G3400 & G3500 GAS ENGINE DRIVEN CHILLER ENGINE CONTROL PANEL Caterpillar

Standard Chiller Operation

Description Of Engine Control Switches

Mounted on the inside of the engine control panel door is a group of switches which aid in the control of the engine. These switches should only be operated by a properly trained operator. The following is a brief description of the operation of each switch.

NOTE: Switches (1, 2, and 3) are a maintained-position type switch. Once a position is selected, the switch will remain there until manually changed.

Engine Control Switches
(1) Engine Control Switch. (2) Engine Maintenance Control Switch. (3) Engine Maintenance Speed Control Switch. (4) Electronic Ignition Reset Push-Button.

Engine Control Switch (1)

The Engine Control switch communicates the status of the system to the Engine Status Control Module. The switch has three positions: OFF/RESET, MAINTENANCE, and AUTO. Each position is described in the following paragraphs.

OFF/RESET

This position is used when a system shutdown has occurred or the system is not required to run at the present time. Placing the Engine Control switch (ECS) in this position will reset shutdown alarm conditions if all shutdown conditions have been eliminated.

MAINTENANCE (MAINT)

This position is used when the operator intends to run only the engine. When this position is selected the Engine Maintenance Control switch becomes "active".

AUTO

This position is the "normal" position when running the engine as part of the Chiller System. The switch must be in this position for the York MicroPanel to operate the Chiller. Moving the switch from the AUTO position, during normal operation, will result in system shutdown.

Engine Maintenance Control Switch (2)

The Engine Maintenance Control switch (EMCS) is a two-position (Stop or Start/Run), switch. This switch is only active when the Engine Control switch is in the "MAINT" position and initially, this switch must be in the STOP position.

Show/hide table

Never manually engage the clutch and attempt to run the system without the York MicroPanel controls. Manually engaging the clutch can cause severe damage to the compressor and possibly result in personal injury.

STOP

This position is the same as OFF/RESET on the Engine Control switch when the Engine Maintenance Control switch is active. This switch must be in the STOP position to activate the switch and prevents unintentional engine starts when moving the ECS from AUTO to OFF/RESET.

START/RUN

This position should be selected to run the engine only. The engine can be run at Idle or rated speed for engine maintenance. Selecting this position will immediately pre-lube (if equipped) and start the engine.

Engine Maintenance Speed Control Switch (3)

The Engine Maintenance Speed Control switch (EMSC) is a three-position switch. The switch has a PURGE, IDLE, and RATED function. The switch is only active when the Engine Control switch is in the "MAINT" position, except for the PURGE function.

PURGE

This function is used to purge the system of any fuel. This helps avoid the accidental ignition of gas left in fuel lines or exhaust system. This gas could cause an explosion during restart after a system shutdown. Anytime there is an Emergency Stop, either initiated by the York MicroPanel, Cat ECP, or the operator, the operator must purge the engine before attempting a restart. The operator should run the purge function for 15 seconds to make sure that all the gas is out of the fuel system. (See the "Emergency Stop Reset Sequence" for additional information.)

IDLE

This position should be selected to run the engine manually at low idle speed.

RATED

This position should be selected to run the engine manually at rated speed.

Electronic Ignition System (4) (Not On G3406)

DIAGNOSTIC RESET

After an EIS alarm or shutdown, the Diagnostic Reset push-button must be pressed to reset the EIS system for the Caterpillar Gas Engine. For additional information on resetting, refer to the "Alarm Reset Sequence" or the "Emergency Stop Reset Sequence" sections in this manual.

Operating Procedure

To operate the Chiller System:

1. Place the Engine Control switch, located inside the Caterpillar ECP, in the AUTO position. Make sure the Engine Maintenance Control switch is in the STOP position and the Engine Maintenance Speed Control switch is in the IDLE position, as shown below.

Typical Interior Control Panel (except G3406)

G3406 Interior Control Panel

2. Push the Start switch on the York MicroPanel (not shown) to the RUN position. The system is now ready to start.

Engine Monitoring

The engine control panel contains an Engine Status Control Module (1), a Shutdown Module (2), and an Alarm Module (3). These modules provide the operator with information on vital engine parameters, alarms, and shutdown signals. An Emergency Stop button (4) is also provided on the control panel. The following is a detailed description of the function and logic of these modules.

Engine Control Panel
(1) Engine Status Control Module. (2) Shutdown Module. (3) Alarm Module. (4) Emergency Stop Button.

Engine Status Control Module (1)

Engine Status Control Module (ESCM)

The Engine Status Control Module (ESCM) provides engine monitoring and protection. The ESCM displays real time values for engine hours, engine speed, battery voltage, engine oil pressure, and engine coolant temperature. The ESCM will toggle through the various engine parameters, while an arrow on the LCD display (1) indicates which parameter is currently being displayed.

