Danfoss AK-PC 520 User guide

User Guide

Capacity controller

AK-PC 520

ADAP-KOOL® Refrigeration control systems

Introduction

Application

The controller is used for capacity regulation of compressors or condensers in small refrigerating systems.

There are eight outputs and up to 4 compressors and 4 fans can be coupled.

Advantages

•Energy conservation during:

-Suction pressure optimisation (P0)

-Variable condensing pressure (Pc)

•Patented neutral zone regulation

•Many possible combinations for compressor constellations

•Sequential or cyclic operation

•Possibility of suction pressure optimisation via the data communication

Regulation

Regulation is based on signals from one pressure transmitter for the compressor regulation and one pressure transmitter for the condenser regulation plus one temperature sensor for the air temperature before the condenser.

The two pressure transmitters can be replaced by two temperature sensors when regulation has to be carried out on brine systems.

•Pressure regulation P0 (pack)

•Temperature regulation Sx (chiller)

•Pressure regulation Pc (pack / chiller)

•Pressure regulation with variable reference Pc (Sc3)

Functions

•Relays for compressor and condenser regulation

•Voltage output for capacity regulation of condenser

•Status inputs. An interrupted signal indicates that the safety circuit has been activated and the respective circuit stopped

•Contact inputs for indication of alarms

•Contact inputs for displacement of references or for indication of alarms

•Alarm relay

•External start/stop of regulation

•Possibility of data communication

Operation

All operation takes place either via data communication or via connection of a display type EKA 164 or EKA 165.

Combinations

The controller has ten relay outputs two of which have been reserved for the alarm function and for the ”VLT start/stop” function.

For a start relays are reserved for compressor capacities starting from DO1, DO2, etc.

The next relay and the following will be for fans (max. 4 fans). Another solution could be that the fan speed is controlled via the analog output and a frequency converter.

Compressors and unloaders can be combined in various ways. Cf. survey on page 11.

Contents
Introduction........................................................................................................	2
Function...............................................................................................................	3
Survey of functions..........................................................................................	4
Operation...........................................................................................................	13
Menu survey.....................................................................................................	14
Connections......................................................................................................	18

Data......................................................................................................................	19
Ordering.............................................................................................................	19
Montage.............................................................................................................	19
Safety function.................................................................................................	20
Override..............................................................................................................	21
Appendix............................................................................................................	22

Manual RS8FK202 © Danfoss 12-2009

AK-PC 520

Function

Capacity regulation

The cut-in capacity is controlled by signals from the connected pressure transmitter/temperature sensor and the set reference. Outside the reference a neutral zone is set where the capacity will neither be cut in nor out.

Outside the neutral zone (in the hatched areas named +zone and -zone) the capacity will be cut in or out if the regulation registers a change of pressure “away” from the neutral zone. Cutin and cutout will take place with the set time delays.

If the pressure however “approaches” the neutral zone, the controller will make no changes of the cut-in capacity.

If regulation takes place outside the hatched area (named ++zone and --zone), changes of the cut-in capacity will occur somewhat faster than if it were in the hatched area.

Cutin of steps can be defined for either sequential or cyclic operation.

Sequential (first in - last out)

The relays are here cut in in sequence – first relay number 1, then 2, etc.

Cutout takes place in the opposite sequence, i.e. the last cut-in relay will be cut out first.

Cyclic (first in - first out)

The relays are coupled here so that the operating time of the individual relays will become equalised.

At each cutin the regulation scans the individual relays’ timer, cutting in the relay with least time on it.

At each cutout a similar thing happens. Here the relay is cut out that has most hours on the timer.

Rx = random relay h = number of hours

If capacity regulation is carried out on two compressors with one unloader each, the following function can be used:

Relays 1 and 3 are connected to the compressor motor. Relays 2 and 4 are connected to the unloaders.

Relays 1 and 3 will operate in such a way that the operating time for the two relays will become equalised.

C = compressor, L = Unloader

AK-PC 520

Survey of functions

The total function content is shown below – not all functions are present at the same time. The setting of o61 determines which functions are present.

The menu overview on page 14 shows the various functions and settings.

