Rockwell Automation 193-EC4 EC4 Current Monitoring Relay User Manual - Manual (Page 150)

Rockwell Automation Publication 193-UM011A-EN-P - September 2010 151
Appendix
D
Two-Speed Applications
Introduction The Series B and later EC4 Current Monitoring Relay provides Parameter 88,
2-Speed FLA Set, for use in two-speed motor applications. This appendix
provides overview and guidance on the various methods the E3 Plus can be
employed to protect 2-speed motors.
External Control
Applications For applications in which the two-speed starter control is accomplished
externally from the E3 Plus outputs, an auxiliary contact associated with the high
speed contactor is wired to one of the E3 Plus inputs. The corresponding input
assignment parameter (83 - 86) is set to “2-Speed”. The overload function’s
thermal capacity utilized (TCU) calculation is based on the Parameter 88 setting
when the 2-speed assigned input is asserted.
Output Control Applications For applications that use the integral outputs of the E3 Plus, Out A is used to
control the low speed contactor and Out B is used to control the high speed
contactor. Control can be accomplished through commands transmitted by the
network master or internal DeviceLogix function blocks. When Parameter 87,
2-Spd Net Enable, is set to “1” or “Enable”, the overload function’s thermal
capacity utilized (TCU) calculation is based on the Parameter 88 setting when
Out B is commanded closed.