Electric Protection System Energize-To-Run For Generator Set, Industrial and Marine Diesel Engines Caterpillar

Illustration 1	g00290899
ETR Junction Box with oil pressure protection (OP) and water temperature protection (WT) that does not require a switchgear for use on 3200 through 3400 Engines (1) Terminal strips (TS) (2) Wiring harness (3) Junction box (4) Identification foil (5) Jumper between terminals (TS-3) and (TS-4) (6) Jumper between terminals (TS-4) and (TS-5) (7) Jumper between terminals (TS-5) and (TS-6) (8) Emergency stop switch (ES) (9) Jumper between terminals (TS-28) and (TS-29) (10) Jumper between terminals (TS-30) and (TS-31) (11) Slave relay (SR1) (12) Slave relay (SR2) for air shutoff solenoid (ASOS) (13) Grommets for engine oil pressure switches (14) Start/stop switch (SSS) (15) Slave relay (SR3) for starting aid switch (if equipped) (16) Circuit breakers (17) Mounting brackets for grommets (18) Engine oil pressure switch (OPS1)

Introduction

The ETR Junction Box with oil pressure protection (OP) and water temperature protection (WT) that does not require a switchgear is a system that has full protection. The system has a junction box arrangement that is designed to monitor four functions:

• Oil pressure

• Coolant temperature

The junction box includes the following components:

• Start/stop switch (SSS) (14)

• Slave relay (SR1) (11)

• Slave relay (SR2) (12)

• Oil pressure switch (OPS1) (18)

• Emergency stop switch (ES) (8)

The components that are listed below operate with the junction box. The components are also mounted on the engine.

• Fuel shutoff solenoid (FSOS)

• Water temperature switch (WTS)

The slave relay (SR1) must be energized in order for the engine to run with the ETR electric protection system.

An air shutoff solenoid (ASOS) is not used because the engine overspeed is not monitored.

Note: If the customer installs a mechanical overspeed switch on the engine, remove the jumper between terminals (TS-3) and (TS-4) on the terminal strip of the junction box.

Electrical Schematics and Wiring Diagrams

This manual contains the point-to-point wiring diagrams for the complete electric protection system and the junction box. Four types of electrical schematics for each electric protection system arrangement are shown in this service manual.

• Junction box wiring diagram

• IEC (International Electro-Technical Commission) schematic

• JIC (Joint Industrial Council) schematic

• Junction box wiring harness diagram

Note: The line number that follows a component code gives the location of the component on the IEC and JIC schematics.

Circuit Operation With No Faults

Engine Shutdown

When the engine is stopped, power is not available to any of the protection components. All switches are then in the normally open position or the normally closed position.

Engine Start-up

Illustration 2	g00282739
5N-0364 Switch (1) Keyway

A toggle switch is located on the front of the junction box. The switch is spring loaded and the toggle switch is automatically returned to the RUN. This happens when the toggle is manually released from the START position. This start/stop switch (SSS) has three positions:

• START (A)

• RUN (B)

• STOP (C)

When the start/stop switch (SSS) is moved to the START position, the following events should occur in the electric circuit.

1. The start/stop switch (SSS) closes the circuit to the starting motor.

2. The starter motor magnetic switch (SMMS) (line 9) closes a contact (line 3) which energizes the pinion solenoid (PS) (line 3).

3. The PS closes a contact (line 2) which energizes the starter motor (SM).

4. The current flows from terminal (TS-21) through the water temperature switch (WTS) (line 14).

5. The SSS closes across the contacts (SSS-4) (line 21) and (SSS-5) (line 20).

6. The current flows through contacts (SR2-30) and (SR2-87a) (line 28) of the slave relay (SR2). This energizes the slave relay (SR1).

7. Slave relay (SR1) closes contacts (SR1-30) and (SR1-87) (line 43) which are normally open.

8. The fuel solenoid (FS) is energized by the events in the circuit that is described above. The FS then allows fuel to flow to the engine.

When the toggle of the start/stop switch is held in the START position, power is always available to the starter motor until the engine begins to run. When the engine begins to run, the crank terminate switch (CT) stops the current that runs to the starter motor. When the engine begins to run, move the start/stop switch to the RUN position. If the engine oil pressure is too low to open the oil pressure switch (OPS1), the contacts across terminals (OPS1-1) and (OPS1-3) (line 15) open after the 9 second time limit. The slave relay (SR1) (line 36) is energized and the engine will shut down. Refer to "Fault Circuit Operation" for the complete circuit description under these conditions.

Note: If an electric starting motor is not used and an alternator is not used to run the engine, connect the power source to the engine. Connect the positive lead of the power source to terminal (TS-1) and connect the negative lead to terminal (TS-28) of the junction box. If an electric starting motor is not used and an alternator is used, the battery can still be used to run the engine. Connect the battery cables to the studs for the power input which are located on the bottom of the power distribution box.

