| Tools Needed | Quantity |
| 9U-7330 Digital Multimeter (1) | 1 |
| 198-4240 Pressure Indicator Tool Gp (Digital) (2) | 1 |
| 1U-5230 Hand Hydraulic Pump (2) | 1 |
| ( 1 ) | If the multimeter is not available, use a multimeter that is capable of measuring resistance or use an ohmmeter. |
| ( 2 ) | If the indicator and the pump are not available, use a hydraulic pump with a digital display. |
For this procedure, a known pressure is applied to the contactor. The pressure simulates engine oil pressure and the pressure closes the normally open contacts. To account for the contactor's hysteresis, the applied pressure must be approximately five percent greater than the setpoint. The pressure is slowly reduced while the contactor is monitored in order to determine whether the contact opens at the desired low pressure. The contactor is adjusted, if necessary.
Before you perform this procedure, determine the setpoint's pressure for the specific contactor. The setpoints are listed in Operation and Maintenance Manual, SEBU7150, "Alarms and Shutoffs".
- Turn OFF the monitoring system's power supply.
- Unscrew retaining bolt (1) and disconnect receptacle (2) from plug (3) .
Note: The terminals are identified on the contactor's receptacle.
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| Illustration 1 | g00872633 |
Side view of a contactor's electrical connection (1) Retaining bolt (2) Receptacle (3) Plug (AA) Identification of the terminals | |
- Connect a multimeter to common terminal 1 and normally open terminal 3 on plug (3). Set the multimeter to the "Ohms" scale.
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| Illustration 2 | g00873670 |
- Turn isolation valve (4) in order to isolate the contactor from the pressure.
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| Illustration 3 | g00872578 |
(4) Isolation valve (5) Nut (6) Cap (A) Isolation valve in the position for normal operation (B) Isolation valve in the position for isolating the contactor | |
- Slowly loosen nut (5) in order to purge the residual pressure from the contactor. Remove the nut. Connect the 1U-5230 Hand Hydraulic Pump to the port. Use a tee in the air hose for the 198-4240 Pressure Indicator Tool Gp (Digital). Loosen cap (6) .
Note: If a tee is not available for the 198-4240 Pressure Indicator Tool Gp (Digital), remove the engine oil pressure line from the bottom of the contactor's mounting block. In this case, connect the 1U-5230 Hand Hydraulic Pump to the port for the engine oil pressure line. Connect the 198-4240 Pressure Indicator Tool Gp (Digital) to the port for nut (5). Turn isolation valve (4) to the position for normal operation.
- Observe the ohmmeter and slowly increase the pressure to the contactor until the pressure is approximately five percent greater than the setpoint's pressure.
If the resistance becomes less than 5 ohms, the contacts are closing correctly.
If either of the following conditions are found, the contacts are not closing correctly:
- The resistance becomes less than 5 ohms before the setpoint's pressure is exceeded.
- The resistance does not become less than 5 ohms after the setpoint's pressure is exceeded.
- The resistance becomes less than 5 ohms before the setpoint's pressure is exceeded.
- Continue to observe the ohmmeter and slowly relieve the pressure from the contactor. Look for changing of the resistance as the setpoint's pressure is reached.
If the resistance becomes greater than 20,000 ohms at the setpoint's pressure, the contacts are opening correctly. No adjustment is needed. Proceed to Step 12.
If either of the following conditions are found, the contacts are not opening correctly. In either case, proceed to Step 8.
- The resistance becomes greater than 20,000 ohms before the setpoint's pressure is reached.
- The resistance does not become greater than 20,000 ohms when the setpoint's pressure is reached.
- The resistance becomes greater than 20,000 ohms before the setpoint's pressure is reached.
- Adjust the pressure to the setpoint's exact pressure. Use a 5 mm Allen wrench to turn the contactor's adjustment dial clockwise until the resistance is greater than 20,000 ohms. The contacts have opened.
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| Illustration 4 | g00872559 |
Adjustment dial for the contactor | |
- Continue to apply the setpoint's exact pressure and slowly turn the contactor's adjustment dial counterclockwise until the resistance is less than 5 ohms. The contacts have closed. Next, slowly turn the adjustment dial clockwise until the resistance is greater than 20,000 ohms.
The contacts have opened.
- Slowly increase the pressure to the contactor until the resistance is less than 5 ohms.
The hysteresis has been exceeded and the contacts have closed properly.
- Continue to observe the ohmmeter and slowly relieve the pressure from the contactor. Look for changing of the resistance as the setpoint's exact pressure is reached.
If the resistance becomes greater than 20,000 ohms at the setpoint's pressure, the contacts have opened correctly. No further adjustment is needed. Proceed to Step 12.
If either of the following conditions are found, the contacts did not open correctly. In either case, repeat Steps 8 through 11 until the contacts open when the pressure is reduced to the setpoint's pressure.
- The resistance becomes greater than 20,000 ohms before the setpoint's pressure is reached.
- The resistance does not become greater than 20,000 ohms when the setpoint's pressure is reached.
- The resistance becomes greater than 20,000 ohms before the setpoint's pressure is reached.
- Purge any residual pressure from the pressurizing pump and remove the pump from the port. Replace cap (6). Install nut (5). Turn isolation valve (4) to the position for normal operation.
- Remove the ohmmeter. Connect receptacle (2) to plug (3). Secure the connection with retaining bolt (1) .