Abbreviations and technical terms frequently found in the power industry, on solar power plants and on this website — explained briefly and clearly. If you can't find the term you need or want details specific to your site — write to us and we'll explain.

Substations, switchgear and distribution

The main equipment for stepping down voltage and distributing electricity across a site.

transformer substation: A complex with a transformer for changing voltage and distributing electricity.
KTP: Package (complete) transformer substation — KTP steps down 6(10) kV to 0.4 kV to supply a site.
BKTP: Block-type (concrete) package transformer substation.
KTPB: Package transformer substation of block-type design.
STP: Pole-mounted transformer substation.
ZTP: Indoor transformer substation (housed in a building).
power transformer: A high-capacity transformer that changes voltage for distribution among consumers.
transformer: A device that changes the voltage level of electricity for transmission or consumption.
transformation ratio: The ratio of transformer windings that sets the multiplier for the change in current or voltage.
GRSHch: Main 0.4 kV distribution switchboard — the main distribution point across a site.
KRU: Package medium-voltage switchgear unit.
KRUN: Package switchgear unit for outdoor installation.
KRPZ: Package switchgear unit (protected design).
KSO: Single front-access switchgear cabinet — a 6–10 kV switchgear cubicle.
RUNN: Low-voltage switchgear (0.4 kV).
RU: Switchgear — equipment for distributing electric power within a network.
RP: Distribution point — an intermediate station for distributing electricity.
VRP: 0.4 kV incoming-distribution device (incoming feed + metering + protection).
VRU: Incoming distribution device — a cabinet that controls the electricity supply and its distribution.
NKU: Low-voltage package device — a switchboard for distribution at 0.4 kV.
RUVN: High-voltage switchgear — a cabinet with breakers at a substation's input.
YaVU: Incoming-metering box for small sites.
ShchO-90: Lighting panel of the ShchO-90 series.
cubicle: A separate compartment in a substation cabinet holding the equipment for one line.
busbar system: A system of copper or aluminum bars for distributing current within a switchboard.
busway: A structure made of busbars for carrying high currents in switchboards and substations.

Switching and protection

Devices for turning circuits on and off and for automatic protection against overloads and short circuits.

AVR: Automatic transfer switching (ATS) — switches to a backup feed or a generator.
RZA: Relay protection and automation — disconnects equipment on a short circuit or overload.
circuit breaker: A breaker that trips automatically on a short circuit or overload.
load-break switch: A device for switching a circuit on/off during normal operation (not for faults).
fuse: A protective device that breaks a circuit on excessive current, preventing fire.
relay: An automatic device that trips under set conditions to protect equipment.
contactor: An electromagnetic device for remote switching of high-power circuits on and off.
switching device: A device for turning electrical circuits on and off (breakers, contactors).
trip unit: The mechanism of a circuit breaker that trips it on excessive current.
vacuum circuit breaker: A breaker that interrupts a circuit in a vacuum, without arcing.
disconnector: A device for opening a circuit with no load, for safe maintenance.
ATS: Automatic transfer switch between the grid, a generator and a battery.
UPS: A system that instantly switches the power supply to batteries when the grid goes down.
surge arrester: A device that protects equipment from voltage surge spikes.

Solar power plants

Components and concepts for photovoltaic generation systems.

SES: Solar power plant.
grid-tied solar power plant: A solar plant that feeds electricity directly into the grid without batteries.
hybrid solar power plant: A solar plant that runs on solar power during the day and on batteries at night.
photovoltaic effect: The phenomenon whereby silicon generates electric current under light.
monocrystalline panels: Solar panels made from a single uniform crystal — high efficiency.
polycrystalline panels: Solar panels made from multiple crystals — cheaper but less efficient.
insolation: The amount of solar energy falling on a surface over a given period.
PVGIS: The European Commission's database for calculating solar generation by coordinates.
DC/AC oversizing: Installing panels with more capacity than the inverters; the excess is clipped at peak.
RES: Renewable energy sources — solar, wind and other environmentally friendly generation.

Energy storage (batteries)

Batteries and systems for storing energy and providing backup power.