Engine Mounted Start/Stop Switch (EMSS)

Illustration 3	g00281973
Engine mounted start/stop switch (typical example) (1) OFF position with switch terminals (B) and (C) closed. (2) ON position with switch terminals (B) and (R) closed. (3) START position with switch terminals (B), (R), and (S) closed.

Some engines use an engine mounted start switch (EMSS). The EMSS replaces the start/stop switch (SSS) and the contact (line 3) for the starting motor magnetic switch (SMMS). If an engine mounted start/stop switch is provided on the engine to control the electric starting motor, the start/stop switch (SSS) will not be installed in the junction box.

The EMSS is a start/stop switch which functions in the same manner as the SSS. When the lever of the EMSS moves to the START position, the pinion solenoid (PS) (line 3) is energized. The contacts (line 2) of the PS close. This energizes the starter motor (SM). The lever of the EMSS must remain in the START position until the oil pressure is observed before releasing the switch lever.

Engine Operation

When the engine is running under normal conditions and the SSS in the RUN position, the electrical current flows to the following components:

1. The current flows from terminal (TS-21) through the water temperature switch (WTS) (line 14).

2. Current flows through the contacts (SSS-4) and (SSS-5) (line 20) of the SSS that are closed to the oil pressure switch (OPS1).

3. Current flows through the contacts (OPS1-1) and (OPS1-2) (line 24) of (OPS1) that are closed.

4. The current then flows through diode (D1) in order to energize the slave relay (SR2).

5. When (SR2) is energized, the relay opens the circuit across the contacts (SR2-30) and (SR2-87a) (line 28). The relay closes the circuit across contacts (SR2-30) and (SR2-87) (line 27). This provides an alternative path for the circuit in order to keep the slave relay (SR2) energized.

6. Current also flows through the diode (D2) (line 27) in order to keep the slave relay (SR1) (line 28) energized.

7. The energized (SR1) keeps the fuel solenoid (FS) (line 30) energized even though the circuit across the contacts (SR2-30) and (SR2-87a) (line 28) is open.

The system is now armed and a fault with the coolant temperature or the engine oil pressure will automatically cause engine shutdown.

Normal Stop Switch

The engine is stopped by moving the start/stop switch. The switch is moved from the RUN position to the STOP position.

The following events occur in the electric circuit when the start/stop switch is moved to the STOP position.

1. The start/stop switch opens across contacts (SSS-4)and (SSS-5). The switch closes across contacts (SSS-5)and (SSS-6) that de-energize the slave relay (SR1).

2. The slave relay (SR1) then opens the contacts across (SR1-30) and (SR1-87) which de-energizes the fuel solenoid (FS).

3. The de-energized FS stops the fuel flow to the engine.

Note: When a remote normal stop switch (RNSS) is used, remove the jumper between (TS-4) and (TS-5) on the terminal strip of the junction box.

The circuit of this system is wired so that the engine can be immediately restarted.

Emergency Stop Switch (ES)

The emergency stop push button is located on the front of the junction box door. The push button is red with a round shape. When this push button is depressed, the switch is in the OFF position which shuts down the engine. The push button will remain depressed until the push button is manually released to the ON position. The engine cannot be restarted if the push button is depressed.

When the push button on the switch is depressed, the following events occur in the circuit in order to stop the engine.

1. An open circuit is made across contacts (ES-1A) and (ES-2A) (line 9).

2. The slave relays (SR1) and (SR2) are de-energized.

3. When the current stops, (SR1) is de-energized. The contacts (SR1-30) and (SR1-87) (line 43) open.

4. When (SR1) is de-energized, the fuel solenoid (FS) is also de-energized and the fuel flow to the engine stops.

Show/hide table

Accidental engine starting can cause injury or death to personnel working on the equipment. To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system. Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.

In order to start the engine again, perform the following procedures.

1. Correct any faults that might cause the emergency shutdown.

2. Manually reset the air shutoff lever which is located at the top of the air inlet housing.

3. Make sure that the push button of the emergency stop switch has been reset on the junction box of the engine. Turn the push button in the direction that is shown on the face of the push button in order to reset the button. The push button moves outward in order to reset.

4. Move and hold the toggle of the start/stop switch in the START position in order to restart the engine. If the engine is equipped with an engine mounted start switch, the lever of the switch must be in the START position in order to restart the engine.

Fault Circuit Operation

Oil Pressure Fault (OPS1)

When the engine begins to run the oil pressure will build up to a sufficient operating range. The circuit closes across the contacts (OPS1-1) and (OPS1-2) of the oil pressure switch (OPS1) (line 13).

The process of arming the electric protection system is described in the "Engine Operation" section.

The following events in the electrical circuit occur if the engine loses oil pressure.

