Danfoss AK-CC 550B User Manual

8 Manual RS8GL302 © Danfoss 2016-03 AK-CC 550B
Control of two compressors (application 5)
The two compressors must be of the same size. When the control-
ler demands refrigeration it will rst cut in the compressor with
the shortest operating time. After the time delay the second
compressor will be cut in.
When the temperature has dropped to ”the middle of the dieren-
tial”, the compressor with the longest operation time will be cut
out.
The running compressor will continue until the temperature has
reached the cutout value. Then it will cut out. When the tempera-
ture again reaches the middle of the dierential, a compressor will
again be started.
If one compressor cannot maintain the temperature within the
dierential, the second compressor will also be started.
If one of the compressors has run on its own for two hours, the
compressors will be changed over so that operational time is bal-
anced.
The two compressors must be of a type that can start up against a
high pressure.
The compressors’s settings for ”Min On time” and ”Min O time”
will always have top priority during normal regulation. But if one
of the override functions is activated, the ”Min On time” will be
disregarded.
Railheat
It is possible to pulse-control the power to the rail heat in order to
save energy. Pulse control can either be controlled according to
day/night load or dew point.
Pulse control according to day and night
Various ON periods can be set for day and night operation.
A period time is set as well as the percentage part of the period in
which the rail heat is ON.
Pulse control according to dew point
In order to use this function a system manager of the type AK-SM
is required which can measure dew point and distribute the cur-
rent dew point to the appliance controllers. For this the rail heat’s
ON period is controlled from the current dew point.
Two dew point values are set in the appliance control:
• One where the eect must be max. i.e.100%. (o87)
• One where the eect must be min. (o86).
At a dew point which is equal to or lower than the value in 086,
the eect will be the value indicated in o88.
In the area between the two dew point values the controller will
manage the power to be supplied to the rail heat.
During defrosting
During defrosting the rail heat will always be 100% ON.
Dew point
Rail heat

Danfoss AK-CC 550B Specifications

General

Brand	Danfoss
Model	AK-CC 550B
Category	Controller
Language	English