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Corp. 1244-L9
INTELLIGENT POWER MODULE (IPM) PROTECTION (H5)
The IPM module, which is an integrated part of the outdoor control, protects the system from the following conditions:
*
High ambient temperatures
*
Loss of cooling to the heat sink
* Low
voltage
*
Loose heat sink to control board
An inverter drive (VFD) works by taking AC mains (single or three phase) and first rectifying it into DC. The DC is usually
smoothed with capacitors and often a DC choke before it is connected to a network of power transistors to turn it into three
phases for the motor.
The network of power transistors of a small Inverter drive is actually one intelligent power module or inverter power module
(IPM) and includes its own basic control circuits and protection from overheating and low voltage conditions.
The IPM inverts the DC into AC, hence the term
inverter
. The control method is known as for pulse width modulation (PWM).
This means the DC is switched on and off very quickly (chopped) by the transistor switches.
POWER FACTOR CORRECTION (PFC) PROTECTION (HC)
The PFC module which is an integrated part of the outdoor control will monitor the DC bus for high, low and abnormal voltage
conditions. If any of these conditions are detected the PFC function and compressor will stopped. The appropriate error code
will be displayed on the indoor or outdoor units or both. Once the detected condition is corrected, the system will resume
normal operations after the minimum 3-minute compressor delay is met. In the case of either an abnormal condition or a high
/ low voltage condition that has occurred three consecutive times, the system will need to be manually powered off (outdoor
unit disconnect or main breaker panel) and back on to continue operation.
NOTE —
HC
for example is an error code for a PFC module failure. Codes that are generated by the PFC module when
monitor voltage conditions are for example H4, U3, PL, etc.
COMPRESSOR OVER-CURRENT PROTECTION (P5)
The compressor current is continuously monitored. Based on the current draw (amps) the microprocessor will signal the
compressor to increase, maintain drop or cycle
OFF
the compressor. Over current condition can result from any of the
following:
*
High outdoor ambient temperatures
*
Locked rotor on the compressor
*
Outdoor air restriction or blockage
*
Restriction or blockage in refrigeration system
COMPRESSOR OVER-LOAD PROTECTION (OVC-COM) (H3)
If temperature detected by the overload sensor exceeds 239ºF (115ºC), the compressor will stop. The outdoor fan will stop
after a delay of 30 seconds. Once the compressor temperature drops below 204ºF (95ºC), the compressor overload
protection feature will reset and the system will resume normal operations.
OUTDOOR COIL HIGH TEMPERATURE PROTECTION (FA)
Outdoor coil for air conditioning operation and indoor coil for heating operation (Heat pump only).
When the coil
temperature (outdoor coil for air conditioning and indoor coil for heating) drops below 124°F ( 51°C) and the compressor has
been
OFF
for more than 3 minutes, the system will resume normal operation. The coil sensor (outdoor coil sensor for air
conditioning and indoor coil sensor for heating) is continuously monitoring the coil temperature and communicates this to the
microprocessor. The microprocessor takes these measurements and changes the frequency of the compressor to meet the
system load. If the coil temperature increases into the ranges noted in the above chart, the microprocessor will adjust the
frequency or cycle the compressor
OFF
.
Indoor Fan Operation
When compressor is cycled
OFF
, the indoor fan will continue to run at a preset speed in air conditioning or in heating it will
cycle
OFF
60 seconds after compressor.
