CONTROL PANEL SR4 GENERATOR MOUNTED Caterpillar


Latching Fuel Solenoid System

Usage:



ECS In AUTO Position

IC Closed


Simplified schematic

When engine control switch (ECS) is in the auto position, ECS contacts (9 and 10) (lines 56 and 57) are also closed. When initiating contact (IC) (line 59) is closed, the run relay (RR) (line 56) energizes. This causes RR contacts (8 and 5) (line 14), RR (6 and 9) (line 17) and RR (7 and 4) (line 20) to close.

RR (8 and 5) (line 14) - Normally open (N.O.) contact across RR (8 and 5) closes to energize the slave relay #1 (SR1) (line 14). SR1 contacts (line 13) open.

RR (6 and 9) (line 17) - Normally open (N.O.) contact across RR (6 and 9) closes to energize the starting motor magnetic switch (SMMS1) (line 17). When SMMS1 closes its contact (line 6) current is sent in two directions. Current actuates the solenoid (LFS) (line 7) which is then mechanically latched in the fuel ON position. Current also energizes pinion solenoid #1 (PS1) (line 6) which in turn closes its contact (line 5) to energize the starting motor #1 (SM1) (line 5). Also, the overcrank timer (OCT) (line 21) starts its timer. After the engine cranks for approximately 30 seconds without the engine starting, OCT will energize the overcrank fault relay (OCR) (line 35).

RR (7 and 4) (line 20) - Normally open (N.O.) contact across RR (7 and 4) closes. This connects the engine speed switch (terminal 10) to the arming delay timer (ADT) (terminal 1). When the engine reaches 400 rpm the ADT will energize.

Once the engine has started and reached approximately 400 rpm:

The engine speed switch's (ESS) crank termination (CT) (contacts 11 and 10) (line 20) close. This energizes the ADT (line 20) which has a 10 second delay. The delay allows time for initial oil pressure to build-up causing the oil pressure switch (OPS) (line 39) to open at 93.0 ± 21 kPa (13.5 ± 3.5 psi). This prevents the oil pressure fault relay (OPR) (line 39) and light (OPL) (line 40) from energizing on normal start-up and shutdown.

As the engine starts and ESS senses a speed of 400 rpm through the magnetic speed pickup (MPU) (line 62), the ESS opens the starting motor and latching fuel solenoid circuit by opening the crank termination switch contact across ESS (CT) (11 and 12) (line 17).


Simplified Schematic

When engine control switch (ECS) is in the auto position, ECS contacts (5 and 6) (line 36) are also closed. This provides a path to latch in one of the fault relays (OCR, OPR, WTR or OSR) should a fault occur.

IC Open

If the engine is running with the ECS in the auto position, ECS contacts (9 and 10) (lines 56 and 57) and initiating contact (IC) (line 59) are closed. When the IC opens, run relay (RR) (line 56) de-energizes. This opens RR contacts (8 and 5) (line 14) which stops current from flowing to the slave relay (SR1). When SR1 is de-energized, its contacts (line 13) close allowing current to flow to the latching fuel solenoid (LFS) (line 13). When energized, the LFS unlatches from the fuel ON position and mechanically latches to the fuel off position.

ECS In Manual Position


Simplified schematic

When engine control switch (ECS) in the MANUAL position, ECS contacts (9 and 11) (line 56) close. Run relay (RR) (line 56) energizes which causes RR contacts (8 and 5) (line 14), RR (6 and 9) (line 17) and RR (7 and 4) (line 20) to close.

RR (8 and 5) (line 14) - Normally open (N.O.) contact across RR (8 and 5) closes to energize the slave relay #1 (SR1) (line 14). SR1 contacts (line 13) open.

RR (6 and 9) (line 17) - Normally open (N.O.) contact across RR (6 and 9) closes to energize the starting motor magnetic switch (SMMS1) (line 17). When SMMS1 closes its contact (line 6) current is sent in two directions. Current actuates the solenoid (LFS) (line 7) which is then mechanically latched in the fuel ON position. Current also energizes pinion solenoid #1 (PS1) (line 6) which in turn closes its contact (line 5) to energize the starting motor #1 (SM1) (line 5). Also, the overcrank timer (OCT) (line 21) starts its timer. After the engine cranks for approximately 30 seconds without the engine starting, OCT will energize the overcrank fault relay (OCR) (line 35).

