Section II. ENGINE OVERSPEED RELAY
the engine to stop.
On model CMU-5 shop sets
overspeed is sensed by the resistor which trips the relay
The engine overspeed relay is a safety device that is
switches, causing the engine to stop.
controlled by the speed of the generator welder
armature. The exciter voltage is increased as the speed
29. Engine Overspeed Relay, Model SECM
of the armature is increased. On model SECM shop
sets the relay solenoid is adjusted so that excessive
a. Removal. Components of the overspeed relay
exciter voltage will cause it to actuate. The solenoid
can be removed while the box is in place; however, for
plunger trips a microswitch that is connected in series
with the engine ignition switch. When the microswitch is
TM 5-4940-200-12 to remove the engine overspeed
tripped, the engine ignition circuit is interrupted, causing
relay from the shop set body.
Figure 9. Engine overspeed relay resistor, microswitch, solenoid,
and terminal block, model SECM, removal and installation.