Carel EVD mini User manual

Brand: Carel

Model: EVD mini

Category: Measuring, testing & control

Type: User manual

High Efficiency Solutions

EVD mini

NO POWER

& SIGNAL

CABLES

TOGETHER

READ CAREFULLY IN THE TEXT!

User manual

Superheat control for unipolar electronic

expansion valve

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

WARNINGS

CAREL bases the development of its products on decades of experience

in HVAC, on the continuous investments in technological innovations

to products, procedures and strict quality processes with in-circuit and

functional testing on 100% of its products, and on the most innovative

production technology available on the market. CAREL and its subsidiaries

nonetheless cannot guarantee that all the aspects of the product and the

software included with the product respond to the requirements of the ﬁnal

application, despite the product being developed according to start-of-the-

art techniques. The customer (manufacturer, developer or installer of the ﬁnal

equipment) accepts all liability and risk relating to the conﬁguration of the

product in order to reach the expected results in relation to the speciﬁc ﬁnal

installation and/or equipment. CAREL may, based on speciﬁc agreements, acts

as a consultant for the positive commissioning of the ﬁnal unit/application,

however in no case does it accept liability for the correct operation of the ﬁnal

equipment/system.

The CAREL product is a state-of-the-art product, whose operation is speciﬁed

in the technical documentation supplied with the product or can be

downloaded, even prior to purchase, from the website www.carel.com.

Each CAREL product, in relation to its advanced level of technology, requires

setup/conﬁguration/programming/commissioning to be able to operate in

the best possible way for the speciﬁc application. The failure to complete such

operations, which are required/indicated in the user manual, may cause the

ﬁnal product to malfunction; CAREL accepts no liability in such cases.

Only qualiﬁed personnel may install or carry out technical service on the

product.

The customer must only use the product in the manner described in the

documentation relating to the product.

In addition to observing any further warnings described in this manual, the

following warnings must be heeded for all CAREL products:

• prevent the electronic circuits from getting wet. Rain, humidity and all

types of liquids or condensate contain corrosive minerals that may damage

the electronic circuits. In any case, the product should be used or stored

in environments that comply with the temperature and humidity limits

speciﬁed in the manual;

• do not install the device in particularly hot environments. Too high

temperatures may reduce the life of electronic devices, damage them and

deform or melt the plastic parts. In any case, the product should be used

or stored in environments that comply with the temperature and humidity

limits speciﬁed in the manual;

• do not attempt to open the device in any way other than described in the

manual;

• do not drop, hit or shake the device, as the internal circuits and mechanisms

may be irreparably damaged;

• do not use corrosive chemicals, solvents or aggressive detergents to clean

the device;

• do not use the product for applications other than those speciﬁed in the

technical manual.

All of the above suggestions likewise apply to the controllers, serial boards,

programming keys or any other accessory in the CAREL product portfolio.

CAREL adopts a policy of continual development. Consequently, CAREL

reserves the right to make changes and improvements to any product

described in this document without prior warning.

The technical speciﬁcations shown in the manual may be changed without

prior warning.

The liability of CAREL in relation to its products is speciﬁed in the CAREL general

contract conditions, available on the website www.carel.com and/or by

speciﬁc agreements with customers; speciﬁcally, to the extent where allowed

by applicable legislation, in no case will CAREL, its employees or subsidiaries

be liable for any lost earnings or sales, losses of data and information, costs of

replacement goods or services, damage to things or people, downtime or any

direct, indirect, incidental, actual, punitive, exemplary, special or consequential

damage of any kind whatsoever, whether contractual, extra-contractual or

due to negligence, or any other liabilities deriving from the installation, use or

impossibility to use the product, even if CAREL or its subsidiaries are warned

of the possibility of such damage.

