D7E Track-Type Tractor Power Train Systems Caterpillar

Electrical Maintenance Guidelines

Usage:

D7E TAN

Read and follow the guidelines that are outlined in this section of the manual. The guidelines cover the procedures and guidelines that must be followed prior to performing a maintenance procedure and during a maintenance procedure.

In addition to these guidelines, the user should be aware of any federal, state, or local maintenance guidelines. Follow all guidelines that apply to the operation and maintenance of the machine in your area.

Electrical Maintenance Guidelines for the Power Train Electric Drive System and the Accessory Power System.

This section covers the procedures and guidelines that must be followed when a service procedure or a maintenance procedure is required under the following conditions:

An electrical service procedure must be performed on any component in the Power Train Electric Drive System or the Accessory Power System after Engine shutdown.
An electrical or mechanical service procedure must be performed with the 24 VDC control system energized. (Key start switch in the ON position and Engine OFF).
An electrical or mechanical service procedure must be performed on the machine 24 VDC control system or a machine mechanical system with the Engine in operation.
A service procedure must be performed on a machine mechanical system with the Engine in operation.

Note: When a maintenance procedure is to be performed on a machine mechanical system only with the Engine OFF, the Safe Shutdown Procedure is not required before the work is initiated.

READ AND FOLLOW THESE PROCEDURES THIS SECTION. ENSURE THAT PERSONNEL THAT ARE TO PERFORM SERVICE OR MAINTENANCE ON THE MACHINE ARE ACTING IN A RESPONSIBLE MANNER.

DO NOT PERFORM ANY TYPE OF PROCEDURE ON THE POWER TRAIN ELECTRIC DRIVE SYSTEM COMPONENTS OR THE ACCESSORY POWER SYSTEM COMPONENTS WHEN THE ENGINE IS IN OPERATION.

Note: If you are not familiar with the components in the Power Train Electric Drive System and the Accessory Power System, do not perform maintenance on the machine. Refer to the Systems Operation, "Power Train Electrical System" section of this manual in order to be able to identify the components that are used in these systems.

When a test procedure, an adjustment procedure, or a 24 VDC electrical system procedure does require that the Engine is operating, certain safety guidelines must be followed. Refer to the “Performing Maintenance Procedures With The Engine And Generator Operating” section further on in the text for instructions.

The amber Hazardous Voltage System Energized Indicator is used only to indicate the status of the DC Power Bus voltage and the DC Accessory Power Bus voltage. When hazardous voltage levels are present in the systems, the indicator is designed to illuminate. When the key start switch is moved to the OFF position, the Hazardous Voltage System Energized Indicator is designed to remain illuminated until the voltage in the DC system is discharged to 50 VDC or less. The Electric Water Pump will continue to operate after key off for a short time. This feature will discharge the DC voltage quickly. Normally, the voltage should decrease to under 50 VDC in less than 5 seconds. However, The discharge could take as long as 5 minutes under some abnormal circumstances. The Hazardous Voltage System Energized Indicator is designed to turn OFF when the voltage is less than 50 VDC. Under normal machine conditions, the Hazardous Voltage Present System Indicator circuit is designed to operate regardless of the state of the battery disconnect switch.

50 VDC is the standard for determining when the voltage is at a level where work on the electrical system can be permitted.

Note: The Hazardous Voltage System Energized Indicator is to be used as a visual aid in order to indicate the monitored status of the DC Power Bus. The Hazardous Voltage Present System Indicator is not designed as an absolute indication that the DC Power Bus has been discharged. Regardless of the state of the Hazardous Voltage System Energized Indicator, always assume that there is hazardous voltage present in the system. Always personally verify that the voltage is discharged. Measure the DC Power Bus voltage with a voltage meter between any exposed conductors and frame ground. Verify that the voltage is below 50 VDC before any service is performed on any of the hazardous voltage system components.

Safe Shutdown Procedure for Electric Drive Tractors

This procedure must be performed when:

An electrical service procedure must be performed on any component in the Power Train Electric Drive System or the Accessory Power System after Engine shutdown. Included is opening a hazardous voltage enclosure that houses hazardous voltage connections. Also included is the disconnection of any hazardous voltage cable connectors in the AC system or the DC system.

