Should the engine be stopped automatically on low oil pressure and high temperature?
Yes, low oil pressure and high coolant temperature are the basic protection pair and they should stop the engine. The oil pressure switch closes to chassis in the fault condition and stays open if pressure is sufficient. Common standard thresholds for temperature switches are 100 °C, 135 °C, 150 °C and 200 °C. The GS740 and GS740-3P have no engine protection input; this chain must be built separately.
The protection logic is simple: the switches change the circuit in the fault condition, and this signal releases the fuel shut-off solenoid and stops the engine.
- Oil pressure switch: open under pressure, closes to chassis when pressure drops. A delay is needed on first start until pressure builds up, otherwise the engine can never run.
- Temperature switch: normally closed types are common; they change state when the threshold is exceeded. Choose one matching the threshold specified by the engine manufacturer.
- Chain: the emergency stop button, the oil pressure and the temperature switches are combined in the same shutdown circuit.
Do not count the speed control kit as part of this chain. The GS740 and GS740-3P drive throttle lever position; they do not measure oil pressure, temperature or engine speed, they have no inputs for these, and they cannot stop the engine in a fault condition. These two protections must be present in every stationary diesel installation, with or without the kit.
Full topic: Electronic speed and throttle control on a diesel engine