DISPOSAL

INFORMATION FOR USERS ON THE CORRECT

HANDLING OF WASTE ELECTRICAL AND ELEC-

TRONIC EQUIPMENT (WEEE)

In reference to European Union directive 2002/96/EC issued on 27 January

2003 and the related national legislation, please note that:

1. WEEE cannot be disposed of as municipal waste and such waste must be

collected and disposed of separately;

2. the public or private waste collection systems deﬁned by local legislation must

be used. In addition, the equipment can be returned to the distributor at

the end of its working life when buying new equipment;

3. the equipment may contain hazardous substances: the improper use or

incorrect disposal of such may have negative eﬀects on human health

and on the environment;

4. the symbol (crossed-out wheeled bin) shown on the product or on the

packaging and on the instruction sheet indicates that the equipment has

been introduced onto the market after 13 August 2005 and that it must

be disposed of separately;

5. in the event of illegal disposal of electrical and electronic waste, the penalties

are speciﬁed by local waste disposal legislation.

Warranty on the materials: 2 years (from the date of production, excluding

consumables).

Approval: the quality and safety of CAREL INDUSTRIES products are

guaranteed by the ISO 9001 certiﬁed design and production system, as well

as by the marks (*).

CAUTION: separate as much as possible the probe and digital input signal

cables from the cables carrying inductive loads and power cables to avoid

possible electromagnetic disturbance.

Never run power cables (including the electrical panel wiring) and signal

cables in the same conduits.

NO POWER

& SIGNAL

CABLES

TOGETHER

READ CAREFULLY IN THE TEXT!

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

Content

1. INTRODUCTION 7

1.1 Models ............................................................................................................... 7

1.2 Functions and main characteristics ............................................................. 7

1.3 Accessories ....................................................................................................... 7

2. INSTALLATION 8

2.1 Dimensions and mounting-mm (in) .......................................................... 8

2.2 Description of the terminals ......................................................................... 9

2.3 Wiring diagram for superheat control ...................................................... 10

2.4 Installation ...................................................................................................... 10

2.5 Copy parameters with programming key ................................................ 11

3. USER INTERFACE 12

3.1 Keypad............................................................................................................. 12

3.2 Display ............................................................................................................. 12

3.3 Programming mode ..................................................................................... 12

3.4 Restore factory parameters (default) ........................................................ 12

4. COMMISSIONING 13

5. FUNCTIONS 15

5.1 Control ............................................................................................................. 15

5.2 Analogue positioner (0-10 Vdc) ................................................................. 16

5.3 Superheat control with 2 temp. probes ................................................... 16

5.4 Special functions ............................................................................................17

5.5 Regolazione speciale: smooth lines ...........................................................17

5.6 Control parameters for protection functions .......................................... 18

5.7 Service parameters ....................................................................................... 18

6. PROTECTORS 19

6.1 Protectors ........................................................................................................ 19

7. PARAMETERS TABLE 21

8. NETWORK CONNECTION 23

8.1 RS485 serial conﬁguration ..........................................................................23

8.2 Network connection for commissioning via PC .....................................23

8.3 Visual parameter manager ..........................................................................23

8.4 Restore default parameters .........................................................................24

8.5 Setup by direct copy .....................................................................................24

8.6 Setup using conﬁguration ﬁle ....................................................................25

8.7 Read the conﬁguration ﬁle on the controller ..........................................25

8.8 Variables accessible via serial connection ...............................................26

8.9 Control states .................................................................................................27

8.10 Special control states ....................................................................................28

9. ALARMS 30

9.1 Types of alarms ..............................................................................................30

9.2 Probe alarms ..................................................................................................30

9.3 Control alarms ...............................................................................................30

9.4 Valve emergency closing procedure .........................................................30

9.5 Network alarm ............................................................................................... 31

9.6 Alarm table ..................................................................................................... 31

10. TROUBLESHOOTING 32

11. TECHNICAL SPECIFICATIONS 34

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

1. INTRODUCTION

EVD mini is a range of drivers designed for the control of CAREL single-

pole electronic expansion valves used in refrigerant circuits. EVD

mini controls refrigerant superheat and optimises refrigerant circuit

performance; it guarantees signiﬁcant system ﬂexibility being compatible

with various types of refrigerants, in applications with refrigerators and

chiller/air-conditioners. It features low superheat protection (LowSH), high

evaporation pressure (MOP) and low evaporation pressure (LOP) functions.

As regards network connectivity, the driver can be connected via serial

RS485/ Modbus® to:

• a pCO programmable controller

• a CAREL supervisor.