	Para-	Parameter by operation via
Function	meter	data communication
Normal display
If the two displays are mounted:		P0 °C or P0 b
P0 will be shown on EKA 165 (the one with buttons)		Pc °C or Pc b
Pc will be shown on EKA 163. Both readouts will be in temperature or in bar.
Compressor regulation reference		Compressor control
P0 setpoint	r23	P0Set Point °C / P0Set Point b
Regulation is based on the set value plus an offset, if applicable. An offset can be cre-
ated from night setback r13 and/or from a system units override function.
Offset	r13	Night offset
The set reference may be displaced with a fixed value when a signal is received at the
DI4 input or from the function "Night setback" (r27).
(Cf. also Definition of DI4 input).
Night setback (Displacement of P0)	r27	NightSetBack
OFF: No change of the reference
ON: Offset value forms part of the reference
Reference	r24	P0 ref. °C / P0 ref. b
The regulation reference is shown here
Set point limitation
With these settings the setpoint can only be set between the two values.
(This also apply if regulation with displacements of the reference).
Max. permissible setpoint value.	r25	P0RefMax °C / P0RefMax b
Min. permissible setpoint value.	r26	P0RefMin °C / P0RefMin b
Neutral zone	r01	Neutral zone
There is a neutral zone around the reference. See also page 3.
Correction of pressure measurement	r04	AdjustSensor
An offset adjustment of the registered pressure can be made.
Unit	r05
Here you can select whether the display is to indicate in SI units or US units.
0: SI (°C / bar)		(In AKM onlySI (bar and °C) is used,
1: US (°F / psig)		whatever the setting)
Start/stop of refrigeration	r12	Main Switch
With this setting the refrigeration can be started and stopped. Start/stop of refrigera-
tion may also be performed with an external contact function connected to the input
named “ON input”. (The input must be wired).
Condenser regulation reference		Condenser control
Pc setpoint	r28	PcSet Point °C / PcSet Point b
Regulation is based on the set value plus an offset, if applicable. An offset can be cre-
ated via the “r34” function and/or from a system units override function.
Offset	r34	PcRefOffset
The set reference may be displaced with a fixed value when a signal is received at the
DI5 input. (Cf. also Definition of DI5 input).
Pc reference variation. See also page 22	r33	Pc mode
Regulation with setting 1 (or 2 if the reference is to vary with the outdoor tempera-
ture) will give the best regulation if the system is in balance. But if a lot of condenser
steps are cut in and out and the compressor capacity often becomes low, it will be
necessary to select setting 3 instead (or 4, if there is regulation with the outdoor tem-
perature). (Settings 3 and 4 will generally be preferable if a Pc-offset at max. compres-
sor capacity can be accepted).
1: No change of the reference. Regulation based on set setpoint. And offset with the
DI5 function is allowed.
2: Outdoor temperature forms part of the reference. The outdoor temperature is
measured with Sc3. When the outdoor temperature drops one degree, the reference
is lowered one degree.
Here is offset with the DI5 function not allowed. At DI5 signal the reference will
change to the set setpoint.
Setting 1 and 2 operate with a PI regulation, but if the system is unstable and the PI
regulation not satisfactory the I element may be left out, so that the controller will be
with P regulation only.
3: As 1, but with P regulation (xp-band)
4: As 2, but with P regulation (xp-band)

AK-PC 520

Condenser reference	r29	Pc ref. °C / Pc ref. b
The regulation reference is shown here.
Set point limitation
With these settings the setpoint can only be set between the two values.
(This also applies to regulations where the Xp band lies above the reference).
Max. permissible setpoint value.	r30	PcRefMax °C / PcRefMax b

Min. permissible setpoint value.	r31	PcRefMin °C / PcRefMin b

Correction of pressure measurement	r32	AdjustSensor
An offset adjustment of the registered pressure can be made.
Dimensioning temperature Dim tm	r35	Dim tm K
The mean temperature difference across the condenser at maximum load (tm differ-
ence at max. load). This is the temperature difference between the air and condensing
temperature.
Dimensioning temperature Min tm	r56	Min tm K
The mean temperature difference across the condenser at the lowest relevant
compressor capacity (tm difference at min. load). This is the temperature difference
between the air and condensing temperature.
Reading your P0	r57 P0°C / P0 b
This is where you can see the actual pressure that is being measured by the pressure
transmitter.
The value is part of the regulation, since the regulation signal for capacity regulation
originates from the pressure transmitter.
The value is part of the frost protection regulation, since the regulation signal for
capacity regulation originates from the temperature sensor.
Reading your T0	r58	Cmp.CtrlSens
This is where you can see the actual pressure being measured by the sensor chosen
for capacity regulation (the sensor is defined in o81). The value is displayed in °C.
Compressor capacity		Compressor pack config.
Running time
To prevent frequent start/stop, values have to be set for how the relays are to cut in
and out.
Min. ON time for relays.	c01	Min.ON time
(The time is not used if the relay cuts an unloader in or out).
Min. time period between cutin of same relay.	c07	MinRecyTime
(The time is not used if the relay cuts an unloader in or out).
Setting for neutral zone regulation
Regulation band over the neutral zone	c10	+ Zone k / + Zone b