To monitor an individual parameter, simply press select button (2) on the ESCM while that parameter is displayed. Press the button again to return to the display function.

The ESCM has six built-in safety shutdown indicator LEDs (3). They include overcrank, overspeed, high coolant temperature, low engine oil pressure, emergency stop, and an auxiliary shutdown. Each shutdown is described in this section.

If, during the operation of the engine, a fault occurs which stops the engine, a red LED on the ESCM will be illuminated. This red LED indicates, to the operator, that the engine has been shut down for a fault condition, and will not be restarted until the condition has been eliminated, or the source of the fault has been located and corrected.

Overcrank

When the Cycle Crank feature is enabled, the ECM automatically cranks-rests-cranks the engine for the selected time period. If the engine fails to start within the selected total crank time, the ECM executes an overcrank fault.

Overspeed

An Overspeed Shutdown will occur when the engine speed exceeds the maximum speed setting of the ESCM. If engine speed exceeds 2100 RPM (G3400) or 1680 RPM (G3500) for the Chiller System, the engine will shut down on an overspeed fault.

High Coolant Temperature

If, at anytime during engine operation, the engine coolant temperature rises above 109°C (228°F), the engine will be shut down.

Low Engine Oil Pressure

If the engine oil pressure drops below 206 kPa (30 psi) when above 1130 RPM (G3400) or 1210 RPM (G3500), the engine will shut down.

Emergency Stop

The operator may choose to stop the chiller function if damage to the system is likely to occur. Pushing Emergency Stop button (4) will shut down the system and the Emergency Stop warning light will illuminate on the ESCM.

Auxiliary Shutdown

The Auxiliary Shutdown is used by the PLC and York MicroPanel to terminate engine operation due to Chiller driveline and compressor shutdowns. If this fault occurs, check the ECP alarm and shutdown modules and the York MicroPanel status button to determine the fault condition.

If a fault condition occurs while the engine is cranking, the ECM terminates and will not allow cranking. The ECM displays the applicable diagnostic code or turns on the appropriate LED.

Shutdown Indicator Module (2)

Shutdown Indicator Module

The Shutdown Indicator Module provides a visual indicator that a fault has occurred on the Chiller driveline and has shut down the Caterpillar Gas Engine. The following is a listing of the parameters set for engine shutdown in the event that one of these faults occurs. If a fault occurs, it should be corrected, and the engine purged for 15 seconds prior to the engine being restarted.

Low Engine Coolant Shutdown

The coolant in the jacket water expansion tank is vital to the continued operation of the engine. If the coolant level in the jacket water expansion tank drops to a low level, the engine may not be able to build up enough pressure to carry the coolant throughout the cooling lines in the engine block. If this occurs, the engine will overheat and possibly cause major damage.

To avoid this problem, this sensor was added to shut down the engine when the fluid level is too low. This shutdown should not be used to replace a regular maintenance schedule for the engine. The operator should check the engine fluid levels on a regular basis, outlined by the appropriate Service Manuals.

Low Gearbox Oil Pressure Shutdown

The engine gearbox operates with pressurized plates. The gear oil applies pressure to the plates and gears within the gearbox to move the gears together. If the pressure within the gearbox is too low, the plates will not have sufficient lubrication and could fail. If this shutdown occurs, the gearbox lubrication pump should be checked for proper operation. This includes checking the filter.

High Gearbox Oil Temperature Shutdown

Since the gearbox is a large transmission, and there are gears and plates on the interior working with each other, the gearbox is subject to increased temperatures. The increase in temperature is due to friction between the plates and gears. The object of the gear oil is to draw the heat away from the gears and plates. The gear oil is then cooled by the engine cooling system.

If the temperature of the gearbox increases, and the gears, plates, and oil are not cooled properly, the gearbox can be damaged by overheating. If the engine protection system gives a High Gearbox Temperature Shutdown, the operator or maintenance technician should again determine the reason this fault occurred, and correct it prior to restarting the Chiller System.

Electronic Ignition System Shutdown (Not On G3406)

The Electronic Ignition System (EIS) is one of the main controlling systems of the Gas Engine Chiller because it controls engine cylinder timing.

If there is a fault in the EIS, the performance of the engine may be compromised. For information on correcting the fault, refer to the Caterpillar Electronic Ignition System (EIS) Electronic Troubleshooting Guide. A Digital Diagnostic Tool (DDT) will be required for this procedure.