Another possibility involves operation as a simple positioner with 0 to 10

Vdc analogue input signal, or as a manual positioner via RS485. EVD mini

can be supplied with LED display for information on the instant superheat

value and any active alarms, or for performing the commissioning

operations. The latter involves setting just three parameters: refrigerant,

operating mode (showcase, air conditioner, etc.) and superheat set point.

The driver can also be setup using a computer via the serial port. In this

case, the VPM program (Visual Parameter Manager) needs to be installed,

downloadable from http://ksa.carel.com, and the USB-RS485 converter

connected.

1.1 Models

P/N Description

EVDM001N00 EVD mini 24 V with display

EVDM000N00 EVD mini 24 V without display

EVDM010N00 EVD mini 115/230 V without display

EVDM011N00 EVD mini 115/230 V with display

Tab. 1.a

1.2 Functions and main characteristics

In summary:

• superheat control with LowSH, MOP, LOP functions;

• compatibility with various types of refrigerants;

• guided setup procedures ﬁrst, entering just three parameters on the

user interface: refrigerant (Gas), type of control (Mode) and superheat

set point (Superheat);

• activation/deactivation of control via digital input or remote control

via serial connection;

• controller and valve power supply incorporated (230 V/115 V);

• RS485 serial communication incorporated (Modbus protocol);

• IP65;

• operating conditions: -25T60C° (-13T140°F);

• compatible with Carel E2V and E3V single-pole valves.

From software revision 1.6 and higher, new functions have been

introduced:

• hot gas bypass by pressure;

• hot gas bypass by temperature.

The smooth lines function has been introduced starting from software

revision 1.8.

1.3 Accessories

Pressure probe cable (see technical leaﬂet +050000484), pressure

probe (-1…9.3 barg, P/N SPKT0013P0) and temperature probe (P/N

NTC006HP0R).

Fig. 1.a

The ratiometric pressure probe speciﬁed as default for assembly is P/N

SPKT0013P0, with an operating range from -1 to 9.3 barg. Alternatively,

other probes can be installed, setting the corresponding parameter

accordingly. See the “Functions” chapter..

P/N Type P/N Type

SPKT0053P0 -1…4.2 barg SPKT00B6P0 0…45 barg

SPKT0013P0 -1…9.3 barg SPKT00E3P0 -1…12.8 barg

SPKT0043P0 0…17.3 barg SPKT00F3P0 0…20.7 barg

SPKT0033P0 0…34.5 barg

Tab. 1.b

Single-pole valve (P/N E2V**F**C1/ E3V**B**C1)

Fig. 1.b

Ultracap module (P/N EVDMU**N**)

The module guarantees temporary power to the driver in the event of

power failures, for enough time to immediately close the connected

electronic valve. It avoids the need to install a solenoid valve. The module

is made using Ultracap storage capacitors, which ensure reliability in terms

of much longer component life than a module made with lead batteries.

Fig. 1.c

Ferrite (P/N 0907879AXX)

Clamp-on ferrite for use in certain applications. See the technical

speciﬁcations table.

Fig. 1.d

Programming key with power supply (P/N IROPZKEYA0)

The key can be used to quickly program the controllers, reducing the risk

of errors. This accessory also allows fast and eﬀective technical service,

and can be used for programming the controllers in just a few seconds,

also during the testing phase.

Fig. 1.e

USB/RS485 converter (P/N CVSTDUMOR0)

The converter ensures connection between the computer used for

conﬁguration and the EVD mini driver.

Fig. 1.f

GAS Type

Mode

Super Heat

(2.8)

88 (3.5)

(3.9)

(3.7)

60 (2.4)

33 (1.3)

BASSO/ BOTTOM

74,1 (2.9)

(3.4)

BASSO/ BOTTOM

42,7 (1.68)

70,7 (2.78)

GAS Type

Mode

Super Heat

113,7 (4.48)

117 (4.60)

GAS

ype

Mode

Super He

GAS

Type

Mode

Super He

74,10 (2.9)

72 (2.8)

Ø 4 (0.2)

GAS Type

Mode

Super Hea

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

2. INSTALLATION

2.1 Dimensions and mounting-mm (in)

Mounting

on DIN rail: with screws

EVD mini (24 V) YES YES

EVD mini (230 V) YES NO

EVD mini (24 V)

Fig. 2.a

EVD mini (230 V)

Fig. 2.b

On DIN rail mounting:

1. Fasten the DIN rail and ﬁt the controller from point

;

2. 24V model: use a screwdriver to remove the two side slots before

installing any other controllers alongside.

