Main Termination Blocks on Gensets{7553} Caterpillar

Engine:

C2.2 (S/N: XYE1-UP)

C4.4 (S/N: XYC1-UP; XYD1-UP)

Introduction

Under certain conditions such as repeated power washing, the termination blocks for the main phase and for the earth ground on the outlet panel can become damaged. This damage may cause the resistance of the electrical insulation to deteriorate below an acceptable level.

Note: The termination blocks should be free from dirt and from contamination. Clean these termination blocks by wiping. Do not use power washing as a method for cleaning these termination blocks.

In order to avoid a failure of the genset, inspect the termination blocks. perform the following test procedure in order to properly inspect the termination blocks. If the termination blocks fail either test, then immediately replace the termination blocks with the improved parts that are listed in Table 1, or Table 2.

Note: The replacement parts for products that are equipped with termination blocks which are 122 mm (4.80 inch) in length are listed in Table 1. The replacement parts for products that are equipped with slightly longer termination blocks which are 142 mm (5.59 inch) in length are listed in Table 2.

Test Procedures

Visual Inspection Test

1. Ensure that the genset is switched off.

2. Examine the termination blocks on the termination panel and note if there are any signs of cracks in the material. Refer to Figure 1.

   Note: This damage may allow the buildup of moisture within the termination block. This moisture may cause failure when the genset is operated.

Illustration 1	g01304706
(1) Water Damage Marks (2) Material Cracks

Electrical Insulation Resistance Test

1. Ensure that the genset is switched off.

2. Discharge the capacitance of the windings by shorting each phase to earth.

   Perform the following test for each phase individually.

   Note: Do not disconnect more than one phase at a time In order to ensure that the cables are reconnected correctly for each phase.

3. Remove the breaker cable, the load cable (if equipped) and the copper link from the termination connection.

4. Use an insulation tester in order to measure the resistance at 500V between an earth ground on the chassis and each individual stud.

   The minimum acceptable electrical insulation resistance value is 100M ohms. Values below 100M ohms are considered to be failures.

   Note: The 16th Edition of the IEE Regulations specifies a minimum insulation resistance of 0.5M ohm for electrical wiring and installations. However, the insulation resistance of an individual component would normally be much higher. The measured values for insulation resistance on termination blocks are above 1G ohms on all new product. Samples that have undergone water damage can test as low as 0.5M ohm for a short amount of time after the removal of water. The test values of these samples can rise to 100M ohm or higher when the samples have dried completely. Therefore, Caterpillar recommends a minimum insulation resistance of 100M ohm.

5. Reconnect the the breaker cable, the load cable (if equipped) and the copper link.

6. Test the genset in order to verify correct operation.

Solution

Installation of the 289-9155 Plug

If no failures are recorded but future moisture damage is anticipated, then Caterpillar recommends the following step in order to acquire added protection.

1. Install a 289-9155 Plug over the mounting screws of the chassis in order to reduce the collection of moisture which may cause future deterioration of the material.

Procedure for the replacement of the termination block

If any of the termination blocks fail either of the previous tests, replace all termination blocks on the affected genset.

1. Ensure that the genset is switched off.

2. Discharge the capacitance of the windings by shorting each phase to earth.

3. Remove the breaker cables and the load cables (if equipped).

4. Remove the termination blocks from the chassis.

5. Use the M12 nuts in order to install the new terminal block with the integral mounting stud. Also, install the other parts from the removed assembly.

   Note: Existing studs are 1/2 inch while the new studs are M12 thread. (The existing washers do not need to be replaced.) See Table 1 for part numbers.

6. Reconnect the breaker cable and the load cable (if equipped).

Required Parts

Use Table 1 in order to replace the parts on products that were equipped with termination blocks which are 122 mm (4.80 inch) in length.

Use Table 2 in order to replace the parts on products that were equipped with termination blocks which are 142 mm (5.59 inch) in length.