Xl And Mc Idle Control On 480 & 570 V-Twin Engines - Briggs & Stratton 86262GS Familiarization & Troubleshooting Manual

Portable Generator Familiarization & Troubleshooting Guide
Section 2 • Generator Components & Systems
XL And MC Idle Control On 480 & 570 V-Twin
Engines
Figure 2.89 shows the stepper motor used on the
V-Twin GN-Engines.
Figure 2.89 — Stepper Motor
Figure 2.90 shows the idle control transformer, housed in
the generator control panel.This is the same transformer
used on single cylinder GN-engines.
Figure 2.90 — Idle Control Transformer
Idle control operation is controlled by the idle control
circuit board, which is housed in the generator control panel
(Figure 2.91). Power for system operation is taken from the
generators 12VDC, 10 amp battery charge winding. Power is
available to the circuit board for idle control system
operation any time the generator is running.
With the idle control switch ON (closed), and no electrical
loads connected to the generator, operation may be
described as follows:
• Current does not flow through the primary windings of
the idle control transformer and no current flow will be
induced into the transformer's secondary windings.
• The idle control board will "sense" there is no load on
the generator and will send a signal to the idle control
stepper motor.
• The stepper motor will move to the low idle position,
which will move the governor linkage, reducing
governor spring tension, and lowering engine speed to
idle (about 40-45 Hertz).
Figure 2.91 — Stepper Motor
When an electrical load is applied to the generator:
• Current will flow through the idle control transformer's
primary windings, inducing a current in the secondary
windings
• The idle control board "senses" this current via wires
155 and 156.
• It sends a signal to the idle control stepper motor to
move to the high speed position.
• This moves the governor linkage, increase governor
spring tension and increases engine RPM to normal
governed speed.
When the idle control switch is set to OFF (open):
• The circuit board moves the stepper motor to the high
speed position.
53