CORE AS 6I2432 - Caterpillar

The Energize-To-Run (ETR) system and the Energize-To-Shutoff (ETS) system are electric protection systems for engines. The electric protection system will protect the engine from damage if an engine operating function is not within a safe limit. When the engine is purchased, the customer specifies the electric protection system that is installed on the engine.When the electric protection system detects an unsafe limit, the system will energize the fuel solenoid or the system will de-energize the fuel solenoid. If the engine is not equipped with a fuel solenoid, the 2301A Electric Governor Control may be controlled by the electric protection system. An unsafe limit is called a fault.The basic difference between the ETR system and the ETS system is the operation of the fuel solenoid. The ETR system de-energizes the fuel solenoid in order to stop the fuel flow which causes engine shutdown. The ETS system energizes the fuel solenoid in order to stop fuel flow which causes engine shutdown.The ETR system requires the fuel solenoid to be energized in order for the engine to run. The fuel solenoid must be energized before the fuel is allowed to flow to the engine cylinders. After the engine starts and runs, a normal shutdown or a problem with any of the engine functions that are monitored will cause the fuel solenoid to be de-energized. When the fuel solenoid is de-energized, the fuel flow to the cylinders is stopped. This action causes engine shutdown.The ETS system requires the fuel solenoid to be de-energized in order for the engine to run. The fuel solenoid must be de-energized before the fuel is allowed to flow to the engine cylinders. After the engine starts and runs, a normal shutdown or a problem with any of the engine functions that are monitored will cause the fuel solenoid to be energized. When the fuel solenoid is energized, the fuel flow to the cylinders is stopped. This action causes engine shutdown.The 2301A Electric Governor Control operates in the same manner in the ETR system and in the ETS system. When the governor control system is installed, the fuel solenoid is not used. When a fault occurs, the governor control system is de-energized. This causes the fuel control linkage to stop the fuel flow to the engine.The ETR system and the ETS system use two or three engine components in order to monitor as many as six engine operating functions:
Engine overspeed (OS) which is monitored by the electronic speed switch
Crank termination which is monitored by the electronic speed switch
Oil step latch which is monitored by the electronic speed switch (3500 Series Engines)
Engine oil step pressure which is monitored by the electronic speed switch (3500 Series Engines)
Water temperature (WT) which is monitored by the water temperature contactor switch
Oil pressure (OP) which is monitored by one or two oil pressure switches.Overspeed protection monitors the engine from starting through 118% of rated speed. An engine that is equipped with all three components is called Full Protection System.An engine which does not have