Clutch Engage Failure Shutdown

Clutch pressure is monitored by the Cat ECP. If the clutch pressure of the Chiller driveline does not maintain 620 kPa (90 psi) for G3408, G3412, G3508, G3512 or 758 kPa (110 psi) for G3516 during normal operation, a fault has occurred, and the engine will shut down. The problem must be corrected before restarting the engine.

PLC Failure Shutdown

The PLC has been programmed to output a signal to a watchdog timer. If the PLC fails to output this pulse to the timer, the engine will shut down. This also provides a 24 VDC power failure signal (most likely reason for a PLC failure).

Sensor Failure Shutdown

If any of the sensors fail (short circuit or open circuit) the engine control panel and engine ignition system can no longer control and monitor the engine will shut down and turn on the Sensor Failure Shutdown LED. To determine which sensor has failed, press the Lamp Test, and the failed circuit will flash.

Alarm Indicator Module (3)

Alarm Indicator Module

An Alarm Indicator Module has been incorporated to warn the operator of faults that may result in a system shutdown. It also warns of minor faults that if taken care of properly will not damage the engine.

The Alarm Indicator Module is designed with a Lamp Test push-button (1), which will illuminate all the lamps in all of the annunciator modules on the front of the engine control panel.

The Alarm Indicator Module also has a horn to warn the operator. In the case of a shutdown or alarm condition, the alarm will sound. To turn the alarm off, use the push-button (2) next to the horn marked "ALARM SILENCE". If the condition causing the alarm is not corrected, the horn will sound again in one minute.

High Engine Coolant Temperature Alarm

If the engine coolant temperature has exceeded the alarm set point, but has not reached the shutdown set point, this alarm light will come on and sound the horn. The operator should take corrective measures to bring the engine coolant temperature down. If the operator does not correct this alarm condition, the engine coolant temperature could continue to rise to the shutdown set point. This can cause a system shutdown and possible damage to vital engine components.

Low Engine Oil Pressure Alarm

If the engine oil pressure is low, the oil cannot reach the vital engine parts which need lubrication. If the engine oil pressure drops to a level which reduces lubrication, a Low Engine Oil Pressure Alarm condition will sound. The operator should follow the correct troubleshooting procedures to determine the reason for the fault condition and correct the problem.

Electronic Ignition System Alarm (Not On G3406)

The Electronic Ignition System (EIS) is one of the main controlling systems of the Gas Engine Chiller because it controls engine cylinder timing.

If there is a fault in the EIS, the performance of the engine may be compromised. For information on correcting the fault, refer to the Caterpillar Electronic Ignition System (EIS) Electronic Troubleshooting Guide. A Digital Diagnostic Tool (DDT) will be required for this procedure.

System Not In Auto Alarm

The System Not in Auto alarm, will come on anytime the Engine Control switch is not in the AUTO position. When the Engine Control switch is not in AUTO, the Chiller system will not function. This alarm will occur when the engine is operated in the maintenance mode during engine service. The Engine Control switch should be returned to the AUTO position prior to Chiller operation.

Low Battery Voltage Alarm

The Low Battery Voltage alarm will come when the voltage potential from the batteries is below 19 VDC. If this alarm comes on, change or charge the batteries to 24 VDC.

Low Gearbox Oil Pressure Alarm

If the oil pressure in the gearbox drops below the alarm setting, the Low Gearbox Oil Pressure alarm will be illuminated. The operator should take steps to increase the oil pressure in the gearbox to avoid a shutdown. Check the gearbox for leaks and the operation of the oil pump motor as possible causes of the low oil pressure.

Alarm Reset Sequence

The following procedure should be followed to clear engine and driveline related alarm conditions:

1. Alarm conditions will flash the appropriate alarm LED and sound the horn on the Alarm Module until the Alarm Silence button is pressed. Once the Alarm Silence button is pressed, the LED will stay on continuously and the horn will turn off.

2. If the alarm condition is corrected after the Alarm Silence button is pressed, the LED will turn off, indicating the alarm condition has returned to a normal operating state.

3. If the alarm condition does not clear itself, the LED will remain on continuously until the fault is corrected.

NOTE: Electronic Ignition System alarms are the one exception to the above procedure. The "Diagnostic Reset" push-button, located on the inside door, must also be pressed to reset the EIS alarm condition, in addition to the above procedure.

The following procedure should be followed to clear Chiller related alarm conditions. York Chiller related alarms are displayed on a Vacuum Fluorescent Display (VFD) on the front of the York MicroPanel.

1. The York MicroPanel will prompt the operator to "Press Status" to acknowledge the alarm condition.

2. Press the Status button next to the VFD to view the alarm condition. The screen will update and display the indicated alarm condition.

