Danfoss AK-PC 351 - Fan Control and Safety; Fan Mode and Control Type; Suction Safety Limits and Alarms; Condenser and Temperature Safety Limits

AK-PC 351 User Guide RS8GZ302 © Danfoss 2015-06 13
Fan mode Conguration of fans:
Fan speed & DO: Speed controled fans via AO2 and start/stop via DO output.
Fan speed: Speed controlled fans via AO2
4 Fan step: step-by-step . Start/stop via 4 pcs. DO outputs
3 Fan step: step-by-step . Start/stop via 3 pcs. DO outputs
2 Fan step: step-by-step . Start/stop via 2 pcs. DO outputs
1 Fan step: step-by-step . Start/stop via 1 pcs. DO outputs
Not used
For step-by-step connection, the fans cut in and out sequentially (e.g. 123-321).
DO-demand
AO-demand
Fac: Fan speed&DO
Control type Normally, PI-regulation is used, but this can be changed to a P-regulation if the design of the
system necessitates this.
• PI Ctrl: Regulation is carried out here with as little deviation between the reference and
measurement as possible.
• P-band ctrl: Capacity is cut in here after proportional regulation.
P / PI
Fac: PI
VSD Start speed Set the start speed of the frequency converter here.
The value must be higher than the VSD min. speed value.
Min: 0%
Max: 40%
Fac: 20%
VSD Min speed Set the minimum speed of the frequency converter here.
If lower capacity is required, this minimum speed should be maintained untill the required
capacity reach 0%. Hereafter all fans stops completely
Min: 0%
Max: 40%
Fac: 10%
Fan status Fan status
Fan speed Here a reading of the actually condenser fan capacity in % (speed control)
Fan 1 status The status of Step 1 (step 1 or relay for frequency transformer) is indicated here
Fan 2..... The status of Step 2, 3, etc. is indicated here
Safety monitoring
Po/S4 Min limit Safety limits for min. Po
If a low value is registered, all compressors will cut out
Min: -120°C (-1.0 bar)
Max: 30°C (159 bar)
Fac: -40°C (0.5 bar)
Po/S4 Max alarm Alarm limit for high Po
If a high value is registered, an alarm will be generated
Min: -30°C (-1.0 bar)
Max: 100°C (159 bar)
Fac: 100°C (5.0 bar)
Po/S4 Max delay Delay time for issuing a Po max. alarm
Min: 0 min.
Max: 240 min.
Fac: 5 min.
Pc max limit Safety limit for max. Pc
If Pc exceeds the value set here minus 3 K, the entire condenser capacity will cut in,
and compressor capacity will be reduced by 1/3 for every 30 seconds.
If Pc exceeds the threshold value, the entire compressor capacity will immediately cut out,
and an alarm will be generated when the delay time expires.
Min: -1 bar
Max: 159 bar
Fac: 40 bar
Tc Max limit Safety limit for max. Tc
The setting for PC max. limit, converted to temperature, can be read here.
-
S7 max limit Safety limit for S7
If S7 exceeds the value set here minus 3 K, the entire condenser capacity will cut in,
and compressor capacity will be reduced by 1/3 for every 30 seconds.
If S7 exceeds the threshold value, the entire compressor capacity will immediately cut out,
and an alarm will be generated when the delay time expires.
Min: -50°C
Max: 100°C
Fac: 100°C
Pc/S7 Max delay Time delay for Pc max. alarm
The alarm will only be generated when the time delay has elapsed.
Min: 0 min.
Max: 240 min.
Fac: 0 min.
Safety restart time Delayed start-up following safety cut-out
If a safety cut-out has occurred due to “Pc max. limit” or “Po min. limit”,
the compressors must be kept stopped for a dened period of time. The amount of
time can be set here.
Min: 0 min.
Max: 60 min.
Fac: 1 min.
Sensor alarm reset Reset alarm after sensor error
When a sensor error has occurred, an O.K. signal must be registered within a specied
number of minutes before the controller resets the alarm. The regulation will be resumed
as soon as the sensor signal is O.K.
Min: 0 min.
Max: 30 min.
Fac: 10 min.