Hobart 120CU20, Operation And Maintenance Manual With Illustrated Parts List

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OM-2228 / Operation and Maintenance Manual
120CU20 / Series 500120 / 400 Hz. Generator Set
October 15, 2013 Chapter 2-4
Page 6
Figure 1 Fault Meter Display
d) Operation Monitoring
While applying power to an aircraft, the GPU continually monitors all critical circuits and operating
electrical values.
During 400 Hz AC and 28.5 VDC (if supplied) operations, the GPU continually performs Command
“70” (Engine Run Mode). When a fault is detected during operation, this
Command and the detected
Fault are indicated in the “ FAULT CODE ” display.
By referencing the Command and Fault Code chart, the GPU state and exact fault can be
determined. When the fault is reset and the GPU restarted, the GPU may often detect the fault again
revealing additional information. This method yields a high degree of troubleshooting accuracy.
Fault meter display example shown above: If the engine shuts down with the above fault code,
“70.67”, the engine ceases operation due to high coolant temperatures in the engine. The “70”
represents the command the GPU was executing at the time of the fault and shutdown (Command
“70” indicates an Engine Run Mode command.). The “67” represents the fault code that indicates the
action taken by the control system upon faulting (Fault “67” indicates a Stop Mode fault which shuts
the GPU down.).
e) Extracting Fault Code Information
In the event the GPU fault code history information is required for troubleshooting, all fault codes
stored in the control system’s memory (i.e. data records) can be extracted and viewed on the Fault
Meter Display (starting with the last fault code and scrolling backward through all previous fault
codes). The following are the procedures for extracting the fault code information:
(1) Pull the “
EMERGENCY STOP ” button out.
(2) Press the “ LAMPS ” push-button to turn on the control box lights.
(3) Press the “ TEST/RESET ” push-button and hold for 2 to 3 seconds until the data record number
appears on the display (See Figure 2).
70.67
Command Fault
Fault Codes