Understanding drive faults 8 and 168 – Rockwell Automation 20GY PowerFlex 755 with OEM Liquid Cooling Frame 6 and 7 AC Drives User Manual
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Rockwell Automation Publication 20GY-IN001A-EN-P - June 2011
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PowerFlex® 755 with OEM Liquid Cooling Frame 6 and 7 AC Drives
Understanding Drive Faults
8 and 168
All drive fault and alarm descriptions for standard air-cooled drives shown in the
PowerFlex 750-Series AC Drives Programming Manual (publication 750-
PM001) also apply to the PowerFlex 755 with OEM Liquid Cooling Frame 6
and 7 AC drives—except for Faults 8 and 168. Both the standard air-cooled
drives and liquid-cooled drives use these faults, but they operate somewhat
differently for liquid-cooled drives. See
for details.
Table 2 - Drive Faults 8 and 168 Operation for PowerFlex 755 with OEM Liquid
Cooling Frame 6 and 7 AC Drives
Figure 5 - Temperature Sensor and Thermal Switch Circuit
No.
Fault Text
Type
Description/Action
8
Heatsink OvrTemp
Resettable
Fault
The heatsink temperature has exceeded 100% of the drive
temperature. Heatsink over temperature occurs at 85 °C.
This value is stored in drive firmware.
168
HeatSinkUnderTmp
Resettable
Fault
Heatsink temperature sensor is reporting a value below
-18.7 °C (-1.66 °F) or an open thermal switch. Causes
include:
1. Air or coolant temperature is excessively cold; raise
temperature of drive.
2. DC inductor is over temperature and thermal
switch is open; check for blocked or failed power
structure fan.
3. Sensor feedback circuit is open; see
.
J25 on
Power PCB
NTC
Chillplate
DC Inductor
Thermal Switch
NC