22
RLC-SVD05A-EN
Variable Speed Fan Control - RTAC Only
Inverter Fault Input
The Variable Speed Condenser Fan Inverter provides a fault indication to the MP
through an optically isolated darlington transistor circuit. The transistor is off
when the inverter is un-powered or in the fault state, and is on at all times during
normal operation. A fault signal is sent by the inverter if it has gone through a
self shutdown or if the output frequency of the inverter is limited to less than 50%
of the signal speed commanded by the MP. Upon receipt of the fault signal (high
voltage at fault input terminals), the MP attempts to reset the fault by sending a 0
PWM command to the inverter for a total of 5 seconds. The fault signal again
checks and will be repeated if still in fault. If four faults are detected within 1
minute of each other, the power to the inverter cycles off for 30 seconds (through
contactor control) and then re-powered. If the fault still remains or occurs again
within 1 minute, a diagnostic is called out, the MP shuts off the Inverter, and
attempts to run the remaining constant speed fans using the normal constant
speed Fan Control Algorithm. When 2 inverters are configured on a circuit, the
fault responses are directed to both of the inverters on that circuit. The only
exception is that the diagnostic specifies which inverter of the pair reported the
fault.
Troubleshooting the Inverter
The purpose of this troubleshooting section is to help technicians determine if
the variable speed fan inverter, the compressor module, the fan contactor, the fan
motor, or the interconnecting wiring is faulty.
WARNING
Live Electrical
Components!
During installation, testing, servicing and troubleshooting of this product, it may
be necessary to work with live electrical components. Have a qualified licensed
electrician or other individual who has been properly trained in handling live
electrical components perform these tasks. Failure to follow all electrical safety
precautions when exposed to live electrical components could result in death or
serious injury.
WARNING
Hazardous
Voltage!
The VFD's have large capacitors that can store high voltage even when
denergized. Once denergized the capacitor may take 1 minute to completely
discharge. Always wait for at least 1 minute before servicing the VFD to insure
the capacitors are completely discharged. The green status LED will turn off
when the capacitor has discharged. Failure to follow these instructions could
result in death or serious injury.
Status Indication on the VFD
Two LED’s are provided for drive status indication. One green Power LED lights
when power is applied to the unit. The other red Alarm LED lights in the event of
a pending overload or flashes in the event of a fault for the first minute after the
fault occurs.
Power On LED.
This green LED is illuminated any time that more than 50 VDC is
present on the DC Bus Capacitors. Typically when power is removed from the
