Solenoids - Briggs & Stratton 86262GS Familiarization & Troubleshooting Manual

Portable Generator Familiarization & Troubleshooting Guide
Section 2 • Generator Components & Systems
Some stators may have a thermal protector imbedded in
their wire windings and electrically connected in series with
the excitation winding output to the voltage regulator.This
thermal switch opens at a pre-determined temperature to
terminate excitation current output to the rotor.The switch
closes automatically when the internal stator temperature
decreases to a safe value (Figure 2.24).
Figure 2.24 — Thermal Protector
Another type of thermal switch may sense engine coolant
temperature.This switch is the "normally-open" (NO) type
and closes if coolant temperature exceeds a pre-determined
safe value. It grounds the engine's ignition circuit and causes
the engine to shut down.
Pressure Switches
One example of a pressure switch is the low oil pressure
shutdown switch used on some generator engines.This type
of switch is normally-closed (NC), and is held open by
engine oil pressure during engine operation. Should engine
oil pressure drop below a pre-determined safe value, the
switch closes to ground the engine ignition circuit, causing
the engine to shut down (Figure 2.25).
Figure 2.25 — Typical Pressure Switch

Solenoids

A solenoid is a device used to convert electrical energy into
mechanical movement. It is based on the principle that when
current flows through a conductor, a magnetic field is
created around that conductor. Solenoids may be used in the
following applications:
• Fuel shutoff valves
• Electric chokes
• Engine throttle controls
• Engine anti-dieseling devices.
Fuel Shutoff Valves
This type of valve is energized open by a 12VDC signal
during engine cranking and running. A spring causes it to
close when the (DC) signals are removed as the engine
shuts down (Figure 2.26).
Figure 2.26 — Typical Fuel Shutoff Valve
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