EVD mini (24 V)

Fig. 2.c

EVD mini (230 V)

Fig. 2.d

Screw mounting

On the wall, mark the positions of the holes as per the ﬁgure and drill the

holes (Ø < 4mm). Then tighten the fastening screws.

Fig. 2.e

GAS Type

Mode

Super Heat

GND

Tx/Rx+

Tx/Rx-

GND

5Vref

Signal

GND

Signal

+13V (in)

+13V (out)

GND

RS485

Modbus®

CVSTDUM0R0

pCO

ratiometric pressue

transducer

NTC

shield

Ferrite/ Ferrite bead

cod. 0907879AXX

VPM

ULTRACAP

Module

NTC

A B C D

0,3 Nm

CAREL E2 V/ E3V

unipolar valve

digital input to start

the regulation

24 Vdc

20 VA

230 Vac

24 Vac

GAS Type

Mode

Super Heat

S2 S1

GND

Tx/Rx+

Tx/Rx-

RS485

Modbus®

CVSTDUM0R0

pCO

shield

VPM

D I

digital input to start

the regulation

230 Vac

GND

5Vref

Signal

GND

Signal

+13V (in)

+13V (out)

GND

NTC

Ferrite/ Ferrite bead

cod. 0907879AXX

ULTRACAP

Module

C D

ratiometric pressue

transducer

NTC

0,3 Nm

CAREL E2 V/ E3V

unipolar valve

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

2.2 Description of the terminals

EVD mini 24 V EVD mini (230 V)

Fig. 2.f Fig. 2.a

Key:

Ref. Terminal Description Ref. Terminal Description

ExV Single-pole valve connection

(24 Vdc

power

supply)

G Power supply, 24 Vdc

+13 V (in)

Ultracap module connection (accessory)

G0 Power supply, 0 Vdc

+13 V (out) DI Digital input to enable control

GND

(230 V

power

supply)

L 230 V power supply, line

Signal S2 probe (temperature) N 230 V power supply, neutral

Ground Earth for S2 probe DI 230 V digital input to enable control

GND Earth for S1 probe

GND

Terminal for RS485 connection5Vref Power S1 active probe Tx/ Rx +

Signal S1 probe: pressure or temperature Tx/ Rx -

- Connection as positioner (0 to 10 V input)

PC for conﬁguration

Connection for superheat control with 2 temperatu-

re probes

USB – RS485 Converter

(24 Vac

power

supply)

G Power supply, 24 V ac

G0 Power supply, 0 V ac

DI Digital input to enable control

Tab. 2.a

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

2.3 Wiring diagram for superheat control

• EVD mini requires the use of an evaporation pressure probe S1 and

suction temperature probe S2, which will be ﬁtted downstream of

the evaporator, and a digital input to enable control. Alternatively, the

signal to enable control can be sent via a remote RS485 connection;

• input S1 is programmable and connection to the terminals depends

on the parameter settings. See the chapters “Commissioning” and

“Functions”.

Note: for details on installing probes, see the “EEV system guide”

(+030220810).

GAS Type

Mode

Super Heat

GND

Tx/Rx+

Tx/Rx-

CVSTDUM0R0

VPM

2 1

0,3 Nm

CAREL E2 V/ E3V

unipolar valve

digital input to start

the regulation

24 Vdc

20 VA

230 Vac

24 Vac

Fig. 2.g

Key:

Ratiometric pressure transducer – evaporation pressure

NTC – suction temperature

Digital input to enable control

Personal computer for conﬁguration

USB / tLAN converter

2.4 Installation

For installation, proceed as shown below, with reference to the wiring

diagrams and the technical speciﬁcations table:

1. connect the probes: these can be installed up to a maximum

distance of 10 m from the driver; select the pressure probe suitable

for the refrigerant. For details on the recommended pressure probe

for each refrigerant, see “Commissioning”;

2. connect any digital inputs, maximum length 10 m;

3. connect the valve cable: it is recommended to use a maximum cable

length of 1 m for E2V and E3V valves.

