Danfoss Superheat Controller, type EKD 316,084B8040 introduction
EKD 316 is a superheat controller for the stepper motor valve that can be used where there are requirements for accurate control of superheat in connection with refrigeration.The controller and valve can be used where
there are requirements for accurate control of superheat in connection with refrigeration.
Applications:
Processing plant (water chillers)
Cold store (air coolers)
A/C plant
Heat pumps
Air conditioning
Danfoss Superheat Controller, type EKD 316,084B8040 Advantages
The superheat is regulated to the lowest possible value.
The evaporator is charged optimally – even when there are great variations of load and suction pressure.
Energy savings – the adaptive regulation of the refrigerant injection ensures optimum utilisation of the evaporator and thus a high suction pressure.
Danfoss Superheat Controller, type EKD 316,084B8040 Main features
Regulation of superheat
MOP function
ON/OFF input for start/stop of regulation
Relay output to alarm
MOD bus communication
Safety features and
Alarm indications
Danfoss Superheat Controller, type EKD 316,084B8040 Function overview
Minimum Stable Superheat (MSS)
The controller will search for the minimum stable superheat
between an upper and lower boundry. If the superheat has been
stable for a period, the superheat reference is decreased. If the
superheat becomes unstable, the reference is raised again. This
process continues as long as the superheat is within the bounds
set by the user. The purpose of this is to search for the lowest
possible superheat that can be obtained while still maintaining a
stable system. The superheat reference can also be fixed, in which
case this function is disabled.
Maximum Operating Pressure (MOP)
In order to reduce the strain of the compressor, a maximum
operating pressure can be set. If the pressure comes above this
limit, the controller will control the valve to provide a lower
pressure instead of a low superheat. The limit for this function
is usually a fixed pressure, but it is possible to offset the limit
temporarily.
Stand-alone function
EKD 316 is designed to operate in conjunction with a system
master controller, which will control the EKD 316 via MODBUS or
analog signal. It is however possible to use it in a standalone mode
using one temperature and one pressure transducer.
Manual Control as a valve driver
The valve can be controlled manually by setting the desired
operating degree using MODBUS. Alternatively, the controller may
also be started and stopped externally using the analog signal 4 to
20 mA/0 to 10 V d.c., /1 to 5 V d.c.
Forced opening during startup
In some applications it is necessary to open the valve quickly when
the compressor turns on to prevent suction pressure becoming
too low. This is ensured by setting a fixed opening degree and
a startup time for the controller. Note that this will give a fixed
opening degree for the duration of the start time, regardless of the
superheat value.
Relay
The relay for the alarm function is an alternating relay. In the event
of an alarm, the relay will close, which may, for instance, be used
for an alarm buzzer.
