ELECTRONIC MODULAR CONTROL PANEL (SR-4 GENERATOR MOUNTED) Caterpillar

Control Panel
(1) ACM (AC meter module). (2) ALM (alarm module) optional. (3) ECM (engine control module). (4) VAR (voltage adjust rheostat). (5) Switch (display hold switch). (6) PLS (panel light switch) optional. (7) ESPB (emergency stop push button) optional. (8) ECS (engine control switch). (9) SP (speed adjust potentiometer) or GS (governor switch) optional. (10) AVS (ammeter-voltmeter phase selector switch). (11) LTS (lamp/display test switch). (12) ALS (alarm silence push button).

NOTE: For point to point wiring diagrams and schematics, make reference to that section located in the back of the book.

Location And Function Of Controls

The center of the panel may be a plain cover or one of the alarm modules (2). These optional alarm modules will be described later.

AC Meter Module (ACM) (Make Reference To The AC Schematic)

The left part of the control panel contains the AC meter module (ACM) (1). This module has digital liquid crystal displays for AC volts - V, frequency - Hz, and AC amps - A. These displays indicate the status of the generator output. The ammeter-voltmeter switch (AVS) (10) near the center of the panel is used to select the phase being displayed by the volts and amps display.

Show/hide table

To avoid personal injury due to electrical shock, make sure jumpers are installed correctly on the AVS.

Each of the AVS three positions 1, 2 and 3 allows the operator to check generator output current and voltage for each of the phases 1, 2 and 3 respectively.

If the voltage or current exceeds the programmed maximum, the display will flash the full scale value. Voltage below 1 VAC and currents below .1% of full scale will be displayed as 0.

The frequency display (Hz) shows the frequency in hertz (cycles per second) of the electricity made when the generator set is in operation. There is a direct relation between the frequency of the electricity and the rpm of the generator set, as shown in following formula:

For frequencies above 99.9 Hz, the display will flash "99.9". Frequencies below 45 Hz will be displayed as "LO".

Procedure C on programming the ACM gives details on the full scale currents and voltages that can be programmed into the ACM. If the ACM shows all dashes, the ACM has an internal fault and must be replaced.

Control Panel Face

The control switches are located below AC meter module (1). Near the lower left corner of the panel is the optional red emergency stop push button (ESPB) (7). When this button is pressed, the fuel is shut off and the optional air shutoff is activated. To restart, this push button must be turned until it pops out. To the right of the emergency stop is the engine control switch (ECS) (8).

The ECS determines the status of the control panel. In the automatic position (3 o'clock), the engine will start automatically whenever the remote initiating contact (IC) (line 47) is closed. The engine will also shut down after the initiate contacts open. An adjustable cooldown time can be programmed to give a 0 to 30 minute cooldown period before the engine shuts down. In the manual (run) position (6 o'clock), the engine will start and run as long as the ECS is in this position. In the stop position (9 o'clock), the fuel solenoid shuts the engine down after cooldown. In the off/reset position (12 o'clock), the fault lights are reset and engine shuts down immediately. If the jumper (line 38) (see note F on DC schematic) is removed, the power to the ECM will be disconnected 70 seconds after shutdown on energized to shutdown (ETS) systems and immediately on energized to run (ETR) systems.

In the center of the control panel, there is the lamp/display test switch (LTS) (11). When it is in the test position, all lamps and display segments (segments will read 8888888) in ECM (3), ACM (1) and the optional alarm module (2) will be lighted. The alarm horn in the ALM (2) will also sound for ten seconds maximum.

Near the left of the control panel, is the voltage adjust rheostat (VAR) (4). This rheostat is used to adjust generator voltage to the desired level. To the right of voltage adjust rheostat (VAR) (4) is the optional governor switch (GS) (9). This switch is used to raise and lower engine speed when the governor used has a speed adjust motor. If 2301 Governor or other electronic governor is used, a speed adjust potentiometer (SP) is mounted in this location.

Engine Control Module (ECM)

The right side of the control panel contains the engine control module (ECM) (3). This is the "brain" of the system and also displays fault conditions and key engine parameters.

The engine control module (ECM) (3) accepts information from the operator, magnetic speed pickup (MSP) (line 21), oil pressure (OP) and water temperature (WT) transducer (line 49), and optional (line 18, 19) remote sources. This information is used to determine the "on/off" state of the engine's air, fuel and starter.

Engine Control Module
(5) Switch (display hold switch). (13) Display LCD. (14) Overcrank LED. (15) Low oil pressure LED. (16) Overspeed LED. (17) Emergency stop LED. (18) Overtemperature LED. (19) Reverse power LED.

In the very basic operating conditions, the ECM receives a signal to run the generator set. The ECM then turns on the engine's fuel and starter. When the engine speed reaches the crank termination speed, the starter is disengaged. When the ECM receives a signal to stop the engine, it shuts the fuel off.

The ECM has the following features:

Cycle Crank - The ECM can be programmed to crank-rest-crank etc. for adjustable time periods (see Service Procedure A for adjusting).

