Chapter 6—Motor Protection
Power Xpert C445 Global Motor Management Relay
MN042003EN—January 2019
www.eaton.com
115
The thermal overload is designed to protect the motor from
overheating caused by excessive current. If the motor is
overloaded, the current level may rise above motor FLA and
heats the motor.
The FLA sets the trip threshold and the trip class (5 to 40) is
set with Overload Trip Class.
The trip class settings of the C445 motor management relay
are suitable for both normal start-ups as well as for heavy
duty starting. The Trip Class setting enables a particular
tripping characteristic to be selected. These are the
following:
CAUTION
The motor, the wiring diameter and the switching device(s)
must be suitable for the selected Trip Class.
CAUTION
The current-dependent protective device must be selected
so that not only is the motor current monitored but the
blocked motor is switched OFF within the temperature rise
time.
The thermal memory and the reset inhibit time are saved to
the non-volatile memory. Cycling power on the device will
NOT clear the thermal Fault Trip nor reset the thermal
capacity stored in non-volatile memory. These values are
reloaded when the device boots and the timer is restarted at
the full reset time. This means if the 3 minute inhibit timer
has been running for two minutes, cycling power will require
the user to wait the full three minutes before a reset can
clear the overload fault.
Note:
The trip curves are based on a 115% Service
Factor rating.