RR (7 and 4) (line 20) - Normally open (N.O.) contact across RR (7 and 4) closes. This connects the engine speed switch (terminal 10) to the arming delay timer (ADT) (terminal 1). When the engine reaches 400 rpm the ADT will energize.

Once the engine has started and reached approximately 400 rpm:

The engine speed switch's (ESS) crank termination (CT) (contacts 11 and 10) (line 20) close. This energizes the ADT (line 20) which has a 10 second delay. The delay allows time for initial oil pressure to build-up causing the oil pressure switch (OPS) (line 39) to open at 93.0 ± 21 kPa (13.5 ± 3.5 psi). This prevents the oil pressure fault relay (OPR) (line 39) and light (OPL) (line 40) from energizing on normal start-up and shutdown.

As the engine starts and ESS senses a speed of 400 rpm through the magnetic speed pickup (MPU) (line 62), the ESS opens the starting motor and latching fuel solenoid circuit by opening the crank termination switch contact across ESS (CT) (11 and 12) (line 17).

ECS In Stop Position

If the engine is running with the ECS in the MANUAL position, ECS contacts (9 and 11) (line 56) are closed. When the ECS is turned to the STOP position ECS contact 11 (line 56) opens and run relay (RR) (line 56) de-energizes. This opens RR contacts (8 and 5) (line 14) which stops current from flowing to the slave relay (SR1). When SR1 is de-energized, its contacts (line 13) close allowing current to flow to the latching fuel solenoid (LFS) (line 13). When energized, the LFS unlatches from the fuel ON position and mechanically latches to the fuel off position.

Current flow through ECS contacts 8 and 5 (line 36) provides a path to latch in one of the fault relays (OCR, OPR, WTR or OSR) should a fault occur.

ECS In Reset Position


Simplified schematic

In the RESET position, ECS contacts 6 and 5 (line 36), 7 and 8 (line 37), 9 and 11 (line 56) and contact 10 (line 57) are all open. In this position there is no current supplied to latch any of the fault relays (OCR, OPR, WTR or OSR).

Engine Shutdown Circuits

There are several ways an engine can be shutdown. The most common method is by turning the ECS to the STOP position. Further information on this method is covered under "ECS in stop position".

Engine Shutdown Caused By Oil Pressure Fault

At start-up, the run relay (RR) (line 56) is energized. This causes RR contacts (8 and 5) (line 14) for the slave relay (SR1), RR (6 and 9) (line 17) for the starting motor magnetic switch (SMMS1) and RR (7 and 4) (line 20) for the arming delay timer (ADT) to close. With the RR contacts (7 and 4) closed, the arming delay ADT (line 20) starts a 10 second delay before allowing the arming relay (AR) to energize and close across its contact AR (7 and 4) (line 39). Under normal conditions, the 10 second delay allows initial oil pressure to build-up to 93.0 ± 21 kPa (13.5 ± 3.5 psi) and open oil pressure switch (OPS) (line 39).


Simplified schematic

If initial oil pressure does not build-up in the 10 second time delay, OPS contacts (1 and 3) (line 39) will still be closed. AR contacts (7 and 4) (line 39) will now be closed to complete the circuit to the oil pressure fault relay (OPR) (line 39) and oil pressure light (OPL) (line 40). Relay OPR closes its contact (line 40) to latch in OPR. Relay OPR also closes its contact (line 52) to allow the engine failure relay (ENFR) (line 54) to energize. Normally closed (N.C.) contact ENFR (7 and 1) (line 56) opens to de-energize relay RR (line 56). The contact across RR (8 and 5) (line 14) opens to de-energize SR1. When SR1 is de-energized, its contacts (line 13) close allowing current to flow to the latching fuel solenoid (LFS) (line 13). When energized, the LFS unlatches from the fuel ON position and mechanically latches to the fuel OFF position. RR contacts (6 and 9) (line 17) open to prevent the starting motor magnetic (SMMS1) (line 17) from energizing. Relay RR (7 and 4) (line 20) opens which stops the flow of current to the arming relay (AR) (line 20).

