Rockwell Automation 7703E Medium Voltage SMC OEM Components - 10-15 kV - Manual (Page 35)

Rockwell Automation Publication 7703E-IN001E-EN-P - July 2014 35
Chapter
5
Main and Bypass Switching Device Installation
Introduction The MV SMC components are designed for intermittent starting duty. A bypass
contactor or circuit breaker must be used to bypass the PowerBrick assemblies
once the motor is at full speed.
Main Contactor or Circuit
Breaker A line switch is required in order to isolate the power stacks from line voltage.
• If a line contactor is used, suitable short-circuit protection must be
provided in compliance with relevant standards and/or local codes (refer
to Section 2).
• If a circuit breaker is used for the line switch, it must be rated to handle
normal load and short-circuit conditions.
Bypass Contactor or Circuit
Breaker A bypass contactor or circuit breaker must be used in the SMC configuration to
bypass the SCRs once the motor is up to speed. The bypass must have an opening
time of 100 ms or less.
ATTENTION: A bypass contactor or circuit breaker must be installed to
complete the SMC configuration. SCRs are not rated for continuous duty. The
duty cycle is limited to 60 seconds per hour. This can be a combination of
starting and stopping cycles that does not exceed 30 seconds per cycle. Failure
to install a bypass contactor or circuit breaker may result in damage to
components from overheating.