Dictionary of Electrical Engineering

Commonly used terms in the Electrical industry.

hot tap
a clamp, applied with a hot stick that connects a branch circuit to an existing conductor and typically applied while the system is energized.
load tap changer (LTC)
a tapped transformer winding combined with mechanically or electronically switched taps that can be changed under load conditions. The load tap changer is used to automatically regulate the output of a transformer secondary as load and source conditions vary.
no load tap changer
device that provides for changing the tap position on a tapped transformer when the transformer is de-energized. Different taps provide a different turns ratio for the transformer.
a connection (actually one of several) to a coil, allowing the number of turns in the coil to be varied.
tap changer
a device to change the tap setting on a transformer coil, allowing voltage control. See also tap, tap changing under load.
tap changing under load (TCUL)
a type of transformer in which the output voltage can be adjusted while the load is connected to the transformer. The voltage is adjusted by changing the turns ratio of the primary and secondary coils. That, in turn, is accomplished by bringing out connections (taps) at several points on the coil. Changing from one tap to another either adds or subtracts turns from the coil and raises or lowers the voltage, respectively.
tape-wound core
a ferromagnetic core constructed by winding ribbon-like steel instead of stacking thicker, punched lamination. Usually used for higher frequency devices, or where it is desired to reduce the eddy current losses.