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

Illustration 1	g00569647
ETR Junction Box with oil pressure protection (OP), water temperature protection (WT), and overspeed protection (OS) that does not require a switchgear for use on 3200 through 3400 Engines (1) Terminal strips (TS) (2) Wiring harness (3) Electronic speed switch (ESS) (4) Junction box (5) Identification foil (6) Jumper between terminals (TS-3) and (TS-4) (7) Diodes (D3) and (D4) (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) Circuit breakers (16) Engine oil pressure switch (OPS1) (17) Mounting brackets for grommets

Illustration 2	g00290419
ETR Junction Box with oil pressure protection (OP), water temperature protection (WT), and overspeed protection (OS) that does not require a switchgear for use on 3500 Engines (1) Terminal strips (TS) (2) Wiring harness (3) Electronic speed switch (ESS) (4) Junction box (5) Identification foil (6) Jumper between terminals (TS-3) and (TS-4) (7) Diodes (D3) and (D4) (8) Emergency stop switch (ES) (9) Jumper between terminals (TS-27) and (TS-28) (10) Jumper between terminals (TS-28) and (TS-29) (11) Jumper between terminals (TS-30) and (TS-31) (12) Diode for electric governor actuator (if equipped) (13) Slave relay (SR1) (14) Slave relay (SR2) for air shutoff solenoid (ASOS) (15) Slave relay (SR3) for starting aid switch (if equipped) (16) Grommets for engine oil pressure switches (17) Start/stop switch (SSS) (18) Circuit breakers (19) Engine oil pressure switch (OPS1) (20) Mounting brackets for grommets (21) Engine oil pressure switch (OPS2) (if equipped)

Introduction

The ETR Junction Box with oil pressure protection (OP), water temperature protection (WT), and overspeed protection (OS) 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:

• Engine overspeed

• Crank termination

• Oil pressure

• Coolant temperature

The junction box includes the following components:

• Electronic speed switch (ESS) (3)

• Start/stop switch (SSS) (17) and (14)

• Slave relay (SR1) (11) and (13)

• Slave relay (SR2) (if equipped) with an air shutoff solenoid (ASOS) (12) and (14)

• Oil pressure switch (OPS1) (16) and (19)

• Oil pressure switch (OPS2) that is only in 3500 Engines (21)

• 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)

• Air shutoff solenoid (ASOS)

• Water temperature switch (WTS)

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

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 always available across the terminals (ESS-5) and (ESS-6) (line 54) of the electronic speed switch (ESS). All of the switches are in the normally open position or the normally closed positions at that time.

Engine Start-up

Illustration 3	g00282721
2W-6832 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. Current can then flow through diode (D3) (line 18) and through the water temperature contactor switch (WTS), which is normally open.

5. The SSS closes in order to energize slave relay (SR1) (line 36).

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

7. 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 Switch (EMSS)

Illustration 4	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 starts to run and the speed setting of the crank termination is reached, the crank terminate switch stops the current to the starter motor circuit. The starter motor will stop even if the start/stop switch (SSS) is held in the START position. The crank terminate switch is located in the electronic speed switch. When crank termination is reached, the following events occur in the electric circuit.

1. The contacts for the crank terminate switch (CT) (line 17) open across terminals (ESS-11) and (ESS-12) (line 9). The contacts across terminals (ESS-10) and (ESS-11) (line 13) close.

2. The current then flows through diode (D2) and the overspeed switch (OSS) contacts (ESS-8) and (ESS-9) (line 29).

3. The current continues through the WTS (line 18) to the SSS (line 24).

4. If the SSS is still in the START position, a current should flow across contacts of the SSS to the slave relay (SR1) (line 36). The current will keep the slave relay and the fuel solenoid energized.

5. When the SSS is released from the START position, the switch should be manually moved to the RUN position. The switch may automatically return to the RUN position.

6. The current flows across contacts (OPS1-1) and (OPS1-2) (line 13) of the oil pressure switch (OPS1). The contacts are closed.