BESS: Battery energy storage system. → резервне живлення
AKB: Battery — provides backup power during an outage in a hybrid solar power plant.
hybrid inverter: An inverter that runs on panels, batteries and the grid, switching between them.
BMS: Battery management system — controls charge, discharge and temperature for safety.
LiFePO4: Lithium iron phosphate battery: safe, thermally stable, high cycle life.
Li-NMC: Lithium nickel manganese cobalt battery: more compact, requires thermal control.
DoD: Depth of discharge — the share of battery capacity that can be used without damage.
C-rate: The charge/discharge rate of a battery (1C = a full cycle in one hour).
backup power: Automatic power supply from batteries during an outage of the main grid.
DGU: Diesel generator set — a backup power source.
DBZh: Uninterruptible power supply (UPS).

Inverters and power conversion

Devices for converting and transforming electric current.

inverter: A device that converts direct current from panels/batteries into standard alternating current.
single-phase inverter: A single-phase inverter — for small houses and small installations.
three-phase inverter: A three-phase inverter — for industrial sites with high-power loads.
direct current: Electricity from panels or batteries that flows in one direction.
alternating current: Standard grid electricity that constantly reverses direction.
soft starter: A device that gradually brings an electric motor up to speed, reducing the inrush current.

Power engineering and the grid

Parameters, indicators and phenomena in electrical networks.

three-phase: An electrical system with three current phases — for industrial sites.
cos φ: Power factor; a low cos φ means paying a penalty for reactive energy.
reactive power: The portion of energy that does no useful work but circulates in the network.
reactive power compensation: Capacitors that reduce unneeded reactive power and save energy.
UKRM: Reactive power compensation unit — raises cos φ.
UKM: Reactive power compensation unit — raises cos φ.
rated power: The maximum power the equipment is designed for under normal operation.
KKD: Efficiency factor — the share of energy converted into useful output.
eddy currents: Currents induced in metal by a changing magnetic field, which heat it up.
contact resistance: Resistance at the point of contact between two surfaces; higher resistance means more heating.
AFR: Automatic frequency load shedding (a DSO system requirement).
curtailment: Restriction of energy output by the dispatcher when the grid is overloaded.
sectionalizing: Dividing a network into sections so a faulty one can be isolated without shutting down the whole network.

Money and project payback

Financial indicators, contracts and investment schemes for energy projects.

FX (currency risk): The effect of exchange-rate changes on a project's economics when costs are in foreign currency and revenue is in hryvnia.
CAPEX: Capital expenditure — money spent on purchasing and installing equipment.
OPEX: Operating expenditure — annual spending on maintenance and repairs.
TEO: Feasibility study — a calculation of a project's costs, payback and benefits.
payback: The period over which the profit from a plant returns the money invested in it.
IRR: Internal rate of return — the annual percentage return on an investment.
NPV: Net present value — future profits expressed in today's money.
TCO: Total cost of ownership — the sum of purchase and maintenance costs over the entire service life.
BOM: Bill of materials — a list of all components, quantities and prices.
leasing: Purchase of equipment by a finance company, which then hands it to the client for the payment period.
ESCO: Energy service company — the investor recoups costs from the energy savings achieved.
hedge: Insurance against risk through a reserve (batteries), which allows selling at better moments.
arbitrage: Storing energy during cheap hours and selling it during expensive hours.
Tier-1: The highest quality category of equipment from leading global manufacturers.

Market, grid connection and tariffs

Rules for entering the energy market, contracts and trading mechanisms.

capture price: The average market price specifically during the hours when your plant is generating. For solar power plants it is usually lower than the daily average, because the sun generates during the day, when supply is highest.
RDN: The day-ahead market — hourly trading of electricity.
Net Billing: Settlement for surplus energy in money, at market prices.
net-metering: Offsetting the surplus electricity fed into the grid against the electricity consumed.
PPA: A long-term power purchase agreement at a fixed price and volume.
Merchant: Selling electricity on the wholesale market without a long-term contract, at current prices.
DSO: Distribution system operator (the regional grid company).
NEURC: The National Energy and Utilities Regulatory Commission.
TU: Technical conditions for connecting to the electricity grid (issued by the DSO).
flexible connection: Connecting a plant to the grid without a major grid expansion, with output restrictions.
balancing market: The market where electricity is bought/sold to maintain the instantaneous balance of the grid.

Automation and dispatching

Systems for remote control, monitoring and automation of facilities.