The ENFR contacts (8 and 5) (line 60) also close and provide power to the optional shunt trip coil (SHTC) (line 60) of the generator output circuit breaker. This trips open the breaker.

------ WARNING! ------

To prevent personal injury due to accidental starting of the engine, disconnect the batteries before doing maintenance or repair work.

--------WARNING!------

To restart the engine, do the following steps:

1. Turn engine control switch (ECS) to STOP.

2. Correct the low oil pressure fault.

3. Rotate the ECS to RESET position which opens the circuit across ECS terminals (8 and 5) (line 36). This allows the OPR (line 39) to de-energize. OPR contact (line 40) opens and shuts off the light (OPL). Also, OPR contact (line 52) opens to de-energize the relay (ENFR). The contact across ENFR (7 and 1) (line 56) closes to allow restart.

4. The system is ready to start if ECS is turned to START or AUTO.

Engine Shutdown Caused By Water Temperature Fault


Simplified schematic

When the engine temperature becomes too high, the normally open water temperature switch WTS contacts (2 and 1) (line 43) close. This, in turn energizes the water temperature relay (WTR) (line 43) and water temperature fault light (WTL) (line 44). WTR contact (line 44) closes to latch in the relay WTR.

The normally open WTR contact (line 53) closes to energize the engine failure relay (ENFR) (line 54). Normally closed (N.C.) contact ENFR (7 and 1) (line 56) opens to de-energize relay RR (line 56). The contact across RR (8 and 5) (line 14) opens to de-energize SR1. When SR1 is de-energized, its contacts (line 13) close allowing current to flow to the latching fuel solenoid (LFS) (line 13). When energized, the LFS unlatches from the fuel ON position and mechanically latches to the fuel OFF position. RR contacts (6 and 9) (line 17) open to prevent the starting motor magnetic (SMMS1) (line 17) from energizing. RR contacts (7 and 4) (line 20) open which stops the flow of current to the arming relay (AR) (line 20).

------ WARNING! ------

To prevent personal injury due to accidental starting of the engine, disconnect the batteries before doing maintenance or repair work.

--------WARNING!------

To restart the engine, do the following steps:

1. Turn engine control switch (ECS) to STOP.

2. Correct the high water temperature problem. Allow the engine temperature to cool so WTS will reset.

3. Rotate the ECS to RESET position which opens the circuit across ECS terminals (8 and 5) (line 36). This allows the WTR (line 43) to de-energize. WTR contact (line 44) opens and shuts off the light (WTL). Also, WTR contact (line 53) opens to de-energize the relay (ENFR). The contact across ENFR (7 and 1) (line 56) closes to allow restart.

4. The system is ready to start if ECS is turned to START or AUTO.

Engine Shutdown Caused By Engine Overspeed


Simplified schematic

When engine speed increases above the overspeed setting (118% of rated speed) of the electronic speed switch, the overspeed switch contact ESS (OS) (line 47) will close across contacts (8 and 7). This, in turn energizes the overspeed relay (OSR) (line 47) and overspeed fault light (OSL) (line 48). OSR contact (line 48) closes to latch in the relay OSR.

The normally open OSR contact (line 54) closes to energize the engine failure relay (ENFR) (line 54). The contact across RR (8 and 5) (line 14) opens to de-energize SR1. When SR1 is de-energized, its contacts (line 13) close allowing current to flow to the latching fuel solenoid (LFS) (line 13). When energized, the LFS unlatches from the fuel ON position and mechanically latches to the fuel OFF position. RR contacts (6 and 9) (line 17) open to prevent the starting motor magnetic (SMMS1) (line 17) from energizing. RR contacts (7 and 4) (line 20) open which stops the flow of current to the arming relay (AR) (line 20).

------ WARNING! ------

To prevent personal injury due to accidental starting of the engine, disconnect the batteries before doing maintenance or repair work.

