Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

static VAR regulator
also called a static VAR compensator. A nonrotating electrical device designed to adjust the reactive power flow of an AC power system. It typically consists of a reactive load (either inductive or capacitive) and a series electronic switch (thyristor) that controls the reactive power.
station battery
a battery used to provide operating energy for the protective relay operations and to initiate circuit breaker operations in a generating station. The battery is necessary, as the equipment must work reliably during severe voltage sags and outages on the AC system.
station control error
in economic dispatch studies, the difference between the desired generation of all plants in a control area and the actual generation of those plants.
station insulator
refers to a large-sized insulator used in substations.
steady-state control
operation and mechanisms of the control system in which the main objective is to keep the controlled process in the condition where the state variables relevant to the controlled process performance are constant i.e., to keep the process in a required operating point. Steady-state control structure may be composed of several control layers, including direct regulatory layer, optimization layer and, eventually, other layers; steady-state control is widely used in chemical and power industries.
steady-state gain
the gain that a system applies to DC (constant) input signals.
step voltage
in power system safety studies, the voltage measured across two points on the ground which are separated by a distance equal to an average person's step while walking over the area in question.
step-down converter

See buck converter
step-up converter

See boost converter
strain insulator
an insulator which forms an insulated tensile link between two conductors in overhead line work.
submersible transformer
a transformer, used in underground distribution work, which is capable of operation while submerged in water.
substation
a junction point in the electric network. The incoming and outgoing lines are connected to a busbar through circuit breakers.
substation battery
a battery used to provide operating energy for the protective relay operations and to initiate circuit breaker operations in a generating substation. The battery is necessary, as the equipment must work reliably during severe voltage sags and outages on the AC system.
subsynchronous resonance
an electric power system condition where the electric network exchanges energy with a turbine generator at one or more of the natural frequencies of the combined system below the synchronous frequency of the system.
subtractive polarity
polarity designation of a transformer in which terminals of the same polarity on the low-and high-voltage coils are physically opposite each other on the transformer casing. With subtractive polarity, a short between two adjacent terminals results in the difference of the two coil voltages appearing between the remaining terminals.
Subtractive polarity is generally used on transformers larger than 500 kVA and higher than 34.5 kV. Smaller units use additive polarity.
See additive polarity
subtransient current
the fault current that flows during the subtransient period when the generator and motor apparent impedances are their respective subtransient impedances.
subtransient impedance
the series impedance that a generator or motor exhibits during the subtransient period, typically the first few cycles of a fault. Subtransient impedances are generally used in calculating fault currents for determining instantaneous relay settings.
subtransient open-circuit time constant
See quadrature-axis transient open-circuit time constant and direct-axis subtransient open-circuit time constant.
subtransmission
the circuits which connect bulk power substations to distribution substations.
subway transformer
another name for a submersible transformer.
Powered by The Filipino Engineer