There are many terms associated with the power distribution and transformer industry.
And, all of us at JCL Energy wanted to offer a helping hand with some of the most common.

JCL Shoot 8-10-20-20
JCL Shoot 8-10-20-25
Terminology A - E

Alternating Current (AC): An electrical current flow of continuously changing polarity, which rises to a maximum voltage in one direction, decreases to zero and then sinks to the maximum voltage in the other direction before changing polarity once again. This pattern is referred to as a sinusoidal wave and the number of cycles per second is equal to the frequency, which is measured in “Hertz”.

Ambient Temperature: The normal surrounding temperature of the environment in which a transformer will operate.

Auto Transformer: A transformer used to step voltage up or down. The primary and secondary windings share common turns and thus provide no electrical isolation.

ANSI: ANSI was formed in 1918. American National Standards Institute is a recognized body which approves standards for transformers. ANSI 89.1 is mostly used for dry type transformers.

Air Cooled Transformer: A transformer which uses air as the cooling medium. This may be a forced air with the use of fans.

Ambient Noise Level: The level of acoustic noise existing at a given location like room or compartment etc. Ambient noise level is measured based on sound level meter or in decibels (db).

Arc Voltage: The amount of voltage present between electrodes of different potential or between an electrode and ground. The magnitude is determined by the distance between electrodes and the dielectric constant of the medium surrounding them.

BIL Basic Insulation Level: It is an insulation system that can withstand very high voltage surges.

Breakdown Voltage: The voltage at which an electrical breakdown occurs. It is also known as breakdown potential, sparking potential or sparking voltage.

Core: The ferrous center part of a transformer or inductor used to increase the strength of the magnetic field. It carries the flux and forms the magnetic coupling between primary and secondary

Core Saturation: Condition that occurs when an inductor or transformer core has reached maximum magnetic strength.

Current Transformer (CT): A transformer used in instrumentation to assist in measuring current. It utilizes the strength of the magnetic field around the conductor to form an induced current that can then be applied across a resistance to form a proportional voltage.

Compensated Transformer: A transformer with a turn’s ratio which provides a higher than rated voltage at no load, and, rated voltage at rated load.

Core Loss: Core loss is also known as iron loss. Core loss is a form of energy loss that occurs in electrical transformers and other inductors. Core losses do not include the losses due to resistance in the conductors of the windings, which is often termed copper loss. It does not vary with load and hence also called constant losses. It mainly consists of eddy current and hysteresis losses.

Delta: Delta is a three phase connection where the ends of each phase winding connection in series to form a closed loop with each phase 120 electrical degrees from the other.

Delta-Delta: The connection between a delta source and a delta load.

Delta-Wye: The connection between a delta source and a wye load.

Drive Isolation Transformer: A transformer built with a K factor of K4 or greater and an electrostatic shield. Drive isolation transformers are designed this way to mitigate the negative affects of harmonics (caused by non-linear loads) on the transformer itself.

Duty Cycle: The percentage of time a transformer will be supplying the Full Rated Power to the load. Percentage of time a unit is expected to perform at Full Rated power versus time spent in idle can significantly affect the physical size of a transformer.

Electrostatic Shield: A grounded conductor sheet which provides a ground shield between primary and secondary windings to decrease or eliminate line to line or line to ground noise. It is also known as Faraday Shield.

Effective Voltage or Current: The amount of power being delivered to a DC circuit load can be calculated easily by dividing the load resistance into the applied DC voltage squared.

Eddy Currents: It is induced into a metal when magnetic lines of force move across it.

Efficiency: Ratio of its power output to its total power input

Excitation Current: Current required magnetizing a core..

Electrostatic Shielding: Placed between windings (usually the primary and secondary) to provide maximum isolation. Additional Electrostatic Shields can be placed between secondary windings as required. Shielding is normally connected to the transformer’s ground.

Encapsulation: A process in which a transformer or one of its components is completely sealed with epoxy or a similar material. This process is normally performed when a unit might encounter harsh environmental conditions such as moisture, salt spray, full-water submersion or corrosive elements.

Exciting Current: The current drawn by a transformer at nominal input voltage in its unloaded (open-circuit) condition.

Terminology F - J
Terminology K - P
Terminology R - Z
JCL Energy

Your "people first" electrical
equipment provider!


JCL Energy
892 S Dock St., Sharon, PA 16146


Follow Us


Copyright © 2020 JCL Energy. All rights reserved. Privacy Policy.