--------WARNING!------

To restart the engine, do the following steps:

1. Turn engine control switch (ECS) to STOP.

2. Correct the overspeed problem.

3. Rotate the ECS to RESET position which opens the circuit across ECS terminals (8 and 5) (line 36). This allows the OSR (line 47) to de-energize. OSR contact (line 48) opens and shuts off the light (OSL). Also, OSR contact (line 54) opens to de-energize the relay (ENFR). The contact across ENFR (7 and 1) (line 56) closes to allow restart.

4. The system is ready to start if ECS is turned to START or AUTO.

Engine Shutdown Caused By Emergency Stop Pushbutton

The emergency stop pushbutton (ESPB) is a red, mushroom shaped button which is located on the lower, right hand corner of the panel face. The ESPB shuts the engine down as follows:


Simplified schematic

When the ESPB is pushed in, ESPB contacts (2 and 1) (line 56) open to de-energize relay RR (line 56). The RR contacts (8 and 5) (line 14) open to de-energize SR1. When SR1 is de-energized, its contacts (line 13) close allowing current to flow to the latching fuel solenoid (LFS) (line 13). When energized, the LFS unlatches from the fuel ON position and mechanically latches to the fuel OFF position. RR contacts (6 and 9) (line 17) open to prevent the starting motor magnetic (SMMS1) (line 17) from energizing. RR contacts (7 and 4) (line 20) open which stops the flow of current to the arming relay (AR) (line 20). Also when the ESPB is pushed in ESPB contacts (3 and 4) (line 50) close and current is sent to the overspeed relay (OSR) (line 47) and overspeed fault light (OSL) (line 48). OSR contact (line 48) closes to latch in the OSR. The normally open OSR contact (line 54) closes to energize the engine failure relay (ENFR) (line 54). Normally closed (N.C.) contact ENFR (7 and 1) (line 56) opens.

------ WARNING! ------

To prevent personal injury due to accidental starting of the engine, disconnect the batteries before doing maintenance or repair work.

--------WARNING!------

To restart the engine, do the following steps:

1. Turn engine control switch (ECS) to STOP.

2. Correct any faults that may have been the cause of the emergency shutdown.

3. Make sure the red emergency stop button (ESPB) has been reset (button out). Turn the button the direction shown to reset.

4. Turn ECS to RESET position to clear the OSR and OSL.

5. Turn ECS to AUTO or START for start-up.

Engine Does Not Start (Overcrank Indicator Lights)


Simplified schematic

If the engine does not start in approximately 30 seconds overcrank timer (OCT) (line 21) will let current flow to the overcrank relay (OCR) (line 35) and overcrank light (OCL) (line 36). OCR will close its contact (line 36) to latch in the OCR. At the same time, OCR closes its contact (line 51) which allows the engine failure relay (ENFR) (line 54) to energize. ENFR opens its contact across ENFR (7 and 1) (line 56) which de-energizes the run relay (RR) (line 56). RR then opens its contact across RR (6 and 9) (line 17) which stops the flow of current to the starter motor magnetic switch (SMMS1) (line 17). When SMMS1 is de-energized, its contact (line 6) opens causing the starting motor to shutdown. The RR contacts (8 and 5) (line 14) open to de-energize SR1. When SR1 is de-energized, its contacts (line 13) close allowing current to flow to the latching fuel solenoid (LFS) (line 13). When energized, the LFS unlatches from the fuel ON position and mechanically latches to the fuel OFF position.

------ WARNING! ------

To prevent personal injury due to accidental starting of the engine, disconnect the batteries before doing maintenance or repair work.

--------WARNING!------

To start the engine, do the following steps:

1. Turn engine control switch (ECS) to STOP.

2. Correct the overcrank fault.

3. Turn the ECS to RESET position. This opens the circuit across ECS terminal 5 (line 36) and allows the OCR (line 35) to de-energize. OCR contact (line 40) opens and shuts off the light (OCL). Also, OCR contact (line 51) opens to de-energize the relay (ENFR). The contact across ENFR (7 and 1) (line 56) now closes to allow restart.

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