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-dened 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 dierential, 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 ExtRefOset

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 dened 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

dened. 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 amplication 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-dened 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 denition

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