Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Reference Manual - Manual (Page 46)

46 Rockwell Automation Publication PFLEX-RM003E-EN-E - January 2011
Chapter 1 Detailed Drive Operation
than the motor current limit. After a period of time (typically 1 to 3 minutes), the
function returns the limit to the short term rating.
Closed Loop IT Function
The drive will also adjust the torque current limit level based on the values in
Parameter 358 [Cur Ref TP Data], parameter 313 [Heatsink Temp] and the
thermal characteristics of the drive contained in the power EE memory. Under
normal operating conditions, the function typically sets the limit at 250% of the
continuous drive rating. If the function determines that the power device
junction temperature is approaching maximum, it will reduce this limit to the
level required to prevent additional heating of the inverter. This level could be as
low as the continuous rating of the drive output amps. If the inverter temperature
decreases, the function will raise the limit to a higher level.
Drive Overload Status
Drive Overload Status can be monitored in parameter 346 [Drive OL Status].
• Bit 0 “NTC Shorted” indicates the Negative Temperature Coefficient
(NTC) device has a short circuit.
• Bit 1 “NTC Open” indicates the NTC has an open circuit.
• Bit 2 “HS OverTemp” indicates heatsink temperature is above: 105 °C for
ratings 1.1…11.0 A, 115 °C for 14…34 A, 100 °C for 40…52 A.
• Bit 3 “HS Pending” indicates heatsink temperature is above: 95 °C for
ratings 1.1…11.0 A, 105 °C for 14…34 A, 90 °C for 40…52 A.
• Bit 4 “IT Trip” indicates the drive has exceed the 3 second rating of either
the 150% normal duty rating or 200% of the heavy duty rating.
• Bit 5 “IT Pending” indicates the drive OL integrator is at 50% of the time
out time.
• Bit 6 “IT Foldback” indicates the drive closed loop current limit is in a fold
back condition. The value of the fold back is proportional to the calculated
junction temperature.
• Bit 7 “Jnc Over Temp” indicates the junction temperature has exceeded the
maximum temperature for the power semiconductor device.
Drive Over Temperature
(Frame 9 Only) For frame 9 drives only, the drive over temperature fault is set at 92 ºC. The fault
is detected if the heat-sink temperature, parameter 313 [Heatsink Temp] or
parameter 345 [Drive OL JnctTmp] exceeds 125 ºC.
For frame 1…6 drives the open loop current limit is designed for 25% duty cycle
at 110% output current. However, frame 9 drives allow 10% duty cycle at 110%
output current. The open loop current limit function cannot prevent the drive
from having an over temperature fault.