3. If the alarm condition clears itself, the prompt to "Press Status" will no longer be displayed.

4. If the alarm condition does not clear itself, the prompt to "Press Status" will continue to be displayed until the condition causing the alarm is corrected.

Emergency Stop Reset Sequence

Safety shutdowns can be initiated by the Engine Control Panel (ECP) or by the York MicroPanel. Safety shutdowns will also require both panels to be reset.

The system will run through a safety shutdown sequence when a safety shutdown has occurred. The sequence will include running the compressor lubrication pump and the gearbox lubrication pump for up to four minutes. The safety shutdown will not be active until the system has run through this shutdown sequence.

NOTE: Wait for the sequence to complete before executing the following procedure (with the exception of alarm silence) to allow for proper lubrication of the compressor and gearbox.

To troubleshoot and resolve the cause of problems, contact the appropriate personnel (York technician, Caterpillar dealer, etc.). Data to help troubleshoot problems can be obtained from the ESCM York MicroPanel and the DDT.

The following procedure should be followed to reset the system after a safety shutdown.

1. Press the Alarm Silence push-button on the ECP to turn off the horn.

2. Move the Engine Control switch to the OFF/RESET position to reset the ECP. Leave the Engine Control switch in this position until this procedure is complete.

3. Place the START/RUN/STOP toggle switch on the York MicroPanel in the STOP position.

4. If emergency stop button was pushed to initiate an emergency stop, reset the emergency stop button.

5. Press the Diagnostic Reset button if the safety shutdown was initiated by the EIS system or caused an EIS Shutdown Diagnostic.

NOTE: The Diagnostic Reset push-button is not on G3406 Engines.

6. Press the Warning Reset push-button on the York MicroPanel to reset the system.

NOTE: If the compressor lubrication pump is still running, the system will not reset.

If the system has been reset after this procedure, and the reason for the shutdown has been corrected, the following procedure should be followed before starting the Caterpillar Gas Engine.

7. Place the Engine Control switch in MAINT position, and turn the engine Maintenance Speed Control switch to the PURGE position.

8. Turn the Engine Maintenance Control switch to the START/RUN position and hold it for 15 seconds while the engine cranks. This will allow any residual fuel to be removed from the engine and exhaust system. Return the switch to the STOP position.

9. Repeat Steps 1 through 5 to reset the system.

10. Place the Engine Control switch back in the AUTO position and close the door.

11. The system should now be reset.

Controllers

Controllers (G3406 ECP)
(1) Programmable Logic Controller. (2) Woodward Electronic Governor.

Programmable Logic Controller (PLC)

Programmable Logic Controller (PLC)

The Programmable Logic Controller (PLC), is a General Electric series 90-30 controller. The PLC provides a means to control and monitor the engine and driveline without using a large number of robust relays. The PLC utilizes digital logic, analog signals, and relay logic in one convenient package.

The Gas Engine Chiller design uses two Digital Input cards, a Digital Output card, a Relay Output card, an Analog Input card, and a Power Supply. The program for the control, operation, and monitoring of the Gas Engine Chiller is loaded into the CPU and programmed into an Electronically Erasable/Programmable Read Only Memory chip. This EEPROM keeps the program and the configuration, so that during a power loss situation, the program does not have to be downloaded again. The power supply uses a lithium battery to provide backup power to keep the information in memory from being erased.

Electronic Governor

Woodward 2301A Electronic Governor

The Woodward 2301A Electronic Governor provides precision engine speed control. The 2301A control continuously measures engine speed and makes the appropriate correction to the engine fuel setting through an actuator connected to the fuel system on the engine.

The engine speed is sensed by a magnetic pickup. As the teeth of the flywheel ring gear go through the magnetic lines of force around the pickup, an AC voltage is produced. The ratio between the frequency of this voltage and the speed of the engine is directly proportional. An electric circuit inside the control box senses this AC frequency. In response, it sends a DC voltage from the control, inversely proportional to engine speed, to the actuator.

The actuator is connected to the fuel system by mechanical linkage. It changes the electrical input from the control box to a mechanical output that changes the engine fuel setting. For example, if the engine speed was more than the speed setting, the control box will decrease fuel to the engine.

The Start Fuel Limit Potentiometer is used to control the amount of fuel the engine receives during start-up. The fuel limiting function is turned off automatically when the speed control takes over. The speed fail safe circuit will stop all voltage output to the actuator if the magnetic pickup signal drops below 1 VDC or 100 CPS. A magnetic pickup failure or slow engine cranking will cause the actuator to move to the "Fuel Off" position. The engine will not start if the magnetic pickup signal has a failure.

For more information on the Woodward 2301 variable speed controller, refer to 2301A Speed Control with mA Speed Setting Input, RENR1345.