Time delay between step cut-ins in the regulation band over the neutral zone	c11	+ Zone m
Time delay between step cut-ins in the regulation band over the "+Zone band".	c12 + + Zone m

Regulation band under the neutral zone	c13	- Zone k / - Zone b

Time delay between step cut-outs in the regulation band under the neutral zone	c14	- Zone m

Time delay between step cut-outs in the regulation band under the "-Zone band"	c15	- - Zone m
Pump down limit	c33	PumpDownLim.
The factory setting for this function is OFF.
Activate by setting a value corresponding to pressure under the zone and over the P0
min. limit.
The function keeps the last capacity step going until the pressure comes down to the
pump down limit. When this value is reached the last compressor will cut out.
Do not reconnect capacity until the pressure is once more above the neutral zone.
Compressor configuration	c16	Compr mode
Here you set the predefined combination of number of compressors and any unload-
ers.
1 = One compressor, 2 = two compressors, 3 = three, 4 = four.
5 = One compressor + one unloader. 6 = One compressor + two unloaders.
For 7 to 8: See survey on page 11
Selection of coupling mode	c08	Step mode

1.Sequential: First relay 1 cuts in, then relay 2, etc. Cutout takes place in the opposite sequence. (”First in, last out”).

2.Cyclic: An automatic operating time equalisation is arranged here, so that all steps with motor connection will have the same operating time

Unloaders’ cutin and cutout mode	c09	Unloader
The relays for unloaders can be set to switch on when more capacity is required (set-		(switch on = 0)
ting = 0), or they can switch off when more capacity is called for (setting = 1).		(switch off = 1)
Manual control of compressor capacity	c31	CmpManCap%
This sets the capacity that is to be cut in when switching to manual control.
(c01 and c07 will still apply)
Manual control	c32	CmpManCap
Manual control of the compressor capacity is enabled here.
When set to ON, the capacity that is set in “c31” is cut in.

AK-PC 520

	-	- - - Comp. Cap %
		Read cut-in compressor capacity
		Actuel zone state:
		0=off. 1= --zone. 2=-zone. 3=Neutral-
		zone. 4=+zone. 5=++zone
Condenser capacity
Definition of condenser and number of fans	c29	Fan mode
Here you set the number of fan steps with which regulation has to be carried out (but
max. four).
1-4: All fans are cut in and out with relays. The first vacant relay number is assigned to
fan 1, the next to number 2, etc.
5-8: Not used
9: All fans controlled via the analog output and a frequency converter.
10: Not used
11-14: Total number of fan relays (as 1-4), but here the starting sequence is altered
after each time all fans are stopped.
Read temperature at sensor Sc3	u44	Sc3 temp

Read temperature at sensor Sc4 (sensor is only used for monitoring)	u45	Sc4 temp

	-	- - - Fan Cap %
		Read cut-in condenser capacity
Regulation parameters for the condenser regulation
Proportional band xp (P = 100/Xp)	n04	Xp K
If the Xp value is increased, the regulation becomes steadier

