# Electrical Engineering Terms H

High Voltage (High Tension).

A general term used to describe circuits with system voltages greater than 600 volts and to imply that the voltage is of such a value that it is dangerous to humans. Extreme caution should always be used when troubleshooting equipment marked with this term.

Horsepower (HP)

Horsepower is a measure of the work output of a motor (electrical or otherwise). The metric conversion is 1 HP = 736 Watts.

Hermetic Refrigerant Motor-Compressor.

This type of electrical utilization equipment is a combination of a piston-type compressor and an electric motor, both of which are enclosed in the same housing, with no external shaft or shaft seals (hermetically-sealed): the motor operates in the refrigerant.

Hertz (Hz).

Cycles per second. Normally abbreviated to the acronym Hz, the unit of measure of the frequency of an AC source.

Horsepower (HP).

Normally abbreviated to the acronym HP, the nameplate value of torque an electric motor can produce when operated at its running or baseline speed at its nameplate rated voltage and frequency.

High-Leg Delta Connection.

Also referred to as a red-leg delta connection, this is a dual-voltage, 3-phase AC, 4-wire delta transformer wiring configuration in which the transformer connected between phases A and C (lines 1 and 3) is center-tapped and grounded. The center phase or B-phase conductor operates at a voltage-to-ground (neutral) value that is theÖ3 greater (1.732 or 1.73% greater) than voltage-to-ground of either phase A or phase C. This leg must be permanently identified with or to the color orange.

Hysteresis. Caused by the field reversal (continual de-magnetization and re-magnetization in opposite pole polarities) of the iron core by the sinusoidal electromagnetic field, hysteresis generates heat by molecular friction in the iron.

Hertz (Hz)

The unit for frequency, 1 Hz equals one cycle per second.