use 25%.
- Read the guide: What size generator for a house in Kinshasa?
- Prime power (PRP)
- Under ISO 8528-1, the power a set can supply for an unlimited number of hours a year under variable load. It is the rating to use for daily running.
- Read the guide: Prime (PRP) vs standby (ESP) power: which rating matters?
- Runtime
- How long a set runs on one tank: the tank capacity divided by the hourly fuel consumption, at a given load.
- Read the guide: Diesel generator fuel consumption: litres per hour from 13 to 2,000 kVA
- Simultaneous-use factor
- The share of appliances that run at the same time. Our finder applies one per type of use (shop, clinic, workshop…).
- Read the guide: Generator sizing for a shop, clinic or workshop: 3 worked examples
- Standby power (ESP)
- Under ISO 8528-1, a rating meant for 200 running hours a year at most. It is higher than prime power but does not suit a set that runs every day.
- Read the guide: Prime (PRP) vs standby (ESP) power: which rating matters?
- Star-delta start
- A two-step start that lowers the current drawn by a three-phase motor. Our finder's method counts twice the motor's power.
- Read the guide: Generator sizing for a shop, clinic or workshop: 3 worked examples
- Starting current
- The current an electric motor (pump, air conditioner, compressor) draws when it starts, far higher than when running. It often sets the generator size.
- Read the guide: Generator sizing for a shop, clinic or workshop: 3 worked examples
- Variable frequency drive (VFD)
- A device that starts a motor gradually and controls its speed. The starting current becomes small, which reduces the generator size needed.
- Read the guide: Generator sizing for a shop, clinic or workshop: 3 worked examples
- Air-cooled generator
- A set whose engine is cooled by a fan. Simple and compact, it is built for intermittent use.
- Read the guide: Air-cooled or water-cooled generator: which one?
- Alternator
- The machine driven by the engine that produces the current. Its datasheet gives the make, model, voltage and frequency.
- Read the guide: How to read a generator datasheet: engine, alternator, controller and tank
- AMF (automatic mains failure)
- A controller function that detects a mains failure and starts the set without anyone stepping in.
- Read the guide: Writing a generator specification for a tender in the DRC
- Automatic transfer switch (ATS)
- A device that switches the installation to the generator when the power goes and back to the grid when it returns. It prevents any back-feed into the grid.
- Read the guide: Installing a generator safely: location, ventilation, connection
- Controller (control module)
- The module that starts and stops the set, shows voltage, frequency, current and running hours, and shuts it down on a fault.
- Read the guide: How to read a generator datasheet: engine, alternator, controller and tank
- Copper or aluminium winding
- The metal of the alternator windings. Small petrol sets come with one or the other; the datasheet says which.
- Read the guide: Petrol generators from 2 to 7 kW: copper or aluminium winding, recoil or electric start?
- Datasheet
- The manufacturer's document that gives a model's figures. For a generator: engine, alternator, controller, enclosure and tank.
- Read the guide: How to read a generator datasheet: engine, alternator, controller and tank
- Inverter generator
- A set that converts its alternator's output electronically to give a stable voltage and frequency, suited to electronics.
- Read the guide: Diesel, petrol or inverter generator: which to choose?
- kWm
- The engine's mechanical power, in kilowatts. It is higher than the set's electrical output, because the alternator has losses.
- Read the guide: How to read a generator datasheet: engine, alternator, controller and tank
- Open-frame generator
- A set without an enclosure, more compact and lighter. It must stand under a shelter or in a ventilated room.
- Read the guide: Soundproof or open-frame generator: size, weight and noise
- Recoil and electric start
- Two ways to start a small set: by pulling a cord (recoil start) or with a battery and a button or key (electric start).
- Read the guide: Petrol generators from 2 to 7 kW: copper or aluminium winding, recoil or electric start?
- Soundproof generator
- A set inside an enclosure that reduces noise and protects it from the weather. For the same power it is larger and heavier than an open-frame set.
- Read the guide: Soundproof or open-frame generator: size, weight and noise
- Turbocharged engine
- An engine whose intake air is compressed by a turbocharger. In a Perkins engine code the letter T shows it; without a T the engine is naturally aspirated.
- Read the guide: Which Perkins engine powers which generator? Table from 13 to 2,000 kVA
- Water-cooled generator
- A set whose engine is cooled by a liquid that flows to a radiator. It runs for long hours under heavy load.
- Read the guide: Air-cooled or water-cooled generator: which one?
- Back-feed
- Generator current flowing back into the grid when the installation is not cut off from it. It can electrocute line workers; a transfer switch prevents it.
- Read the guide: Installing a generator safely: location, ventilation, connection
- Cable gland
- A fitting that grips a cable where it enters an enclosure. The right size keeps the enclosure sealed.
- Read the guide: IP ratings (IP44, IP55, IP65): choosing a junction box or enclosure
- Earthing
- The connection of metal parts to earth, which protects people if a fault occurs. A generator must be earthed.
