Danfoss ADAP-KOOL AK-HP 780 Design Manual page 89

Monitoring of max. discharge pressure (Pd)
The function cuts out compressor steps one by one if the
discharge pressure becomes higher than permitted. The cutout
limit can be defined in the range from –30 to +100°C.
The discharge pressure is measured with pressure transmitter Pd_.
The function takes effect at a value which is 3 K below the set
value. At this time 33% of the compressor capacity is cut out
(but min. one step). This is repeated every 30 seconds. The alarm
function is activated.
If the temperature (pressure) rises to the set limit value, the
following will happen:
- all compressor steps will immediately be cut out
The alarm will be cancelled and renewed cutin of compressor
steps is permitted when the following conditions are met:
- the temperature (pressure) falls to 3 K below the limit value
- the time delay for restart has been passed.
Delay of Pd max alarms
It is possible to delay the "Pd max alarm" message.
The controller will still disconnect the compressors, but the send-
ing of the alarm itself is delayed.
Time delay
There is a joint time delay for "Monitoring of max. discharge gas
temperature" and "Min. suction pressure".
After a cutout, regulation cannot be recommenced until the time
delay has been passed.
The time delay starts when the Sd temperature has again dropped
to 10 K below the limit value or P0 has risen above the P0 min.
value.
Alarm for too high suction pressure
An alarm limit can be set which will become effective when the
suction pressure becomes too high. An alarm will be transmitted
when the set time delay has been passed. The regulation
continues unchanged.
AK-HP 780 Heat pump controller RS8GF202 © Danfoss 2015-08 89