Allen-Bradley SMC-50, User Manual

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Rockwell Automation Publication 1560F-UM001A-EN-P - June 2019 31
Product Overview Chapter 1
Open Gate
An open-gate fault indicates that improper SCR firing, typically caused by an
open SCR gate or driver system, has been detected on one of the power poles.
Before the controller shuts down, it will attempt to start the motor a total of three
times (or as programmed in Parameter 133).
An open gate is detected when the module sends a gate signal to the SCRs but
does not detect that they turned on. SCR turn-on is detected when the voltage
across the leg (L-T) collapses. The Open Gate detection is active during starting
or stopping only.
Line Faults with Phase Indication
The SMC-50 control module continually monitors line conditions for abnormal
factors. Pre-start protection includes:
• Line Fault (with phase indication)
– Line voltage loss
– Missing load connection
– Shorted SCR
Running protection includes:
• Line Fault (no phase indication)
– Line voltage loss
– Missing load connection
Phase reversal protection
(3)
can be toggled either ON or OFF.
The SMC-50 control module can individually identify and provide a Fault and
or Alarm if a power line loss occurs on any phase.
The Line Loss Fault is enabled or disabled using the Line Loss bit in the Starter
Fault Enable, Parameter 136. In addition, a Line Loss Alarm can be enabled or
disabled using the Line Loss bit in the Starter Alarm Enable, Parameter 137.
(3) Phase reversal protection is functional only at pre-start.
TIP
Phase A, B, or C loss = Fault Code 1, 2, or 3 respectively. There are no line loss
Fault Parameters to configure.
TIP
If Line Loss is disabled, consider enabling the Undervoltage Fault to limit
potential motor damage caused by phase loss.