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The Power Train Electric Drive System and the Accessory Power System will contain hazardous voltage levels during machine operation and for a period of time after machine shutdown.
Do not remove any covers that will expose energized electrical components while the engine is operating. Do not remove any covers that will expose the energized electrical components while the components remain energized following an engine shutdown.
Do not perform any type of electrical maintenance on the orange hazardous voltage conductors, the power train components or the accessory power system components while the engine is operating.
Do not perform any type of electrical maintenance on the orange hazardous voltage conductors, the power train components or the accessory power system components while the components remain energized following an engine shutdown.
Always perform the safe shutdown and de-energizing procedure before performing electrical service on the Power Train Electric Drive System or the Accessory Power System.

Failure to follow these instructions could result in personal injury or death.

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In order to avoid the build up of hazardous live voltages on the exposed surfaces, all grounding wires must be properly connected at all times during engine operation.
Any disconnected grounding wires (including the grounding bond wires, the conductor shield wires, the power inverter grounding straps and the component housing grounding straps) must be properly reconnected before the engine is started.

Failure to follow these instructions could result in personal injury or death.

Procedure:

Turn the key start switch to the OFF position.
After the Engine has shutdown, turn the key start switch to the ON position. Do not start the Engine.

Use the Monitoring System Display to check the status of the DC Power Bus voltage. Confirm the voltage measurements of “DC Power Bus 1” and “DC Power Bus 2” are less than 50 VDC. If the voltages are above 50VDC, monitor until the levels are less than 50 VDC. Once the displayed DC voltages are less than 50 VDC, continue to the next step.

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Illustration 1	g02475911
The Battery Disconnect Switch Assembly located under the access cover on the upper left fender of the machine. (1) Hazardous Voltage System Energized Indicator (2) Engine Jacket Water Heater Plug In (3) Battery Disconnect Switch (4) Ground Level Access Lighting Switch (5) Ground Level Shutdown Switch

Access the battery disconnect switch assembly located under the access cover on the left fender of the machine.
Observe the state of the amber Hazardous Voltage System Energized Indicator. The indicator is designed to turn OFF when the voltage of the “DC Power Bus 1” and the “DC Power Bus 2” is discharged to 50 VDC or less. The indicator should not be illuminated.
Note: If incorrect operation of the Hazardous Voltage System Energized Indicator is observed or suspected, resolve the problem before the machine can be operated. Refer to the Implement Electronic Control System, D7E T4i Implement Book. Perform the troubleshooting procedures for the CID 3242 diagnostic code in order to determine the cause of the Hazardous Voltage System Energized Indicator problem.
In order to check the operation of the Hazardous Voltage System Energized Indicator, perform the following indicator test when the indicator is NOT ILLUMINATED: While observing the indicator, turn the battery disconnect switch to the OFF position. Wait a few seconds. Turn the battery disconnect switch to the ON position. When the battery disconnect switch is turned to the ON position, the amber Hazardous Voltage System Energized Indicator will illuminate briefly and then turn OFF. This sequence indicates that the operation of the indicator circuit is correct. However, always assume that hazardous voltage could still be present in the system.
Turn the battery disconnect switch to the OFF position and lock out.
If no AC or DC hazardous voltage conductors will be exposed during a procedure, service can now be performed. If an AC connection enclosure is opened or if a hazardous voltage DC connector is disconnected, use a voltage meter to measure DC voltage between any exposed conductors and frame ground. Do not make personal contact with the exposed conductors until the voltage between the conductors and frame ground has been measured. Verify that there is less than 50 VDC between any exposed AC or DC hazardous voltage conductors and frame ground. Measure for voltage before any other action is taken.

Performing Machine Maintenance with the Key Start Switch ON and the Engine OFF

These guidelines must be followed when:

An electrical or mechanical service procedure must be performed with the machine 24 VDC machine control system energized with battery power. (Key start switch in the ON position and Engine OFF).

