Danfoss AK-PC 551 User Manual page 13

Sc3 offset
Min. reference
Max. reference
Heat recocery SP
Heat rec. ramp down
Capacity limit night
Gain factor Kp
Integration time Tn
Fan configuration
Control sensor
Reference mode
Capacity ctrl. mode
No. of fans
Control type
VSD Start speed
VSD Min speed
VSD Start via DO
Monitor fan safety
Fan at comp. OFF
Heat recovery via DI
AK-PC 551
Temperature offset for regulation with fluid reference.
Regulation reference = Sc3 measurement + Sc3 offset
Set the lowest permissible regulation reference here
Set the highest permissible regulation reference here
Temperature set point for heat recovery function (only when the function is selected during
configuration)
Ramp-down of regulation reference after heat recovery
Set how quickly the reference for condenser pressure should be made after heat recovery
ends. Enter the change in degrees Kelvin per minute.
Capacity limitation at night
The speed of the fans can be limited here when regulating using speed control.
During step-by-step activation, the start of the step-by-step process is limited.
Amplification factor for PI regulation
If the Kp value is lowered, regulation runs more smoothly
Integration time for PI regulation
If the Tn value is increased, regulation will run more smoothly
Configuration of fans
Selection of regulation sensor:
• Pc pressure transmitter
• S7 media temperature sensor (Pc must be installed for safety monitoring)
Set the reference for regulation here
• Fixed reference; the reference here will be the defined set point
• Variable reference; the reference here will follow the outside temperature, which is meas-
ured with Sc3.
Set the way in which the fans should be controlled here
• Variable; the fans are controlled by a 0-10 V signal from an analogue output. If it is defined in
"VSD Start via DO", a relay will be able to start and stop the frequency converter.
• Step; on/off control of fans will be via relays
• Variable + step. The signals are parallel, so external wiring can switch over to step, e.g. if the
frequency converter fails.
Enter the number of fans here.
For step-by-step activation, select the number of relays. The relays will cut in/out sequentially,
e.g. 123-321.
For speed control, select 1 or higher. No relay is reserved, but the setting makes it possible to
define the monitoring of fans.
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.
Set the start value of the frequency converter here.
The value must be higher than the VSD min. speed value.
Set the minimum speed of the frequency converter here.
If lower capacity is required, this minimum speed should be maintained all the way down to
0% capacity. At 0% capacity, the system stops completely.
Define whether a relay should be connected to the frequency converter start/stop function
here:
• No: no relay
• Yes: the relay pulls in when the frequency converter needs to be in operation.
Define whether safety monitoring of the condenser fans should be performed.
• None: no monitoring
• Individual: a DI input is reserved for each fan
• Common: a DI input that is common for all condenser fans is reserved .
Select the way in which the fans should be controlled when all the compressors have
stopped.
• Normal regulation: Fans to be controlled in compliance with normal regulation.
• Energy-optimised: Fan capacity will be maintained at between 0 and 49% in a p-band of
5-15 K above reference.
Define whether a heat recovery cycle should be started with a signal on a DI input here.
• No: No function
• Yes: A DI input is reserved. When a signal is registered, the heat recovery function reference
will become active.
User Guide RS8GY302 © Danfoss 2015-06
Min: 0 K
Max: 20 K
Fac: 6 K
Min: -25°C (-1.0 bar)
Max: 100°C (159 bar)
Fac: 10°C (5.0 bar)
Min: -25°C (-1.0 bar)
Max: 100°C (159 bar)
Fac: 50°C (35.0 bar)
Min: 20°C (-1.0 bar)
Max: 90°C (159 bar)
Fac: 50°C (30.0 bar)
Min: 0,1 K
Max: 100 K
Fac: 1 K
Min: 0 %
Max: 100%
Fac: 100%
Min: 1
Max: 30
Fac: 10
Min: 30 s
Max: 240 s
Fac: 180 s
AI-demand
Pc / S7
Fac: Pc
AI-demand
Setpoint / Floating
Fac: Setpoint
AO-demand
Step / Speed
Fac: Step
DO-demand
Min: 0
Max: 8
Fac: 0
P / PI
Fac: PI
Min: 0%
Max: 40%
Fac: 20%
Min: 0%
Max: 40%
Fac: 10%
DO-demand
Yes / No
Fac: No
DI-demand
Common /Indi-
vidual
Fac: None
Normal/Optimized
Fac.: Normal
DI-demand
Yes / No
Fac: No
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