Owner manual

27
Status Lights (for units with LEDs)
During normal operation, both the green LED and the yellow LED are illuminated. The green LED
indicates that control power is applied to the monitor board. The yellow LED indicates that the fault
relay is energized.
If the green LED is not illuminated, possible causes include:
♦ The source of control power is shut off.
♦ A fuse or other protective device external to the MotorGuard has interrupted control
power. There may be a short circuit, ground fault, or overload condition in the
MotorGuard or in some other wiring or equipment connected to the same source of
control power.
♦ A primary or secondary control power transformer fuse has blown in the MotorGuard.
There is probably a short circuit, ground fault, or overload condition in the MotorGuard.
Check for evidence of damaged, burned, or overheated wiring or components.
♦ Check the following items:
Control circuit wiring
Control circuit transformer
Cooling fan
Monitor board
If the yellow LED is not illuminated, the monitor board has detected one or more of the following
MotorGuard output fault conditions:
♦ The output waveform dv/dt exceeds the rated maximum (1,000 V/μs for 480 V units and
1500 V/μs for 600 V units).
♦ The output waveform peak voltage exceeds the selected maximum (1000 V for 480 V units
and 1500 V for 600 V units).
The following conditions can cause MotorGuard output faults:
♦ Blown R-C power circuit fuses
If fuses are blown, check for damaged components or wiring in the R-C power circuit.
Check for discolored or burned components and deformed or leaking capacitors.
Damaged components can be caused by overheating – check fan. Components can also
be damaged if the VFD has been operating improperly or out of range for proper
MotorGuard performance.
♦ Damaged R-L-C power circuit components
Components can be damaged without blowing fuses. See above.
♦ VFD operating improperly or out of range for proper MotorGuard performance
♦ Problem with VFD or motor
♦ Loose power circuit wiring connections