1. The oil pressure switch (OPS1) opens across contacts (OPS1-1) and (OPS1-3) (line 24).

2. The current flow through diodes (D1) and (D2) is stopped. This de-energizes the slave relay (SR1) (line 28).

3. An alternate current path through contacts (SR2-30) and (SR2-87) (line 27) allows the (SR2) (line 25) to remain energized.

4. Diode (D1) (line 24) will not allow the current to flow through diode (D2 (line 27) in order to energize relay (SR1).

5. (SR1) remains de-energized and the contacts across (SR1-30) and (SR1-87) (line 30) remain open.

6. When the fuel solenoid (FS) is de-energized, fuel flow to the engine is stopped. This causes engine shutdown.

The slave relay (SR2) will remain energized, even after the engine has completely stopped. The relay is energized until the start/stop switch (SSS) is moved to the STOP position or until the emergency stop push button is depressed.

Show/hide table

Accidental engine starting can cause injury or death to personnel working on the equipment. To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system. Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.

Water Temperature Fault (WT)

The current flow for the circuit that is described in this section is applicable for all engines. The engine must be running at a speed with a coolant temperature that is hot enough to close the water temperature contactor switch (WTS). The water temperature contactor switch is normally open. The following events occur in the electric circuit in order to shut down the engine. The engine will shut down when the temperature of the coolant system is greater than the maximum temperature that is set for the WTS.

1. The water temperature contactor switch (WTS) closes across the contacts , which are normally open.

2. Closing the contacts (WTS-1) and (WTS-2) opens the circuit to slave relay (SR1) (line 33).

3. When the open circuit de-energizes (SR1) and (SR2), the circuit opens across the relay contacts (SR1-30) and (SR1-87) (line 43).

4. The open circuit de-energizes the fuel solenoid (FS) which shuts off the fuel flow to the engine.

The starter motor circuit can then be engaged. However, there is no fuel flow to the engine and the engine cannot be restarted until the coolant temperature falls below the rating of the water temperature contactor switch. When the water temperature is below the maximum rating for the temperature of the WTS, the circuit opens across contacts (WTS-1) and (WTS-2). The slave relay (SR1) and the fuel solenoid (FS) can then be energized by the engine starting circuit in order to restart the engine.

Show/hide table

Accidental engine starting can cause injury or death to personnel working on the equipment. To avoid accidental engine starting, disconnect the battery cable from the negative (−) battery terminal. Completely tape all metal surfaces of the disconnected battery cable end in order to prevent contact with other metal surfaces which could activate the engine electrical system. Place a Do Not Operate tag at the Start/Stop switch location to inform personnel that the equipment is being worked on.

2301A Electric Governor Control

The 2301A Electric Governor Control activates all of the components that are in the electric protection system. The components are activated in the same manner when the nonelectric governor is used. One difference exists in the main circuit. The fuel shutoff solenoid (FSOS) (line 43) is not used.

When the electric governor control is used, the engine must run in a normal condition in order for the electric circuit to operate in the manner that is described below.

1. Current flows from the terminals (TS-28) (line 30) and (TS-31) (line 31), which are located on the terminal strip in the junction box.

2. Current from terminals (TS-28) (line 32) and (TS-31) (line 33) flows through the preregulator (PR) (line 37) or the fuse (F4) to the electric governor control.

3. When the engine flywheel is rotating, the current also flows through the electric governor actuator (EGA) (line 34).

When a fault in the system causes the current to energize the slave relay (SR1), the following events occur in the electric circuit in order to stop the engine.

1. The slave relay (SR1) opens across the contacts (SR1-30) and (SR1-87a) (line 32). The relay closes across the contacts (SR1-30) and (SR1-87) (line 30).

2. When the circuit opens across contacts (SR1-30) and (SR1-87a), the current is stopped to the electric governor control.

3. Current to the electric governor actuator (EGA) is also stopped.

4. The mechanical spring load in the electric governor actuator (EGA) will now move the fuel control rod in order to stop fuel flow to the engine.

Note: With the exception of the differences that are described in this section of the manual, all of the fault circuits in the electric protection system are identical for the 2301A Electric Governor Control and for the nonelectric governor control.

Illustration 4	g00292646
Junction Box Wiring for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3200 through 3400 Engines

Illustration 5	g00292649
JIC Schematic for ETR protection system with OP and WT that does not require a switchgear for use on 3200 through 3400 Engines

Illustration 6	g00292651
IEC Schematic for ETR protection system with OP and WT that does not require a switchgear for use on 3200 through 3400 Engines

Illustration 7	g00292652
2W-8908 Wiring Harness for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3200 through 3400 Engines

Illustration 8	g00292481
IEC and JIC Schematics of dual starting motors (if equipped)

Illustration 9	g00292482
IEC and JIC Schematics for a prelube pump (if equipped)