Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C Frame) - Classic Control - Manual (Page 326)

5-18 Functional Description
7000L-UM300I-EN-P – June 2013 7000 “C” Frame
Except for the dc link over-current, line side dc link over-voltage and
machine side dc link over voltage, the drive protection is customer
configurable in the software. Adjustable parameters specifying the
trip level and time delay are provided for each fault (see Medium
Voltage AC Drive Parameters, Publication 7000-TD001_-EN-P).
A detailed list of all the faults and warnings (alarms) is provided in
Chapter 7 (Troubleshooting).
The response to a drive alarm falls into three categories:
For Class 1 faults (with the exception of dc link over-current, line
side dc link over-voltage and machine side dc link over-voltage), the
line converter is immediately phased back to retard limit until the dc
link current drops to zero. The gating for both converters is disabled
and the contactors (if installed) are opened. At this point the motor
will coast and its speed will depend on the characteristics of the load.
For some high inertia loads, the motor may coast for a long time.
The dc link over-current and dc link over-voltage (line and machine)
are special cases in that the fault detection is performed by hardware
because a very fast response is required. The hardware fault detection
responds to instantaneous values. Also the drive response to these
faults is different from other Class1 faults because it freezes the
SGCT gating (both converters if a PWM rectifier based drive and
only the inverter side if a 6P/18P SCR drive) until the dc link current
has dropped to zero. The gating is then disabled and contactors are
opened.
For Class 2 faults the motor is brought to a normal stop before the
gating is disabled and the contactors opened. Typical examples of
Class2 faults are motor overload, drive overload and loss of load.
Line/Machine Converter
Protection