Rockwell Automation 7763 Medium Voltage OneGear SMC Flex Motor Controller (10-15 kV) - Manual (Page 28)

28 Rockwell Automation Publication 7760-UM001D-EN-P - October 2014
Chapter 1 Product Overview
Protection and Diagnostics The MV SMC Flex controller is capable of providing the following protective
and diagnostic features:
Overload
The MV SMC Flex controller meets applicable requirements as a motor overload
protection device. Thermal memory provides added protection and is
maintained even when control power is removed. The built-in overload
algorithm controls the value stored in Parameter 12, Motor Thermal Usage (see
Chapter 3, Programming). An Overload Fault will occur when this value reaches
100%. The parameters below provide application flexibility and easy setup.
Table 4 - Overload Parameters
Notes:
1. If the MV SMC Flex is used to control a multi-speed motor, or more than
one motor, the Overload Class parameter must be programmed to "OFF"
and separate overload relays must be supplied for each speed/motor.
2. Automatic reset of an overload fault requires the start input to be cycled in
a 2-wire control scheme.
3. The trip rating is 117% of the programmed FLC.
Figure 14 and Figure 15 provide the overload trip curves for the available trip
classes.
Separate protection relay c/w instantaneous overcurrent protection is required
when used with vacuum breakers.
Parameter Range
Overload Class Disable, 10, 15, 20, 30
Overload Reset Manual...Auto
Motor FLC 1.0...2200 A
Service Factor 0.01...1.99
IMPORTANT During slow speed operations, current waveforms exhibit non-sinusoidal
characteristics. These non-sinusoidal characteristics inhibit the controller's
current-measurement capability. To compensate for additional motor heating
that may result, the controller uses motor thermal modeling, which increments
motor thermal usage. This compensation takes place when the Preset Slow
Speed option is used.