Danfoss EKC 331 User guide
REFRIGERATION AND
AIR CONDITIONING
Capacity controller
EKC 331
Manual
Introduction
Application
The controller is used for capacity regulation of compressors or
condensers in small refrigerating systems.
Advantages
• Patented neutral zone regulation
• Sequential or cyclic operation
Functions
• Regulation
Regulation with up to four relay outputs can be carried out.
Regulation takes place with a set reference which is compared
to a signal from a pressure transmitter.
• Relay module
It is possible to use the controller as relay module, so that the
relays are cut in or out by means of an external voltage signal.
• Alarmfunction
A relay becomes activated when the set alarm limits are exceeded.
• Digital input
The digital input can be used for:
- night operation where the suction pressure is raised
- heat recovery where the condensing pressure is raised
- external start/stop of the regulation.
Function
Capacity regulation
The cut-in capacity is controlled by signals from the connected
pressure transmitter 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.
The size of the +zone and -zone is identical and defi ned to be
constantly 0.7 times the set value of the neutral zone.
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. The set time delays will
here be reduced by factor 0.3.
Cutin of steps can be defi ned for either sequential or cyclic operation.
Relay module
The controller can also be used as a relay module where the relays
in the module will then be controlled by the received voltage
signal.
Depending on the defi nition of the signal and the number of
relays used, the relays will be “distributed” over the signal.
A hysteresis around the individual cutin and cutout points will
ensure that the relay will not cut in or out when it is not called for.
2 Manual RS.8A.G2.02 © Danfoss 10-2000 EKC 331
Survey of functions
Function Para-
Normal display
Normally the signal from the pressure transmitter is shown. If the controller is used as
relay module, U
Pressure regulation Reference
Regulation reference
Regulation is based on the set value.
(Push both buttons simultaneously to set the menu.)
Neutral zone
There is a neutral zone around the reference. See also page 2.
Displacement of reference
The set reference may be displaced with a fi xed value when a signal is received at the
DI input. Regulation will then be based on the set reference plus the value set here.
The total reference can be seen when you push the lower of the two buttons. (Cf. also
Defi nition of DI input).
Reference limitation
The controller’s setting range for the reference can be narrowed down, so that you
cannot accidentally set a too high or too low value - that may result in damage to the
system. With these settings the reference can only be set between the two values.
Max. permissible reference value. r02 Max. set point
Min. permissible reference value. r03 Min. set point
Pressure unit
Here you can select whether the controller is to indicate the pressure in bar or psig.
(When psig is selected, the settings must also be in psig).
Alarm Alarm settings
The controller can give alarm in diff erent situations. When there is an alarm all the
light-emitting diodes (LED) will fl ash on the controller front panel, and the alarm relay
will cut in.
Upper deviation
Here you set when the alarm at high pressure is to enter into eff ect. The value is set as
an absolute value.
See also emergency procedure page 5.
Lower deviation
Here you set when the alarm at low pressure is to enter into eff ect. The value is set as
an absolute value.
See also emergency procedure page 5.
Alarm delay
If one of the two limit values is exceeded, a timer function will commence. The alarm
will not become active until the set time delay has been passed. The time delay is set
in seconds.
Give the top button a brief push to zeroset the alarm and to have the message shown
on the display.
will appear on the display.
in
meter
Parameter by operation via data
communication
Pressure
- Press. set point
r01 Neutral zone
r13 Pressure off set
r05 Unit
bar=0
psig=1
(In AKM only bar is used, whatever the
setting).
A10 Max. pressure
A11 Min. pressure
A03 Alarm delay
Reset alarm
The function zerosets all alarms when
set in pos. ON.
Alarm relay
Here you can read the status of the
alarm relay.
(ON indicates operation with alarm).
With data communication the importance of the individual alarms can be
defi ned. Setting is carried out in the
“Alarm destinations” menu. See also
page 8.
EKC 331 Manual RS.8A.G2.02 © Danfoss 10-2000 3
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