Rockwell Automation 1560E SMC Flex Smart Motor Controller - Manual (Page 19)

Product Overview 1-9
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 4, Programming). An Overload Fault will
occur when this value reaches 100%. The parameters below provide
application flexibility and easy setup.
Parameter Range
Overload Class Off, 10, 15, 20, 30
Overload Reset Manual – Auto
Motor FLC 1.0 – 1000.0 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 compen-
sation takes place when the Preset Slow Speed option is used.
Notes:
1. The factory default setting for Overload Class, which is "OFF", disables
overload protection. An overload trip class and the motor's full-load
current rating must be programmed to enable overload protection.
2. 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.
3. Automatic reset of an overload fault requires the start input to be
cycled in a 2-wire control scheme.
4. The trip rating is 117% of the programmed FLC.
Figures 1.9 and 1.10 provide the overload trip curves for the available trip
classes.