- Read the guide: Installing a generator safely: location, ventilation, connection
- Flexible conduit
- Conduit that bends by hand, laid inside walls and partitions. To embed it in a concrete slab, use a model made for that purpose.
- Read the guide: What conduit size for how many wires? Rigid, flexible and HDPE conduit
- Frequency (50 Hz)
- The number of current cycles per second. The DRC grid runs at 50 Hz, in Kinshasa as in the provinces.
- Read the guide: Writing a generator specification for a tender in the DRC
- HDPE conduit
- High-density polyethylene conduit, common for long runs and outdoor links, including buried ones.
- Read the guide: What conduit size for how many wires? Rigid, flexible and HDPE conduit
- IP rating
- The IEC 60529 code: the first digit rates protection against solids and dust, the second against water. The higher the digit, the stronger the protection.
- Read the guide: IP ratings (IP44, IP55, IP65): choosing a junction box or enclosure
- Junction box
- An enclosure where cables are joined. Its IP rating is chosen for the location: dry indoors, sheltered outdoors or fully exposed.
- Read the guide: IP ratings (IP44, IP55, IP65): choosing a junction box or enclosure
- Module (distribution board)
- The width unit of the devices on a board's DIN rail, 17.5 to 18 mm. The number of modules gives the space available, not the number of circuits.
- Read the guide: 12-, 24- or 36-module distribution board: how many modules for a home or a shop?
- Rated current
- The current at full output, in amperes: kVA × 1,000 / (√3 × voltage) on three-phase. It sizes the cables and the circuit breaker.
- Read the guide: Writing a generator specification for a tender in the DRC
- Single-phase
- A supply on one phase and a neutral, 220 V in the DRC. Most houses are supplied this way.
- Read the guide: Single-phase or three-phase generator: how to choose
- Three-phase
- A supply on three phases, 380 V in the DRC, for motors and commercial installations. Loads must be spread across the phases.
- Read the guide: Single-phase or three-phase generator: how to choose
- Booster pump
- A pump that raises the pressure of mains or tank water for the taps of a house.
- Read the guide: Low water pressure at home: booster, peripheral or jet pump?
- Centrifugal pump
- A surface pump that gives more flow and less head than a peripheral pump. A multistage pump chains several impellers to lift higher.
- Read the guide: Which water pump for a house in Kinshasa?
- Engine-driven water pump
- A pump driven by a combustion engine, to move large volumes of water without electricity. Its size in inches is the outlet diameter (1 inch = 25.4 mm).
- Read the guide: 2-, 3- or 4-inch petrol water pump: which one for irrigation, draining or transfer?
- Flow rate
- The volume of water pumped per unit of time, in m³/h or L/min. A datasheet's maximum flow is reached at almost zero head.
- Read the guide: Which water pump for a house in Kinshasa?
- Jet pump
- A self-priming surface pump that draws water from deeper than a standard surface pump.
- Read the guide: Which water pump for a house in Kinshasa?
- Peripheral pump
- A surface pump that gives high pressure at low flow, suited to tanks placed high up.
- Read the guide: Which water pump for a house in Kinshasa?
- Suction lift
- The depth from which a surface pump can draw water. The physical limit at sea level is about 10 m of water; deeper, the pump must sit in the water.
- Read the guide: Which water pump for a house in Kinshasa?
- Sump pump
- A submersible pump that lifts water from a pit below the drain. With a float switch it starts and stops on its own with the water level.
- Read the guide: Flooding, pits and basements: which submersible pump to drain the water?
- Total head
- The height the pump must lift water, plus the friction losses in pipes, bends and valves. 10 m of water is about 1 bar.
- Read the guide: Which water pump for a house in Kinshasa?
- Turnover time (pool)
- The time it takes for the whole pool volume to pass through the filter. The volume divided by that time gives the pump flow needed.
- Read the guide: Pool pumps: what flow rate for your pool volume?
- Air delivery (compressor)
- The amount of air a compressor produces each minute, in L/min. It decides whether an air tool can run continuously.
- Read the guide: Air compressors for a garage or workshop: which airflow, pressure and tank size?
- Engine displacement
- The volume swept by the engine's piston or pistons, in cm³ (cc). A 150 cc motorcycle has an engine of about 150 cm³.
- Read the guide: 150cc motorcycles in Kinshasa: understanding the spec sheet (Toyama, Brux, Simba, Volcan)
- Plate compactor
- A machine that compacts soil or paving by vibration. Its compaction depth is the layer thickness it handles effectively.
- Read the guide: Plate compactor, rammer or roller: which compactor for which job?
- Rammer
- A narrow-footed compactor that pounds the ground. It works better on clay soils, where a plate tends to bounce.
- Read the guide: Plate compactor, rammer or roller: which compactor for which job?
- Welding generator
- A machine that combines an engine, a welding source and a small generator, to weld on site without grid power. The welding current is chosen for the largest electrode.
- Read the guide: Diesel welding generators: welding on site without grid power