Rockwell Automation 1560E SMC Flex Smart Motor Controller - Manual (Page 125)

Troubleshooting 9-7
The most straightforward means of checking the feedback circuits is to
perform the "snubber and resistor testing" procedure, found on page 9-27.
Another possible test involves measuring the feedback voltages at the
interface board (see Figure 3.2). 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 as
follows (check all three phases):
Table 9.F – Voltage Feedback Measurements
System Voltage
(V
LL
)
Feedback Voltage
System Voltage
(V
LL
)
Feedback Voltage
1000 1.9 – 2.1 4160 1.5 – 1.7
1300 2.4 – 2.6 4800 1.0 – 1.2
1500 2.8 – 3.0 5500 1.1 – 1.3
2400 1.8 – 2.0 6600 1.4 – 1.5
3300 1.2 – 1.4 6900 1.5 – 1.6
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.
Voltage Feedback Circuit
Tests