DC VOLTAGE IS PRESENT IN THE POWER TRAIN ELECTRIC DRIVE SYSTEM AND THE ACCESSORY POWER SYSTEM FOR A SHORT PERIOD AFTER MACHINE SHUTDOWN.

WHEN THE MACHINE CONTROL 24 VDC ELECTRICAL SYSTEM IS SERVICED, FOLLOW THE SAFE SHUTDOWN PROCEDURE. THE PROCEDURE IS OUTLINED IN THE PREVIOUS SECTION. PERFORM THE PROCEDURE BEFORE ANY ACTION IS TAKEN.

When a procedure requires that the key start switch and the battery disconnect switch are moved to the ON position, DO NOT START THE ENGINE.

When the key start switch and the battery disconnect switch are in the ON position, battery power will be supplied to all control modules.

Note: When any AC or DC conductors are exposed or disconnected, a voltage meter must be used to measure DC voltage. Measure between all of the exposed hazardous AC or DC voltage conductors and frame ground. Measure and verify that less than 50 VDC is present between the exposed conductors and frame ground.

Performing Maintenance Procedures with the Engine and the Generator Operating

These guidelines must be followed when:

An electrical or mechanical service procedure must be performed on the machine 24 VDC machine control system or mechanical system with the Engine in operation.

DO NOT PERFORM ANY TYPE OF PROCEDURE ON THE POWER TRAIN ELECTRIC DRIVE SYSTEM COMPONENTS OR THE ACCESSORY POWER SYSTEM COMPONENTS WHEN THE ENGINE AND THE GENERATOR ARE IN OPERATION.

Daily maintenance procedures and service maintenance for the mechanical systems, the hydraulic systems, and low voltage 24 VDC electrical system can be performed when the Engine and the Generator are in operation.

Most of the procedures that are outlined in the electrical service manuals do not require the Engine and the Generator to be in operation. When possible, perform these procedures with the Engine OFF.

If a hydraulic system or a low voltage electrical system is serviced with the Engine and the Generator in operation, read the following guidelines.

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Failure to follow these instructions could result in personal injury or death.

The following practices must be followed when a maintenance procedure is performed when the Engine and the Generator are in operation.

The grounding bond wires and the conductor shield grounding wires must be connected to the component housing connection points at all times when the Engine and the Generator are in operation.
When the Engine and the Generator are operating and work is being performed close to the electrical power train system components, the accessory power system components and the system conductors, avoid contact with these components when possible. Coming into contact with a grounded electrical system component housing or a grounded system conductor while the engine is operating will not cause a problem. However, if not necessary to be in contact with an energized components while the Engine and the Generator are in operation, avoid the contact.
Do not lay on the electrically energized components or use the components for steps when the Engine is in operation.
Do not use the Power Train Electric Drive System conductors or the Accessory Power System conductors for hand holds or for steps when the Engine is in operation.
Do not use the electrically energized components for bracing or support when the Engine is in operation.
Installation or removal of test equipment or measuring equipment must be done after the Engine is turned OFF and the Safe Shutdown Procedure has been performed.
Any time the machine is to be cleaned using a power wash system, it is recommended that the Engine is OFF, the key start switch is in the OFF position, and the battery disconnect switch is in the OFF position. Avoid direct contact or close operation of the spray wand with the electrical components. Avoid direct power spray on all electrical components, connectors, and seals at all times.
If the machine must be washed with the Engine and Generator in operation, use caution when cleaning around or close to the electrical components. Maintain the largest possible distance between the spray wand and the surface that is being cleaned. Avoid direct contact or close operation of the spray wand with the electrical components. Avoid direct power spray on all electrical components, connectors, and seals at all times.
When a welding procedure is to be performed on the machine, the procedure should be done with the engine is OFF, the key start switch in the OFF position, and the battery disconnect switch in the OFF position. If the welding procedure must be performed with the Engine and the Generator in operation, safely place the welder ground connection as close to the weld area as possible. Refer to the Operation and Maintenance Manual for guidelines on the areas of the machine where welding can be performed.