Rockwell Automation MV SMC Flex Motor Controller (for Series K or later) - Manual (Page 129)

Rockwell Automation Publication 1560E-UM051F-EN-P - June 2013 119
Troubleshooting Chapter 9
Control Module Removal The control module is not intended for field repair. The entire module must be
replaced in the event of failure. The following procedure must be followed before
unplugging the control module.
1. Remove all power from the equipment.
2. Make sure that the wires are properly marked and that the program
parameters are recorded.
3. Disconnect all control wires to control module.
4. Loosen the four control module screws.
5. Carefully rotate the module to the left, and unplug the five ribbon cables
from the interface board.
To install control module, follow the reverse order for removal.
Voltage Feedback Circuit
Tests The most straightforward means of checking the feedback circuits is to perform
the “snubber and resistor testing” procedure, found on
page 137 . Another
possible test involves measuring the feedback voltages at the interface board (see
Figure 38 on page 64 ). This can only be done with line voltage applied. If the
motor does not start, it may be necessary to temporarily modify the control
circuit to close the line contactor without applying a start signal to the SMC Flex
module. In this case, the three line voltages (Line A, Line B, Line C) measured
with respect to ground should be approximately 1 volt rms. It is important that
the level in each phase is the same as the other phases, within ± 1%.
If any voltage is well outside this range, there may be a problem either with the
system voltage, or with the voltage sensing board. Note that the load side voltages
(Load A, Load B, Load C) will be very low, since the SCRs are not turned on, and
only a low leakage current flows to the motor.
If the motor will start and run, the line and load voltages should be the same
when the bypass contactor is closed.
SHOCK HAZARD: To avoid shock hazard, ensure the main power has
been disconnected before working on the controller, motor or control
devices. Verify that all circuits are voltage free using a hot stick or
appropriate voltage measuring device. Failure to do so may result in
burns, injury or death.
ATTENTION: When removing the control module, make sure to hold
the module in place as the screws are removed, to avoid strain on the
ribbon cables.
TIP The MV SMC Flex must use firmware release 3.006 or later. This User Manual
pertains to units with firmware released 4.xxx (or later).