GENERATOR

Portable Generator Familiarization & Troubleshooting Guide
Section 2 • Generator Components & Systems
Figure 2.87 shows the idle control transformer which is
housed in the generator control panel.
Figure 2.87 — Idle Control Transformer
• When electrical loads are applied to the generator,
current will flow through the transformer’s primary
windings, inducing a current in the secondary windings.
The system control board senses this current via wires
155 and 156. It then opens the circuit to the idle
control coil.That coil will de-energize and the engine
will return to normal governed speed.
When the idle control switch is set to OFF (open), the
circuit board is not powered and no power is available to
energize the idle control solenoid.The solenoid will then
remain in a de-energized state whether electrical loads are
connected or not.The engine will then always run at normal
governed speed.
Figure 2.88 — Idle Control Schematic
Operation may be briefly described as follows:
Idle control operation is controlled by the multi-function
system control board, which is housed in the generator
control panel (Figure 2.88). Power for system operation is
taken from the stator’s 120VAC power windings and
delivered to the circuit board via wires 11, 22 and the idle
control switch.
With the idle control switch ON (closed) power is available
to the circuit board for idle control system operation.
• When no electrical loads are connected to the
generator, current does not flow through the primary
winding of the idle control transformer. Consequently,
no current flow will be induced into its secondary
windings. System control board action will then
complete (close) the circuit to the idle control coil,
delivering 120VDC to the coil.With the coil energized,
the governor lever will be pulled in to reduce engine
speed to idle (about 40-45 Hertz).
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