Table of Contents
Advertisement
Permanent Magnetic Generator (PMG) — The PMG
eliminates the excitation losses in the rotor, which otherwise
typically represent 20–30% of the total generator losses. It
also gives a lower temperature rise in the generator.
Rheostat (VR) — Electrical resistor used to control a
current by varying the resistance.
Short Circuit — An electrical circuit that allows current
to travel along a different path from the one originally
intended. The electrical opposite of a short circuit is an
open circuit, which is an infinite resistance between two
nodes.
It is common to misuse the term 'short circuit' to describe
any electrical malfunction, regardless of the actual problem.
Damage from short circuits can be reduced or prevented
by employing fuses, circuit breakers, or other overload
protection, which disconnect the power in reaction to
excessive current.
Single-Phase (1Ø) Power — Is typically 120 or 240
VAC that is carried between two wires, line and neutral
and a third ground wire for safety. The frequency of the
AC voltage is typically 60 Hz. 1Ø power is used in many
applications. For example, 1Ø power is used to power all
typical home electrical appliances.
Sound Level — Generator sound level is measured in
decibels (dB). Ratings are typically published at 23 feet
(7 Meters)
Surge Protection Components — Surge protection
devices attempt to regulate the voltage supplied to an
electric device by either blocking or by shorting to ground
voltages above a safe threshold.
• Varistor —An electronic component with a "diode-like"
voltage characteristic. Varistors are used to protect
circuits against excessive transient voltages by
incorporating them into the circuit in such a way that,
when triggered, they shunt the current created by the
high voltage away from the sensitive components.
A varistor is also known as a voltage dependent
resistor (VDR). A varistor's function is to conduct
significantly increased current when voltage is
excessive.
GENERATOR SERVICE AND TROUBLESHOOTING MANUAL — REV. #0 (08/29/23) — PAGE 73
• Metal Oxide Varistor — The metal oxide varistor
(MOV) contains a material, typically granular zinc oxide
that conducts current (shorts) when presented with a
voltage above its rated voltage. MOVs typically limit
voltages to about 3 to 4 times the normal circuit voltage
by diverting surge current elsewhere.
MOVs have finite life expectancy and 'degrade' when
exposed to a few large transients, or many more
smaller transients. Degrading is the normal failure
mode. MOVs that fail shorted are so small as to violate
the MOV's absolute maximum ratings. MOVs usually
are thermal fused or otherwise protected to avoid short
circuits and other fire hazards.
• Zener Diode — A silicon semiconductor device that
permits current to flow in either a forward or reverse
direction. The diode consists of a special, heavily
doped P-N junction, designed to conduct in the reverse
direction when a certain specified voltage is reached.
• Diode — An electrical component that allows the
current to flow in only one direction. It may be used
as a rectifying element.
Three-Phase AC Power — Three-phase AC power is
a type of polyphase system employing three wires (or
four including an optional neutral return wire). Voltage is
carried through three conductors 120° out of phase with
the other two. Three-phase AC power. provides a more
efficient means of supplying power to large electrical loads
like motors
Volt-Ampere (VA) — An International System (SI) unit for
the apparent power in an electrical circuit. The apparent
power equals the product of root mean square voltage (in
volts) and root mean square current (in amperes).
Voltage (V) — The difference of electrical potential between
any two conductors.
Voltmeter — Measures voltage, current, and resistance
in electronic circuits. Also used to perform continuity tests.
Watt (W) — An International System (SI) unit of power
equal to one joule per second, the power dissipated by
a current of 1 ampere flowing across a resistance of 1W.
DEFINITIONS
Advertisement
Table of Contents
