Glow Plug System: Description and Operation

The pencil element glow plugs consist of a housing, with a heater bar, and external threads. The electrical connection is maintained by a non-releasable brass nut. The heating element consists of a heating and control winding connected in series. When the glow plug system is turned on, a current of approx. 30 amps will flow per glow plug. The winding increases its resistance with increasing temperature and limits the current to approximately 8 - 15 amps. This will protect the glow plug against overload. The glow plugs are designed for a voltage of 11.5 volts and are operated as a parallel circuit. After a glow time of 9 seconds, a heater bar temperature of approximately 1500°F (900°C) will be attained.