7. The current flows across contacts (ESS-14) and (ESS-15) of the oil pressure step switch (OPSS) (3500 Engines).

8. The current flows to (SR1) (line 36) which keeps the relay energized.

If the engine oil pressure switch (OPS1) has not closed across contacts (OPS1-1) and (OPS1-2) before the SSS is released to the RUN position, (SR1) will de-energize. When (SR1) is de-energized, the fuel solenoid is also de-energized. The fuel solenoid shuts off the fuel flow to the engine. (OPS1) will not close across contacts (OPS1-1) and (OPS1-2) if insufficient oil pressure exists.

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 push button of the emergency stop switch is located on the front of the junction box door. The push button is red and the push button has 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.

The following events occur in the circuit to the fuel solenoid (FS) (line 43) when the push button is depressed.

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

2. An open circuit is also made across contacts (ES-1B) and (ES-2B) (line 18) which stops current to the slave relay (SR1).

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.

When the emergency stop push button is depressed, the air shutoff solenoid (ASOS) (line 48) is energized and the inlet air to the engine is shut off. The following events occur in the electric circuit in order to stop the engine.

1. A closed circuit is made across the contacts (ES-3A) and (ES-4A) (line 33) which energizes the slave relays (SR1) (line 34) and (SR2) (line 33).

2. When (SR2) is energized, and if (SR2) is equipped with an air shutoff solenoid, the circuit closes across the contacts (SR2-30) and (SR2-87) (line 48) in order to energize the air shutoff solenoid (ASOS).

3. When the engine stops, the crank terminate switch (CT) (line 17) opens across contacts (ESS-11) and (ESS-12).

4. The open circuit across contacts (ESS-11) and (ESS-12) cause the slave relay (SR2) (line 33) to become de-energized. This causes the contacts of the slave relay (SR2) (line 48) to return to the normally open position.

5. The open position of the (SR2) contacts de-energizes the air shutoff solenoid (ASOS) (line 48).

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 following events will then occur in the electric circuit.

1. The circuit closes across the contacts (OPS1-1) and (OPS1-2) of the oil pressure switch (OPS1) (line 13).

2. The current then flows to the crank terminate switch (CT) (line 17). The switch is closed across contacts (ESS-10) and (ESS-11).

3. The current flows through the overspeed switch (OSS) (line 29) which is open across contacts (ESS-8) and (ESS-9).

4. The current flows through the water temperature switch (WTS) (line 18) which is open across contacts (WTS-1) and (WTS-2).

5. The current flows through the start/stop switch (SSS) (line 24) which is in the RUN position.

6. The current flows through oil pressure switch (OPS1) which is closed across contacts (OPS1-1) and (OPS2-2).

7. When the engine runs at a speed below the oil step speed setting, the current also flows through the oil pressure step switch (OPSS) (line 13). This only occurs on 3500 Engines.

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 (OPS1-2) (line 13). The switch closes across contacts (OPS1-1) and (OPS1-3).

2. When the switch on 3500 Engines closes across contacts (OPS1-1) and (OPS1-3) (line 13) , the oil step latch of electronic speed switch (ESS-17) is energized. The oil step latch is a feature that will hold the CT switch (line 17) in a closed position across contacts (ESS-10) and (ESS-11). The switch will remain in that position until two seconds after the engine rotation has stopped.

3. (OPS1) makes an open circuit which de-energizes relay (SR1).

4. The contacts across (SR1-30) and (SR1-87)of the slave relay (line 43) open and the fuel solenoid (FS) is de-energized.

5. When the FS is de-energized, the fuel flow to the engine is stopped. This causes engine shutdown.

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.

After the CT switch opens across contacts (ESS-11) and (ESS-12) and the switch closes across contacts (ESS-11) and (ESS-10), the engine can be restarted immediately.

Oil Pressure Fault (OPS2) (3500 Engines)

A fault occurs in the high pressure side of the oil pressure circuit when the engine is running at a speed above the oil step speed setting. The oil pressure must also be at least equal to the oil step speed setting. When the engine is running at a speed that is above the oil step speed setting, the electric current will follow the same path that is described in the "Oil Pressure Fault (OPS1)" section of this manual. There is a few exceptions that are listed below.

