Rockwell Automation MV SMC Flex Motor Controller (for Series K or later) - Manual (Page 18)

8 Rockwell Automation Publication 1560E-UM051F-EN-P - June 2013
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
(Refer to
Chapter 4, Programming ). An Overload Fault will occur when this
value reaches 100%. The parameters below provide application flexibility and
easy setup.
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 9 and Figure 10 provide the overload trip curves for the available trip
classes.
Parameter Range
Overload Class Disable, 10, 15, 20, 30
Overload Reset Manual – Auto
Motor FLC 10 – 2200 amps
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.