Functions
Voltage protection
The voltage protection ensures that the compressor motor is operating within safe voltage ranges. If the power
supply voltage gets outside the specified high/low voltage cut-out ranges, the compressor is cut-out or restricted
from starting. Normal compressor operation is resumed when the power supply voltage is back in the area between
the high voltage cut-out limit and the low voltage cut-in limit.
Figure 4: Voltage protection
High voltage limit
Low voltage cut-in
limit (compressor start)
Low voltage cut-out
limit (alarm and
compressor stop)
Danf
oss
80G8366
Compressor protection
Compressor protection feature protects compressor from short ON and OFF cycles by securing minimum run and
stop time. This would allow the refrigeration system to stabilize before starting the compressor again and also avoid
the chances of too many compressor cycles.
Figure 5: Compressor protection
Po
w
er t
o c
ompr
essor
min run time
ON
OFF
CUT-IN
CUT-OFF
min stop time
time
time
Temper
atur
e
Danf
oss
80G8375
Compressor protection against high condensing temperature
If the condenser is blocking up with dirt and thereby reaches a too high condensing temperature, the controller will
give the user early warning through condenser alarm and if temperature rises further, it will switch the compressor
OFF. If the temperature measured by the condenser sensor (Sc) is reaching the set “pre-alarm limit” an alarm is
raised, but no further action is taken. This is used to indicate to the user that something is wrong with the
condenser. Often the reason is that that the air flow to the condenser is restricted (dirt) or because the condenser
fan is broken.
The alarm will reset if the condenser temperature drops back by 5 °C. If the measured condenser temperature
continues to increase and reaches the set “Block limit” the compressor is stopped, and it is restricted from starting
again until the alarm is reset manually. The alarm can be reset manually by setting the parameter r12 Main switch to
OFF position and back to ON position or by powering the controller down.
Electronic refrigeration control, type ERC 21X
© Danfoss | Climate Solutions | 2023.01
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