Danfoss EKC 316A User guide
Controller for operation of
evaporator on water chiller
EKC 316A
Manual
2 Manual RS8CX802 © Danfoss 04-2009 EKC 316A
Contents
Introduction ....................................................................................................... 2
Operation ............................................................................................................ 3
Survey of functions .......................................................................................... 4
Operation ............................................................................................................ 8
Introduction
Application
The controller and valve can be used where there are requirements to accurate control of superheat and temperature in connection with refrigeration.
E.g.:
• Processing plant (water chillers)
• Cold store (air coolers)
• 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 injection ensures optimum utilisation of the evaporator and hence a
high suction pressure.
• The superheating is regulated to the lowest possible value at
the same time as the media temperature is controlled by the
thermostat function.
Menu survey ....................................................................................................... 8
Data .....................................................................................................................10
Connections .....................................................................................................10
Ordering ............................................................................................................10
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
System
The superheat in the evaporator is controlled by one pressure
transmitter P and one temperature sensor S2.
The expansion valve is with step motor of the type ETS.
If temperature control is required, this can be accomplished via
a signal from temperature sensor S3 placed in the air flow before
the evaporator. The temperature control is an ON/OFF thermostat
that opens for the liquid ow when refrigeration is required – the
ETS valve opens and the thermostat relay cuts in.
For safety reasons the liquid ow to the evaporator must be cut
off if there is power failure for the controller. As the ETS valve is
provided with step motor, it will remain open in such a situation.
There are two ways of coping with this situation:
- Mounting of a solenoid valve in the liquid line
- Mounting of battery backup for the valve
Superheat regulation
Shown on page 12 are the different forms of regulation
algorithms which the controller can be set for.
EKC 316A Manual RS8CX802 © Danfoss 04-2009 3
Operation
Superheat function
You may choose between two kinds of superheat, either:
• Adaptive superheat or
• Load-dened superheat
MOP
The MOP function limits the valve’s opening degree as long as the
evaporating pressure is higher than the set MOP value.
Override function
Via the analog input a displacement can be made of the temperature reference or of the superheat reference. The signal can either
be a 0-20 mA signal or a 4-20 mA signal. The reference can be
dsplaced in positive or negative direction.
The signal can be used to override the valve's opening degree.
External start/stop of regulation
The controller can be started and stopped externally via a contact
function connected to input terminals 1 and 2. Regulation is
stopped when the connection is interrupted. The function must
be used when the compressor is stopped. The controller then
closes the solenoid valve so that the evaporator is not charged
with refrigerant.
Relays
The relay for the solenoid valve will operate when refrigeration is
required. The relay for the alarm function works in such a way that
the contact is cut in in alarm situations and when the controller is
de-energised.
PC operation
The controller can be provided with data communication so that it
can be connected to other products in the range of ADAP-KOOL®
refrigeration controls. In this way operation, monitoring and data
collection can be performed from one PC – either on the spot or in
a service company.
See also page 14.
4 Manual RS8CX802 © Danfoss 04-2009 EKC 316A
Survey of functions
Function Para-
meter
Normal display
Normally the superheat is shown (but the valve’s opening degree or air temperature
may also be selected. See o17).
Reference Thermostat control
Set point (set only if r14=1)
Regulation is performed based on the set value provided that there is no external
contribution (o10).
(Push both buttons simultaneously to set the setpoint).
Differential
When the temperature is higher than the reference plus the set dierential, the solenoid valve’s relay will be activated. It will become deactivated when the temperature
drops below the set reference.
Ref. Diff.
Unit
Here you select whether the controller is to indicate the temperature values in °C or
in °F.
And pressure values in bar or psig.
If indication in °F is selected, other temperature settings will also change over to
Fahrenheit, either as absolute values or as delta values
The combination of temperature unit and pressure unit is depicted to the right.
External contribution to the reference
This setting determines how large a contribution is to be added to the set setpoint
when the input signal is max. (20 mA). See o10.
Correction of signal from S2
(Compensation possibility through long sensor cable).
Correction of signal from S3
(Compensation possibility through long sensor cable).
Start/stop of refrigeration
With this setting refrigeration can be started and stopped. Start/stop of refrigeration
can also be accomplished with the external switch function. See also appendix 1.
Parameter by operation via
data communication
SH / OD% / S3 temp
- * TempSetpoint.
r01 * Differential
r05 Units (Menu = Misc.)
0: °C + bar
1: °F + psig
(in AKM only °C + bar – is displayed
– whatever the setting).
r06 ExtRefOset
r09 Adjust S2 (Menu = Misc.)
r10 Adjust S3 (Menu = Misc.)
r12 Main Switch
Define thermostat function
0: No thermostat function. Only the superheat is regulated
1: Thermostat function as well as regulation of superheat.
