2 Manual RS8CS302 © Danfoss 07-2005 EKC 315A
Introduction
Application
The controller and valve can be used where there are require
-
ments to accurate control of superheat and temperature in con-
nection with refrigeration.
E.g.:
• Cold store (air coolers)
• Processing plant (water chillers)
• A/C plant
Advantages
• The evaporator is charged optimally – even when there are great
variations of load and suction pressure
• Energy savings – the adaptive regulation of the refrigerant injec
-
tion ensures optimum utilisation of the evaporator and hence a
high suction pressure
• Exact temperature control – the combination of adaptive
evaporator and temperature control ensures great temperature
accuracy for the media
• The superheating is regulated to the lowest possible value at
the same time as the media temperature is controlled by the
thermostat function
Functions
• Regulation of superheat
• Temperature control
• MOP function
• ON/OFF input for start/stop of regulation
• Input signal that can displace the superheat reference or the
temperature reference
• Alarm if the set alarm limits are exceeded
• Relay output for solenoid valve
• PID regulation
• Output signal following the temperature showing in the display
System
The superheat in the evaporator is controlled by one pressure
transmitter P and one temperature sensor S2.
The valve can be one of the following types:
• TQ (PHTQ, TEAQ)
• AKV (AKVA)
TQ is a modulating valve, and when this is used a solenoid valve
must also be used in the liquid line.
AKV is a pulsating valve.
Where the AKV valve is used it also functions as solenoid valve.
Temperature control is performed based on a signal from tem
-
perature sensor S3 which is placed in the air current before the
evaporator. Temperature control is in the shape of an ON/OFF
thermostat that shuts off the liquid flow in the liquid line, either
via the solenoid valve in TQ applications or directly when AKV is
used.
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