Product Overview

© Danfoss | DCS | 2019.04
Data sheet | Superheat controller type EKE 1A, EKE 1B, EKE 1C
DKRCC.PD.RS0.A4.02 | 8
The superheat control algorithm will attempt to regulate the superheat down to the lowest stable
value between the minimum superheat setting, “Min SH” and the maximum superheat setting,
“Max. SH” .
LoadAP is an abbreviation of “load dened reference. LoadAP will adjust reference to be higher if
load is higher. Load is indicated by the OD of valve. LoadAP is a kind of preprogrammed MSS curve.
This method will give a robust SH reference and can in many case be the best t for systems.
This feature is used in a system where a stable xed superheat is required.
With delta temp., SH reference is calculated as a ratio between the media temperature and
evaporator temperature. This reference mode is only possible if media temperature (S3) sensor is
available and if the system uses n and tube evaporator.
EKE has a feature to regulate the temperature control. This can be done with either thermostat cut
in -cut out function or using Modulating Thermostat (MTR) i.e Area control of Evaporator.This
feature is typically used in Food retail application. MTR is generally used with variable speed
compressors. This feature will control the evaporating temperature in a smooth way to ensure a
stable food temperature.
In order to reduce the strain on the compressor, a maximum operating pressure is set. If the pressure
comes above this limit the controller will control the valve to provide a lower pressure instead of a
low superheat.
This feature which is also known as Cold start feature that allows applications such as heat pumps
to operate at lower ambient conditions in order to prevent compressor from stopping due to low
suction pressure in the start up phase.
When the superheat is below a set minimum value, the valve will close faster in order to protect the
compressor from the risk of getting liquid in the suction line and bring the superheat back to
superheat reference.
High condensing temperature protection will make sure that the load on the condenser is reduced
in case a too high condensing temperature is reached. This is done by limiting the valve opening
degree.
In some applications, it is necessary to quickly open an EEV valve when compressor turns ON to
prevent too low suction pressure as well as for faster stabilization of superheat or temperature set
point. This can be ensured by setting either P-control , Start opening degree with protection or
Fixed opening degree without protection. This start up condition is kept until the start time expire
or superheat reaches at setpoint.
In some applications valve must remain open when the controller is OFF. This can be done by
setting a xed opening degree. When normal control is switched OFF using a main switch, the
valve will keep the dened opening degree.
The controller does not itself handle defrost of the evaporator. It is however possible to enter a
special defrost sequence which will overrule the normal control of the valve.
During operation, if sensors error occurs, the valve position can be set to full close, xed
opening degree or average calculated OD as required.
A function is provided to indicate lack of valve capacity or loss of refrigerant charge. This is only
indicated by setting an alarm. No special action is performed by the controller.
The wizard tool will guide the user to set up the controller in a fast and easy way. The controller
will then be loaded with the suitable PI values as per dened application and operating conditions.
3.2 Software
Minimum Stable
Superheat (MSS)
LoadAp Superheat
Fixed Superheat
Delta temp. superheat
Temperature Control
Maximum Operating
Pressure (MOP)
Low Operating
Pressure (LOP)
Superheat close
High Condensing
temperature
protection (HCTP)
Fast Start up
Forced opening during
OFF / (Bleed function)
Defrost sequence
Failsafe operation
Lack of Valve Capacity
Wizard tool