2012/11/26 Caterpillar

Engine:

C18 (S/N: ZKB1-UP)

C9 (S/N: X3R1-UP)

Generator Set:

3406 GEN SET (S/N: NKM1-UP)

3406C GEN SET (S/N: ZKC1-UP; C2G1-UP; C5G1-UP; C8G1-UP; C2Y1-UP)

3456 GEN SET (S/N: C1G1-UP; C3G1-UP; C4G1-UP; C2T1-UP)

C15 GEN SET (S/N: T4A1-UP; ZKA1-UP; C5E1-UP; STG1-UP; C5H1-UP; C5L1-UP; NKL1-UP; X4R1-UP; CYY1-UP)

C18 GEN SET (S/N: C6C1-UP; G4C1-UP; N1C1-UP; N1D1-UP; STD1-UP; DKE1-UP; PEJ1-UP; NKK1-UP; NKM1-UP; STM1-UP; EKW1-UP; M1Y1-UP; M1Z1-UP)

C18 MARINE GS (S/N: GBM1-UP)

C9 GEN SET (S/N: C9E1-UP)

Petroleum Engine:

C15 PET GS ENG (S/N: PET1-UP)

Description of Change: The improved exciter rotor design is now used on the Engines and Generator Sets that are listed in Table 1. A more durable exciter rotor design is being implemented to withstand the mechanical stress on the exciter rotor lead lugs which are known to be the greatest in paralleling applications, especially in conditions where reverse VAR or reverse KW events are experienced by the generator. The exciter rotor design contains the following improvements:

• Upgraded exciter rotor lead lugs, as shown in Illustration 1, to lugs of stronger construction to avoid breaking of lugs due to mechanical stress at electrical connection of exciter rotor lead to rectifier assembly.

• Reduced length of exciter rotor lead wire to minimize mechanical stress on lead wire and prevent lug from breaking off at the rectifier assembly.

Adaptable To:

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High voltage may be present. The power source must be disconnected before working on the equipment. Failure to disconnect the power source could result in injury or death. Verify that the equipment is not energized before performing any maintenance. This work must be performed by trained personnel with correct tools and procedures.

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When servicing or repairing electric power generation equipment: Make sure the unit is off-line (disconnected from utility and/or other generators power service), and either locked out or tagged DO NOT OPERATE. Remove all fuses.

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Bodily contact with electrical potential can cause bodily injury or death. To avoid the possibility of injury or death, ensure that the main power supply has been disconnected before performing any maintenance or removing any modules.

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Only persons with training in electrical installations must carry connections to the generator. The generator must be wired correctly. A fire or electrocution could result from wiring that is incorrect. The generator is capable of generating high voltages. Ensure that the generator is not on while the connections are being made. Follow these two steps in order to prevent accidental starting: Isolate the DC breaker. Disconnect the DC supply battery.

Illustration 1	g03322746
Rectifier Assembly mounted to drive end view of exciter rotor (1) Exciter Rotor lead wire and lug (2) Rectifier assembly (mounted to aluminum plate by four screws: aluminum plate, under rectifier assembly, mounted to exciter rotor laminations by three thread-forming screws)

Illustration 2	g03322747
Exciter Rotor shown from nondrive end view of generator (3) Balance weight (located in slots)

Perform the following steps when repairing or replacing the rectifier assembly and/or exciter rotor:

High voltage may be present. The power source must be disconnected before working on the equipment. Failure to disconnect the power source could result in injury or death. Verify that the equipment is not energized before performing any maintenance. This work must be performed by trained personnel with correct tools and procedures.

• Shorten each of six rectifier leads. Refer to Illustration 1.

• Replace lugs with stronger construction lugs, such as 6B-2864 Terminal .

• Inspect integrity of aluminum rectifier assembly plate mounting to the exciter rotor laminations.

• If the aluminum rectifier assembly plate is found not to be firmly mounted to the exciter rotor laminations, re-tap three new holes into the exciter rotor laminations and mount plate firmly or replace the exciter rotor assembly and plate.

• The mounting hardware used are three thread-forming screws and the integrity of mounting requires holes to be new.

• If the exciter rotor is removed to make repair or for replacement, care must be taken to assure the combination exciter rotor and main rotor assembly are mechanically balanced.

Note: The exciter rotor for this design generator is not balanced as a separate component. Full confidence in mechanical balance can only be 100% achieved, if balanced with a balancing machine. Alternatively, an acceptable level of balance can be achieved by removing weights from the original exciter rotor, and installing the weights in the exact same position on the replacement exciter rotor.

Note: Accessing of weights inside the exciter rotor is done only by removing the cover plate that is riveted to the exciter rotor at the non-drive end view of the generator (not by removing the aluminum rectifier assembly plate mounted on the drive end of the exciter).The improved exciter rotor design is adaptable to and effective with the serial numbers that are listed in Table 1.