2301 Control - When the engine oil pressure increases past the low oil pressure setpoint, the ECM will indicate to a 2301 Woodward Governor that it should increase the engine speed from idle to rated.

Cool Down - Upon receiving a signal to perform a normal shutdown, the ECM will wait a preprogrammed amount of time before shutting the engine off by means of the fuel control.

Automatic Operation - While in the automatic mode, the ECM can be started by a remote initiate signal [when initiate contact (IC) (line 47) closes]. Upon loss of the signal, the ECM will perform a normal shutdown.

Alarm Module Communication - The ECM can transmit fault and alarm conditions to an alarm module.

Power Down - The electronic modular control panel (EMCP) system is designed to remove power from the ECM when in the off/reset mode. The ECM will not allow the power down until the crank termination relay and the fuel control relay are both "off" for about 70 seconds.

Fuel Solenoid Type - The ECM can be programmed to work with either an energize to run (ETR) fuel system or an energize to shutdown (ETS) and latching fuel system.

LED Display - Six LEDs are located on front of the ECM to annunciate overcrank shutdown, overspeed shutdown, low oil pressure shutdown, high coolant temperature shutdown, emergency stop and reverse power shutdown. The reverse power LED can be used as a spare fault indication when the reverse power relay option is not used.

Emergency Stop - If the ECM detects an emergency stop, the engine will shut down by means of the air and fuel control. LED (17) will flash.

Transducer Module Malfunction - If the signal from the engine mounted oil pressure/temperature transducer module is lost or unreadable, the engine will be shut down by means of the fuel control and a diagnostic code will be displayed. The ECM can be programmed to ignore the transducer module malfunction.

Speed Pickup Malfunction - If the ECM loses its magnetic pickup signal, the engine will be shut down by means of the air and fuel control. A diagnostic code will be displayed by the ECM.

Overcrank Protection - If the engine fails to start in a preprogrammed amount of time, the ECM will halt the starting sequence and flash an LED (14). Another attempt at starting the engine cannot be made without first going into the off/reset position on the ECS.

Liquid Crystal Display (13) - Service hours, engine speed, system battery voltage, engine oil pressure and engine coolant temperature are displayed in sequence in either English or metric units. Pressing switch (5) on the front of the ECM will cause the display to lock (stop) on one of the engine parameters. Pressing the switch again will resume the display to normal sequencing. The display is also used to indicate diagnostic codes, to aid in troubleshooting. See Troubleshooting, Using Diagnostic Code Interpretation.

Lamp Test - When the ECM detects a lamp test, it will turn "on" all the LCD segments and LEDs. If the lamp test signal lasts for more than 10 seconds, the ECM will go out of its lamp test mode and return to normal operation.

Overspeed Protection - If the engine speed exceeds the overspeed setpoint, it will be shut down by means of the air (if equipped) and fuel control. LED (16) will flash. The overspeed setpoint is lowered to 75% of its original value while the overspeed verify switch is depressed. This will allow the overspeed circuit to be tested while a generator set is operating at rated speed. See illustration in Location of Components showing location of this switch on back of ECM.

Low Oil Pressure Protection - If the engine oil pressure drops below the low oil pressure setpoint, it will be shut down by means of the fuel control. LED (15) will flash. There are two low oil pressure setpoints. One when the engine speed is below the oil step speed. The setpoint is for other setpoint in for when the engine speed is above the oil step speed.

High Coolant Temperature Protection - If the engine coolant temperature exceeds the high coolant temperature setpoint, the engine will shut down by means of the fuel control. LED (18) will flash.

ECM Sequence Of Operation (Normal Start-Stop)

Upon receipt of a signal to start, the ECM will check to assure that:

a. An emergency stop signal is not present.

b. All faults have been reset.

c. All sensors are connected and operating properly.

d. No abnormal engine control switch signals are present.

e. The engine is not already running.

f. The ECM microprocessor is functioning properly.

g. The ECM is not in the programming mode.

The ECM will not allow the start sequence to begin and will display the proper diagnostic code when applicable, if an above fault condition exists. However, once the ECM is satisfied that conditions are normal, it will energize the starting motor relay (SMR) and run relay (RR).

If the generator set is a latching type when the starting motor magnetic switch (SMMS) is energized the latching fuel control solenoid (LFS) is also energized to turn the fuel on. This momentary current flow through a special latch mechanism on the solenoid holds the solenoid in the on position.

If the generator set fuel system is an energized to run (ETR) type, the ECM will also signal for fuel (or the electronic governor) to be turned on by energizing the fuel control relay (FCR).

If the cycle crank feature is enabled, the ECM will automatically crank-rest-crank the engine for adjustable time periods. If the generator set fails to start within the selected total crank time, the ECM will execute an overcrank fault. If a fault condition occurs while the engine is cranking, the ECM will terminate and lock out cranking. The ECM will display the applicable diagnostic code or light the appropriate LED.

