TCI KMG - Manual (Page 20)

20
Power Wiring
The conduit and wiring from the output of the variable frequency drive to the motor must be routed to
the MotorGuard and then to the motor. When selecting a mounting location for the MotorGuard, plan
for the routing of the power wiring.
Control Wiring (for units with boards)
Control Power
The MotorGuard requires 120 VAC single-phase power for the monitor board and cooling fan. The
control power source must be ensured to be energized whenever the variable frequency drive is
operating. A control power transformer is provided in the MotorGuard to allow control power to be
obtained from the three-phase source that provides input power to the VFD. Fuses are provided on the
control transformer, but the wires connecting control power to the MotorGuard will need to be
appropriately protected at the power source.
Control Power VA Requirement
Refer to the drawings furnished with your MotorGuard to determine the control power VA required.
Fault Alarm Contact
The fault alarm relay is energized when control power is applied to the MotorGuard and the output
waveform dv/dt and peak voltage are within specified limits. If the dv/dt or peak voltage limits are
exceeded, the fault relay is de-energized. A set of form C contacts are provided for customer use.
Determine how the MotorGuard's performance alarm contact will be used. It may be connected to the
VFD external fault input or to some supervisory control or alarm annunciation equipment. A
MotorGuard fault alarm indicates that the MotorGuard is not providing adequate dv/dt and peak
voltage protection. If the drive operation continues during a fault condition, the motor or other
equipment may be damaged. To guard against damage, consider connecting the MotorGuard to
automatically shut down the drive if a fault occurs. The best alternative to shutting down the drive is to
provide an alarm to personnel who will promptly investigate the problem.
Optional Features
Additional wiring requirements may apply to MotorGuard units that are equipped with certain optional
features such as a space heater or 120 VAC control power supplied directly rather than through a
control power transformer. For instructions covering these additional requirements, refer to drawings
and/or other supplemental information furnished with the unit.