I: Integration time Tn	n05	Tn s
If the Tn value is increased, the regulation becomes steadier
Manual control of condenser capacity	n52	FanManCap%
This sets the capacity that is to be cut in when switching to manual control.
Manual control	n53	FanManCap
Manual control of the condenser capacity is enabled here.
When set to ON, the capacity that is specified in “n52” is cut in.
Speed control start value	n54	StartSpeed
Speed control will only be activated when the capacity requirement reaches this
value.
Speed control stop value	n55	MinSpeed
Speed control will be stopped when the capacity requirement falls below this value.
Alarm		Alarm settings
The controller can give alarm in different situations. When there is an alarm the light-
emitting diodes (LED) will flash on the display and the alarm relay will cut in.
P0 min. (Alarm and safety function, see also page 20.)	A11	Min. P0. b
Here you set when the alarm at too low suction pressure is to enter into effect. The
value is set as an absolute value.
Alarm delay P0 alarm	A44	P0AlrmDelay
The time delay is set in minutes. At min. setting the alarm is cancelled.
Pc max. (Alarm and safety function, see also page 20.)	A30	Max. Pc. b
Here you set when the alarm at too high condensing pressure is to enter into effect.
The value is set as an absolute value.

Alarm delay Pc alarm	A45	PcAlrmDelay
The time delay is set in minutes. At min. setting the alarm is cancelled.
Alarm delay DI1 (an interrupted input will give alarm).	A27	DI1AlrmDelay
The time delay is set in minutes. At max. setting the alarm is cancelled.
Alarm delay DI2 (an interrupted input will give alarm).	A28	DI2AlrmDelay
The time delay is set in minutes. At max. setting the alarm is cancelled.
Alarm delay DI3 (an interrupted input will give alarm).	A29	DI3AlrmDelay
The time delay is set in minutes. At max. setting the alarm is cancelled.
Alarm limit for high temperature of the “Saux1” sensor	A32	Saux1 high
With setting = Off the alarm has been opted out.
Alarm delay from "Saux1" (A32)	A03	Alarm delay
If the limit value is exceeded, a timer function will commence. The alarm will not be-
come active until the set time delay has been passed. The time delay is set in minutes.
Give the top button a brief push to zeroset the alarm and to have the message shown		Reset alarm
on the display.		The function zerosets all alarms when
		set in pos. ON.
		With data communication the impor-
		tance of the individual alarms can be
		defined. Setting is carried out in the
		“Alarm destinations” menu.

AK-PC 520

Miscellaneous		Miscellaneous

Choice of application	o61	This setting cannot be made via data
The regulator can be configured in various ways. The use that is required out of the		communication. It must be set directly
two uses available is set here. The functions for the two uses can be viewed on page		on the controller.
14. This menu must be set as the first of all menus, as it enables the associated settings to
be set.
1. Show temperature
2: Show pressure

Sensor type (Sc3, Sc4 and "Saux1") (see also overview page 21)	o06	Sensor type
Normally a Pt1000 sensor with great signal accuracy is used for temperature measure-
ment and AKS 32R for pressure measurement. But a PTC sensor may also be used (r25
= 1000) in special situations.
All temperature sensors must be of the same kind.
In brine cooling the pressure measurements are replaced by temperature measure-
ments.
The following settings are possible:
0=PT1000. 1=PTC1000. 2=PT1000 on sensors and on Po. 3=PTC1000 on sensors and
on Po. 4=PT1000 on sensors and on Pc. 5=PTC1000 on sensors and on Pc. 6=PT1000
on sensors, on Po and on Pc. 7=PTC1000 on sensors, on Po and on Pc.
(If a temperature sensor is mounted on P0 or Pc, the respective settings in o20, 21, 47
and 48 will not be required).
Settings at water cooler application	o81	Ctrl.Sensor
Definition of the signal inlet when compressor regulation is controlled with signal
from a temperature sensor:
0. Temperature signal on terminal 57-58 (P0 inlet)
1. Temperature signal on Saux inlet
2. Temperature signal on Sc4 inlet
(P0 min. function (A11) will not be affected by the definition)
If frost protection is required, you must connect a pressure transmitter on P0 and the
temperature sensor must be connected to the Saux or Sc4 input.
Display connection	o82
This is where you define the type of display that is connected to the controller
Off: EKA 164
On: EKA 165. The extended display with LEDs.
Read temperature at sensor "Saux1"	o49	Saux1 temp
Pressure transmitter’s working range
Depending on the pressure, a pressure transmitter with a given working range is		If the values are to be set from the
used. This working range must be set in the controller (e.g.: -1 to 12 bar		AKM programme, they must be set in
The values must be set in bar if display in °C has been selected. And in psig, if °F has		bar.
been selected.
P0-Min. value	o20	P0MinTrsPres
P0-Max. value	o21	P0MaxTrsPres
Pc-Min. value	o47	PcMinTrsPres
Pc-Max. value	o48	PcMaxTrsPres
Use of DI1 input	o78	Di1 control
The digital input can be connected to a contact function, and the contact can now be
used for one of the following functions:
Setting / function:
0: DI input not used
1: Fan alarm when contact cuts out. Alarm "A34" is given.
2: Alarm function when the contact cuts out. Alarm “A28” is given.
There is time delay for the alarm. Setting in "A27".
Use of DI4 input	o22	Di4 control
The digital input can be connected to a contact function, and the contact can now be
used for one of the following functions:
Setting / function:
0: DI input not used
1: Regulation reference P0 displaced when contact is cut in
2: Alarm function when the contact cuts out. Alarm “A31” is given. There is no time
delay.
Use of DI5 input	o37	Di5 control
The digital input can be connected to a contact function, and the contact can now be
used for one of the following functions:
Setting / function:
0: DI input not used
1: Regulation reference Pc displaced when contact is cut in
2: Alarm function when the contact cuts out. Alarm “A32” is given. There is no time
delay