After the engine starts and has achieved the proper crank termination speed, the ECM will de-energize the starting motor by de-energizing SMR and will energize the crank termination relay (CTR). Once safe low idle oil pressure is achieved, the ECM will signal for the optional 2301 governor to accelerate the generator set to rated speed, by energizing the 2301 relay.

The generator set will run as long as operating conditions remain normal and a signal to run is being received by the ECM. The ECM will display in sequence (each for a two second period) the engine lube oil pressure, water temperature, RPM, service hours, and system DC volts; by means of the digital display prior to or while the engine is operating. At the same time, the ECM will monitor for any fault or abnormal conditions that may occur.

Upon loss of the run signal, the engine will continue to run for an adjustable cooldown period if the cooldown feature is utilized. However, if the cooldown feature is not used or if the ECM receives an off/reset signal, it will immediately de-energize the run relay. If the fuel system is an energize to shutdown (ETS) or latching type, the fuel circuit will be energized at this point. The fuel circuitry will be de-energized for energized to run (ETR) type (or 2301) systems. If the signal to run returns before the engine stops, the ECM will immediately go back to the running state, i.e., fuel will be turned back on for the ETR and ETS systems. The latching fuel system will not be turned on because the starting motor did not energize. However, if restart does not occur and RPM continues to drop, the ECM will initiate cranking upon reaching zero RPM. Assuming that the run signal does not return and the engine speed continues to diminish until zero RPM is reached, the crank termination relay (CTR) will be de-energized and the ECM will be ready for an instant restart. The fuel control relay will be ready for an instant restart. The fuel control relay (FCR) of the ECM will de-energize 70 ± 10 seconds after zero RPM is reached, for engines with energized to shutdown and latching fuel systems, or immediately upon receiving a signal to run.

ECM Sequence Of Operation (Fault Conditions)

If a fault condition occurs prior to starting the generator set, the ECM will:

a. De-energized and lock out the starting motor circuit.

b. Assure that fuel is shut off.

c. De-energize the run relay circuit.

d. Energize the fault shutdown circuitry, engine failure relay (ENFR).

If a fault condition occurs while the generator set is running, the ECM will respond as follows:

e. Fuel control circuitry will be:

- De-energized for energized to run engines.

- Energized for energized to shutdown and latching engines, and then de-energized 70 ± 10 seconds after the engine reaches zero RPM.

f. Air shutoff relay (ASR) will be energized, for an overspeed, emergency stop, or diagnostic codes 01, 04, 06 or if all six LED's are on. The ASR will also energize if the engine has not shutdown within 10 seconds after the FCR commanded it to do so as a result of a fault condition. The ASR circuitry shall be de-energized 15 to 20 seconds after the engine reaches zero rpm.

g. The starter motor relay (SMR) circuitry shall be locked in the de-energized state.

h. The run relay (RR) circuity shall be de-energized.

i. The fault shutdown circuity shall be energized, engine failure relay (ENFR).

If a fault occurs before or after the engine starts, the appropriate fault indicating LED shall flash a 2 Hz or a diagnostic code shall be displayed to indicate the nature of the problem. The indicators shall remain on and the ECM shall remain in the fault mode until it receives a reset signal.

Control Panel Sequence Of Operation

NOTE: Jumper wire between engine control switch (ECS) terminals 9 and 6 may be removed if it is desirable to turn off the ECM and ALM by means of the ECS "OFF" position. The jumper should be removed in order to limit battery drain.

Normal Start-Stop Sequence

The engine control switch (ECS) of the control panel has four positions - "AUTO, RUN (MANUAL), COOL DOWN/STOP, OFF/RESET". If the ECS is in the "AUTO" position and a signal to run is received from a remote initiate contact (IC), or the ECS is placed in the "RUN" position, the generator set will crank, terminate cranking and run. The generator set may cycle crank if the cycle crank feature is utilized. Generator sets equipped with electronic governors will run at low idle speed until lube oil pressure has exceeded the idle low oil pressure setpoint. Then the 2301 relay contact of the ECM will close and the engine will accelerate to rated speed. Generator sets with hydra-mechanical govenors will accelerate to their speed setting immediately after crank termination. Once the generator is running, the ACM will display amps, volts and frequency, and the operator may make voltage and frequency adjustment. The generator set will run until the signal to run is removed by either turning the engine control switch to "COOL DOWN/STOP", "OFF", or the remote initiate contact opens. Once the engine control switch is moved to the "OFF" position, the generator set will shut down immediately. However, if the control switch is placed in the "COOL DOWN/STOP" position, or if in the "AUTO" position and the remote initiate contact opens, the generator set will run for a short time in the cooldown mode, if the cooldown feature was utilized. Otherwise, the generator set will shutdown immediately. The generator set shall then be capable of immediate restart.

During a normal start, run, stop sequence of operation and prior to cranking, all displays are activated.

NOTE: The AC metering display is not activated unless the ECMP has a signal to run.

After crank termination, the governor raise-lower switch (GS) circuit shall be deactivated, to allow governor speed setting changes only while the generator set is running. The auxilliary relay will be energized to switch on customer high power loads such as exhaust fans.