User guide

14 Rockwell Automation Publication 1560E-UM051F-EN-P - June 2013
Chapter 1 Product Overview
Figure 13 illustrates the required PTC sensor characteristics, per IEC-34-11-2.
Figure 13 - PTC Sensor Characteristics per IEC-34-11-2
PTC Trip
The MV SMC Flex will trip with a PTC indication if:
• No other fault currently exists
• PTC protection is enabled
• The resistance across terminals 23 and 24 is either greater than the relay’s
response resistance or less than the short-circuit trip resistance.
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 82).
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.
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