124 Capacity controller RS8HE202 © Danfoss 2017-07 AK-PC 781A
Main switch
The main switch is used to stop and start the controlling function.
The switch-over has 2 positions:
- Normal controlling state (Setting = ON)
- Control stopped. (Setting = OFF)
In addition, one can also choose to use a digital input as an
external main switch.
If the switch-over or the external main switch is set at OFF, all the
control’s functions are inactive and an alarm is generated to draw
attention to this – all other alarms cease.
External switch for stopping compressors
The switch will stop the compressors, but all other functions will
continue to be regulated.
Refrigerant
Before regulation can be commenced, the refrigerant must be
defined.
You can select one of the following refrigerants:
1 R12 12 R142b 23 R410A 34 R427A
2 R22 13 User defined 24 R170 35 R438A
3 R134a 14 R32 25 R290 36 R513A
4 R502 15 R227 26 R600 37 R407F
5 R717 16 R401A 27 R600a 38 R1234ze
6 R13 17 R507 28 R744 39 R1234yf
7 R13b1 18 R402A 29 R1270 40 R448A
8 R23 19 R404A 30 R417A 41 R449A
9 R500 20 R407C 31 R422A 42 R452A
10 R503 21 R407A 32 R413A
11 R114 22 R407B 33 R422D
The refrigerant can only be changed if the “Main switch” is set at
“stopped control”.
A set glide value for all refrigerants in the R400 series.
Warning: Incorrect selection of refrigerant can cause damage to
the compressor.
Sensor failure
If lack of signal from one of the connected temperature sensors or
pressure transmitters is registered an alarm will be given.
• When there is a P0 error regulation will continue with 50% cut-in
capacity during day operation and 25% cut-in capacity during
night operation – but minimum one step.
• When there is a Pc error 100% condenser capacity will be cut in,
but the compressor regulation will remain normal.
• When there is an error on the Sd sensor the safety monitoring of
the discharge gas temperature will be discontinued.
• When there is an error on the Ss sensor the monitoring of the
superheat on the suction line will be discontinued.
• When there is an error on the outdoor temperature sensor
Sc3 the “FDD” function will cease. Regulation with variable
condensing pressure reference cannot either be carried out.
Instead you use the PC ref. min. value as reference.
• In the event of Sgc faults, further adjustments are carried out
using the Shp signal.
Note: An incorrect sensor must be in order for 10 minutes before
the sensor alarm deactivates.
Sensor calibration:
The input signal from all connected sensors can be corrected. A
correction will only be necessary if the sensor cable is long and
has a small cross-sectional area. All displays and functions will
reflect the corrected value.
Clock function
The controller contains a clock function.
The clock function is used only to change between day/night.
The year, month, date, hour and minutes must be set.
In the event of a power failure, the time setting will be remembe-
red for at least 12 hours.
If the controller is connected to an installation with an AKA-
gateway or an AK system manager, this will automatically reset
the clock function.
Alarms and messages
In connection with the controller’s functions, there are a number
of alarms and messages that become visible in cases of fault or
erroneous operation.
Alarm history:
The controller contains an alarm history (log) that contains all
active alarms as well as the last 40 historical alarms. In the alarm
history you can see when the alarm began and when it stopped.
In addition, one can see the priority of each alarm as well as when
the alarm has been acknowledged and by which user.
Alarm priority:
Differentiation is made between important and not-so-important
information. The importance – or priority – is set for some alarms
whilst others can be changed voluntarily (this change can only
be done with attachment of AK-ST service tool software to the
system and settings must be made in each individual controller).
The setting decides which sorting / action must be carried out
when an alarm is sounded.
• “High” is the most important
• “Log only” is the lowest
• “Interrupted” results in no action
Alarm relay
One can also choose whether one requires an alarm output on
the controller as a local alarm indication. For this alarm relay it is
possible to define on which alarm priority it must react to – one
can choose between the following:
• “Non” – no alarm relay is used
• “High’ – Alarm relay is activated only with alarms with high
priority
• “Low - High’ – Alarm relay is activated only with alarms with “low”
priority, “medium” or “high” priority.
Miscellaneous
Safety disconnection signal
Unexpected disconnection of the compressor, condensation fan
or frequency convertor can result in unexpected temperature
increases in the system. If necessary, use the necessary safety
signals to ensure that the controller receives signals about discon-
nections.
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