1. The oil pressure step switch (OPSS) is closed across contacts (ESS-14) and (ESS-13) (line 13).

2. The oil pressure switch (OPS2) is closed across contacts (OPS2-1) and (OPS2-2).

3. The switch (OPSS) is already closed because the engine has been running at a speed above the step oil pressure setting.

4. The current flows through the two oil pressure switches (OPS1) and (OPS2).

5. The current flows through diode (D4) which then energizes slave relay (SR1) across contacts (SR1-85) and (SR1-86). The circuit through (OPS1) is no longer energizing (SR1).

A fault exists when the engine oil pressure decreases below the higher pressure setting of (OPS2). When a fault occurs, the following events occur in the electrical circuit in order to stop the engine.

1. The oil pressure switch (OPS2) opens across contacts (OPS2-1) and (OPS2-2) (line 13) and the switch closes across contacts (OPS2-1) and (OPS2-3).

2. Slave relay (SR1) (line 36) is de-energized across contacts (SR1-85) and (SR1-86).

3. (SR1) opens across contacts (SR1-30) and (SR1-87) (line 43) which de-energizes the fuel solenoid (FS).

4. When the fuel solenoid is de-energized, the fuel flow to the engine is stopped and the engine shuts down.

When the oil pressure switch closes across contacts (OPS2-1) and (OPS2-3) (line 13), the terminal (ESS-17) for the oil step latch on the electronic speed switch is energized. The oil step latch holds the CT switch (line 17) in a closed position across contacts (ESS-11) and (ESS-10). The switch will remain closed until 2 seconds after the engine rotation has completely stopped. This action prevents possible damage to the starter motor pinion and flywheel ring gear that is caused by the attempt to restart the engine before the engine has completely stopped.

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.

When the CT switch opens across contacts (ESS-11) and (ESS-12) and the switch closes across contacts (ESS-10) and (ESS-11), the engine can be restarted immediately.

Engine Overspeed

When the engine speed increases above the overspeed setting of the electronic speed switch (ESS) the following events occur in the electrical circuit in order to stop the engine.

1. The overspeed switch (OSS) closes across contacts (ESS-8) and (ESS-7) (line 29).

2. The slave relay (SR2) is energized and the contacts across (SR2-30) and (SR2-87) (line 48) are closed.

3. (SR2) energizes the air shutoff solenoid (ASOS) which stops the flow of inlet air to the engine.

4. The CT switch also opens across contacts (ESS-11) and (ESS-10) (line 17) and the slave relay (SR1) is de-energized .

5. Relay (SR1) opens across contacts (SR1-30) and (SR1-87) (line 43) which de-energizes the fuel solenoid (FS) and stops fuel flow to 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.

A reset button on the electronic speed switch must be pushed manually in order to open the overspeed switch (OSS) again. The air shutoff lever which is located on the top of the air inlet housing must also be manually reset to the open position before the engine can be restarted.

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), 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 43) and (TS-31) (line 44), which are located on the terminal strip in the junction box.

2. Current from terminals (TS-28) (line 43) and (TS-31) (line 44) flows through the preregulator (PR) (line 48) 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 52).

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 45). The relay closes across the contacts (SR1-30) and (SR1-87) (line 43).

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 5	g00292615
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 6	g00292616
JIC Schematic for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3200 through 3400 Engines

Illustration 7	g00292617
IEC Schematic for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3200 through 3400 Engines

Illustration 8	g00292470
6I-1842 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 9	g00292618
Junction Box Wiring for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3500 Engines

Illustration 10	g00292620
JIC Schematic for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3500 Engines

Illustration 11	g00292622
IEC Schematic for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3500 Engines

Illustration 12	g00292472
100-3639 Wiring Harness for ETR protection system with OP, WT, and OS that does not require a switchgear for use on 3500 Engines

Illustration 13	g00292481
IEC and JIC Schematics of dual starting motors (if equipped)

Illustration 14	g00292482
IEC and JIC Schematics for a prelube pump (if equipped)