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CMC TECHNICAL REFERENCE MANUAL
1X36003 Version 2.52
1996-1999 Ingersoll-Rand Company
Date of Issue: 18-Oct-1999
45
2/3
SYSTEM
SETTINGS
INFO
Not Ready
Remote
Trip
Event Name Time Date
1 Low Oil Pressure Trip 09:18:44 0720
2 Low Oil Pressure Alarm 09:18:43 0720
3 Reset key pressed 09:18:34 0720
4 Low Oil Pressure Trip 09:08:43 0720
5 Low Oil Pressure Alarm 08:58:23 0720
6 Load key pressed 08:24:01 0720
7 Start key pressed 08:23:12 0720
Troubleshooting Example
The following example will serve as a guide to follow when troubleshooting specific
problems.
Problem Indication:
Plant air pressure is low and the CMC OUI is found
as shown.
Probable Cause Determination:
1.
The machine Tripped on Low Oil Pressure, which means the oil pressure, was below
the Oil Pressure Trip Value. Figure 12 leads to the assumption that the problem is
either compressor or I/O related, because the fault is Event Logged. There are two
most likely causes for this event.
a) Actual oil pressure is low.
i)
The prelube pump is found to be running and installation of a calibrated pressure
sensor shows the actual oil pressure to be above the Oil Pressure Trip Value.
Therefore, the mechanical system is operating correctly.
b) The value read by the CMC is incorrect.
i)
The oil pressure value displayed on Page 2 of the System Folder shows the oil
pressure to be below the test sensor reading and erratic. Additionally, all other
analog input readings are normal and not erratic. Therefore, the problem can be
isolated to the oil pressure, analog input circuit.
ii)
The Pressure Monitoring System (PMS) troubleshooting table, found in the
following section “The Pressure Monitoring System” identifies the probable
cause for an erratic reading as a loose wire/terminal/connector and specifies
Troubleshooting Procedure PMS #1 and 2 as the appropriate procedures.
Trouble Procedure Execution:
Step 1 of PMS #1 requires disconnecting of the pressure transducer (PT) wires at the
transmitter. When this step is performed, one of the connections is found to be intermittent.
When the poor connection is corrected, the erratic reading on the OUI becomes solid.