User Manual

Rockwell Automation Publication 193-UM002I-EN-P - December 2011 271
Appendix D
Two-Speed Applications
Introduction
The E3 Plus Overload Relay Series B and later provides 2-Speed FLA Set,
Parameter 88, for use in two-speed motor applications. This appendix provides
overview and guidance on various methods that can be employed to protect two-
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 two-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 2-Spd Net
Enable, Parameter 87, is set to “1” or “Enable”, the overload function’s TCU
calculation is based on the 2-Speed FLA Set, Parameter 88, setting when Out B is
commanded closed.