AK-PC 520

Operating hours		(In the AKM display the hour number
The operating hours for the compressor relays can be read and set in the follow-		has not been multiplied)
ing menus. The read value is multiplied by 1000 to obtain the number of hours (f.ex.
shows 2.1 for 2100 hours). On reaching 99.9 hours the counter stops and must now be
reset to, say, 0. There will be no alarm or error message for counter overflow.
Value for relay number 1 to 4	o23-	DO1 run hour.....
	o26	DO4 run hour
Refrigerant setting	o30	Refrigerant
Before refrigeration is started, the refrigeration must be defined. You may choose
between the following refrigerants:
1=R12. 2=R22. 3=R134a. 4=R502. 5=R717. 6=R13. 7=R13b1. 8=R23. 9=R500.
10=R503. 11=R114. 12=R142b. 13=User defined. 14=R32. 15=R227. 16=R401A.
17=R507. 18=R402A. 19=R404A. 20=R407C. 21=R407A. 22=R407B. 23=R410A.
24=R170. 25=R290. 26=R600. 27=R600a. 28=R744. 29=R1270. 30=R417A.
31=R422A.
Warning: Wrong selection of refrigerant may cause damage to the compressor.
Other refrigerants: Select setting 13 here, and subsequently three factors have to be
set – fac1, fac2 and fac3 – via AKM.
Manual control (stopped regulation only)	o18	- - -
From this menu the relays can be cut in and out manually. 0 gives no override, but a
number between 1 and 10 will cut in a belonging relay. 1 will cut in relay number 1, 2
relay 2, etc.
11-18 will produce voltage on the analog output. Setting 11 will give a voltage of
1.25 V, setting 12 will give 2.5 V, etc.

Frequency	o12	50 / 60 Hz
Set the net frequency.		(50=0, 60=1)
Address
If the controller is built into a network with data communication, it must have an		Following installation of a data com-
address, and the master gateway of the data communication must then know this		munication module, the controller can
address.		be operated on a par with the other
These settings can only be made when a data communication module has been		controllers in ADAP-KOOL® refrigera-
mounted in the controller and the installation of the data communication cable has		tion controls.
been completed.
This installation is mentioned in a separate document “RC8AC”.
The address is set between 1 and 240 (gateway determined)	o03
The address is sent to the gateway when the menu is set in pos. ON	o04
Access code	o05
If the settings in the controller are to be protected by a numerical code, you can set a
numerical value between 0 and 100. If not, you can cancel the function with setting
OFF.
Special settings
Outputs DO9 and DO10 are normally used for the ”AKD start/stop” function and for the alarm
function, but they may be redefined in special cases.
DO9 function:	o75	DO9 function
0: AKD Start/stop
1: Inject-on function (see drawing below)
2: Boost ready function (see drawing below)
3: Not used
DO10 function:	o76	DO10 function
0: Alarm relay
1: Not used
Status on the digital inputs
The signal on the DI inputs can be read in the following menus:
Status on DI 1	u10	DI 1 Status
Status on DI 2	u37	DI 2 Status
Status on DI 3	u87	DI 3 Status
Status on DI 4	u88	DI 4 Status
Status on DI 5	u89	DI 5 Status

AK-PC 520

+ 16 hidden pages