Alarm Alarm setting
The controller can give alarm in different situations. When there is an alarm all the
light-emitting diodes (LED) will ash on the controller front panel, and the alarm relay
will cut in.
Alarm for upper deviation
The alarm for too high S3 temperature is set here. The value is set in Kelvin. The alarm
becomes active when the S3 temperature exceeds the actual reference plus A01. (The
actual reference can be seen in u28).
Alarm for lower deviation
The alarm for too low S3 temperature is set here. The value is set in Kelvin. The alarm
becomes active when the S3 temperature drops below the actual reference minus
A02.
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 minutes.
Battery alarm
Here it is dened whether the controller is to monitor the voltage from the battery
backup. If there is low voltage or no voltage alarm will be given.
*) Only used if thermostat function (r14 = 1) is also to be selected.
r14 Therm. Mode
A01 * Upp.TempAlrm
A02 * Low.TempAlrm
A03 * TempAlrmDel
A34 Batt. alarm
EKC 316A Manual RS8CX802 © Danfoss 04-2009 5
With data communication the importance of the individual alarms can be
dened. Setting is carried out in the
“Alarm destinations” menu. See also
page 14
Control parameters Injection control
P: Amplification factor Kp
If the Kp value is reduced the regulation becomes slower.
I: Integration time Tn
If the Tn value is increased the regulation becomes slower.
D: Differentiation time Td
The D-setting can be cancelled by setting the value to min. (0).
Max. value for the superheat reference n09 Max SH
Min. value for the superheat reference
Warning! Due to the risk of liquid ow the setting should not be lower than approx.
2-4 K.
MOP
If no MOP function is required, select pos. O.
Start-up time for safety signal
If the controller does not obtain a reliable signal within this period of time the controller will in other ways try to establish a stable signal. (A too high value may result in
a ooded evaporator).
The value should only be changed by specially trained sta.
Signal safety during start-up
The control function uses the value as start value for the valve’s opening degree at
each thermostat cutin. By adaptive control the controller continuously calculates a
new value.
The value should only be changed by specially trained sta.
Stability factor for regulation of superheat
With a higher value the control function will allow a greater fluctuation of the super-
heat before the reference is changed. The value should only be changed by specially
trained staff.
Damping of amplification near reference value
This setting damps the normal amplication Kp, but only just around the reference
value. A setting of 0.5 will reduce the KP value by half.
The value should only be changed by specially trained sta.
Amplification factor for the superheat
This setting determines the valve’s opening degree as a function of the change in
evaporating pressure. An increase of the evaporating pressure will result in a reduced
opening degree. When there is a drop-out on the low-pressure thermostat during
start-up the value must be raised a bit. If there is pendling during start-up the value
must be reduced a little.
The value should only be changed by specially trained sta.
Definition of superheat regulation (Ref. appendix 3)
1: Lowest permissible superheat (MSS). Adaptive regulation.
2: Load-dened superheat. The reference is established based on the line formed by
the three points: n09, n10 and n22.
Value of min. superheat reference for loads under 10%
(The value must be smaller than ”n10”).
Max. opening degree (AKV only)
The valve’s opening degree can be limited. The value is set in %
The parameters ”n37” to ”n42” are settings for step motor ETS 50. The settings in
n37 must be changed when another valve is used. The other settings should not
be changed.
Number of steps from 0% to 100% open n37 Max. steps (0 - 5000 step)
Spindle stroke speed (number of steps per second) n38 Steps / sec (10 - 300 step/sec)
Compensation value for spindle play at valve’s closing point (number of steps) n39 Start bcklsh (Menu=Danfoss only)
Compensation value for spindle play during operation (number of steps) n40 Backlash (Menu=Danfoss only)
Valve denition
1=Valve must open when more capacity is required (NC function)
2=Valve must close when more capacity is required (NO function)
Compensation direction
1=Compensation takes place when the valve opens (normal setting)
2=Compensation takes place when the valve closes
Attenuation factor for the inner loop gain
Used only when o56 = 2 or 3.
The value should only be changed by specially trained sta.
n04 Kp factor
n05 Tn sec.
n06 Td sec.
n10 Min SH
n11 MOP (bar)
(A value on max (60) corresponds to
O)
n15 StartUp time
n17 Start OD%
n18 Stability
n19 Kp Min
n20 Kp T0
n21 SH mode
n22 SH Close
n32 ETS OD% Max (Menu=Danfoss only)
n41 Valve type (Menu=Danfoss only)
n42 Comp.dir. (Menu=Danfoss only)
n43 Atten. factor