ChRP: Variable frequency drive (frequency converter) — a device that smoothly changes the speed of a motor or pump. It reduces starting currents and allows output control.
dispatching: Remote monitoring and control of equipment from a single center in real time.
monitoring: Continuous observation of equipment parameters and alerts about problems.
SCADA: A system for remote control and monitoring of equipment via computer. → диспетчеризація SCADA
PLC: Programmable logic controller — carries out automatic control according to a program.
HMI: A panel for operator interaction with the control system.
mimic diagram: A simplified graphical diagram of facilities on a screen for the operator to view.
Modbus: An industrial protocol for data exchange between devices and controllers.
telemechanics: Remote monitoring and control of equipment via communication channels.
VOLZ: Fiber-optic communication line — a cable for transmitting data via light pulses.
microprocessor-based protection terminal: An electronic control and protection device replacing mechanical relays.
LoRaWAN: A long-range low-power wireless data transmission technology for sensors.
OTA update: Remote firmware update of a device without a site visit.
level sensor: A sensor for measuring the level of liquid in a tank.
flow meter: A sensor for measuring the amount of liquid or gas in a pipeline.
motorized gate valve: A shut-off mechanism with a motor for remote control of liquid flow.
twilight relay: A light sensor that turns lighting on in the dark and off in daylight.

Design, installation and documentation

Technical documentation, construction stages and facility approvals.

EDRPOU: The Unified State Register of Enterprises and Organizations of Ukraine. An EDRPOU code is a legal entity's registration number, needed among other things for applying for technical conditions.
EPC: Turnkey construction: design, supply and installation by a single company.
EPC contractor: A company that designs, supplies equipment for, and builds a facility turnkey.
PNR: Commissioning works carried out before a facility is put into operation.
commissioning: The official start-up of a facility and its handover into regular operation.
single-line diagram: A simplified drawing in which the three phases are shown as a single line for clarity.
schematic diagram: A detailed diagram of all circuit elements with the function of each one marked.
as-built documentation: Certificates confirming that work was carried out correctly and that the system is ready.
technical questionnaire: A customer document listing the parameters and components for the switchgear manufacturer.
BMR: Construction and installation works — assembling structures and equipment on site.
geodesy: Surveying and analysis of a site for correct placement of facilities.
geological survey: Investigation of soil and groundwater to assess suitability for construction.
HDD: Horizontal directional drilling — laying cables under roads without excavation.
bentonite: A clay-based fluid that stabilizes and cools the tool during drilling.
DIN rail: A standard rail inside a switchboard for mounting modular equipment.
sandwich panel: A construction panel with insulation between two metal sheets.
torque wrench: A tool that tightens bolts with precisely controlled force.
tightening torque: The force with which a bolt or nut is tightened, to ensure a reliable connection.

Codes and standards

The regulatory framework, rules and requirements for electrical installations.

PUE: Electrical Installation Regulations — the primary regulatory document.
PTEE: Technical Operating Rules for Electrical Installations — standards for maintenance and repair.
DSTU: DSTU (Ukrainian national standards).
DBN: State Construction Norms.
IEC: International Electrotechnical Commission — global standards for electrical equipment and safety.
ASKOE: Automated system for commercial electricity metering.
OVD: Environmental impact assessment — the procedure for documenting a facility's impact on nature.
first reliability category: Facilities that require uninterrupted power supply from two independent feeds.

Cable lines and grounding

Wiring, surge protection and safe connection to earth.

cable routes: Cable-laying routes that comply with safety and maintenance standards.
insulation: A protective layer (rubber, plastic) that prevents current leakage and contact with it.
insulation resistance: An indicator of a cable's protective-layer quality: higher means safer and more durable.
grounding: A safe connection of equipment to earth for diverting fault current.
lightning protection: A system of rods and grounding that diverts a lightning strike into the ground.

Measurement and control

Current/voltage transformers and instruments for energy metering.

current transformer: A device that reduces line current to a level safe for measurement and protection.
voltage transformer: A device that reduces line voltage to a level safe for measurement and protection.
accuracy class 0.5S: The accuracy of a current transformer for energy metering: error up to 0.5%.
motor-hours: The total running time of a motor, for monitoring its service life and planning maintenance.

Other terms

dry running: Operation of a pump without liquid, leading to overheating and failure.
water hammer: A sharp pressure surge in a pipe caused by a sudden stop in flow.

Glossary: electrical engineering abbreviations in plain terms