Danfoss AK-CC 750A User Manual page 79

Desynchronisation of valve openings
To achieve even loading on the compressors, a desynchronising
function has been built in which ensures that the times for sole-
noid valve opening are displaced.
Within the same controller
If several valves are used on the same controller, the opening
times are displaced in relation to one another. For example, if two
valves are used, the opening of these is displaced in relation to
one another by half a period.
Between controller
Displacement of the opening of the solenoid valves takes place
on the basis of the controllers' address settings. If a period time of
300 seconds (factory default) is used, the opening of the solenoid
valves for the A section will be displaced by 15 seconds x last digit
in the address setting, e.g.:
Addresses 0, 10, 20: are shifted by 0 seconds
Addresses 1, 11, 21: are shifted by 15 seconds, etc.
This desynchronisation between controller takes place during
start-up and once a day at around midnight, 00:00
Address / Section
10 / A
10 / B
11 / A
11 / B
12 / A
12 / B
22 / A
22 / B
Thermostat sensor
Individual thermostat
When individual thermostat control is used in every section, the
temperature is controlled on the basis of the air temperature sen-
sors S3, S4 or both.
Definition of the thermostat temperature takes place using one
setting, which is based on the S4 value. With a setting of 100%,
only the S4 measurement will be used. With a setting of 0%, only
S3 will be used. With a value between 0 and 100%, both measure-
ments will be used.
AK-CC 750A RS8HP102 © Danfoss 2018-09
If AKV (stepper) valves are used, at least one sensor must always
be used in every section, irrespective of the choice of thermostat
function. This measurement is used by the injection function for
the superheat controller.
Common thermostat
When a common thermostat is used, the thermostat settings in
section A are used to control the air temperature.
The thermostat temperature can be either a weighting of the
S3 and S4 sensors in section A, as described for the individual
thermostat. This will typically be used in cold storage rooms and
freezer rooms in which several evaporators are controlled accord-
ing to a common temperature.
Alternatively, the thermostat temperature can be a minimum
value, a maximum value or an average value of all S3 or S4 sen-
sors for the refrigeration sections used. This will typically be used
where one solenoid valve is used for several appliance sections
and where it is necessary to ensure that the thermostat is taking
into account the temperature in all sections.
Min. S4 /
Max. S4 /
S4 average
Min. S3 /
Max. S3 /
S3 average
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