4. the 24 V models can be powered at:

• 24 Vac: use a class II safety transformer, adequately protected against

short-circuits and overload. Transformer power must be between

20 and 50 VA, as shown in the technical speciﬁcations table;

• 24 Vdc: use an external power supply, the see technical

speciﬁcations table;

5. the connection cables must have a minimum cross-section of 0.35 mm

;

6. power on the driver: the LED on the power supply/display comes

on and the driver will be immediately operational, with the default

parameters:

a. Refrigerant = R404A;

b. Type of control: multiplexed showcase/cold room;

c. Superheat set point = 11 K.

7. program the driver, if necessary: see the “User interface” chapter;

8. connect to the serial network where required. See the following diagrams

for connecting the earth on the 24 V EVD mini models.

EVD mini 24 Vac in serial network

Case 1: multiple drivers connected in a network, inside the same electrical

panel, powered by the same transformer

GND

Tx/Rx+

Tx/Rx-

GND

Tx/Rx+

Tx/Rx-

230 Vac

24 Vac

pCO

Fig. 2.h

Case 2: multiple drivers connected in a network, inside diﬀerent electrical

panels with the same earth point

GND

Tx/Rx+

Tx/Rx-

20 VA

230 Vac

24 Vac

GND

Tx/Rx+

Tx/Rx-

20 VA

230 Vac

24 Vac

pCO

Fig. 2.i

Important: Earthing of G0 and G in driver EVD mini 24 Vac

connected in serial network brings to permanent damage of the driver.

GND

Tx/Rx+

Tx/Rx-

20 VA

230 Vac

24 Vac

GND

Tx/Rx+

Tx/Rx-

20 VA

230 Vac

24 Vac

pCO

NO!

Fig. 2.j

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

Installation environment

Important: avoid installing the drivers in environments with the

following characteristics:

• relative humidity greater than 90% or with condensation;

• strong vibrations or knocks;

• exposure to continuous water sprays;

• exposure to aggressive and polluting atmospheres (e.g.: sulphur

and ammonia fumes, saline mist, smoke) to avoid corrosion and/or

oxidation;

• strong magnetic and/or radio frequency interference (therefore avoid

installing the devices near transmitting antennae);

• exposure of the driver to direct sunlight and to the elements in general.

Important: the following warnings must be observed when

connecting the driver:

• if the driver is used in a way that is not speciﬁed in this user manual,

protection cannot be guaranteed;

• incorrect power connections may seriously damage the driver;

• use cable ends suitable for the corresponding terminals. Loosen each

screw and insert the cable ends, then tighten the screws and gently

tug the cables to check they are suﬃciently tight;

• separate as much as possible (at least 3 cm) the probe and digital

input cables from power cables to avoid possible electromagnetic

disturbance. Never run power cables (including the electrical panel

cables) and probe signal cables in the same conduits;

• do not run probe signal cables in the immediate vicinity of power

devices (contactors, circuit breakers, etc.). Reduce the path of probe

cables as much as possible, and avoid spiral paths that enclose power

devices;

• avoid powering the controller directly from the main power supply in

the panel if this supplies diﬀerent devices, such as contactors, solenoid

valves, etc., which will require a separate transformer;

• *EVD mini/ice is a controller to be incorporated into the ﬁnal

equipment; it must not be wall-mounted;

• * DIN VDE 0100: protective separation must be guaranteed between

the SELV circuits (Safety Extra Low Voltage) and the other circuits. The

requirements of DIN VDE 0100 must be complied with. To prevent

disruption of the protective separation (between the SELV circuits and

the other circuits) ensure additional fastening near the terminations.

This additional fastening must secure the insulation and not the wires.

2.5 Copy parameters with programming key

Note:

• The parameters must only be copied when the driver is NOT powered;

• also see the programming key technical leaﬂet, P/N +050003930.

Procedure:

A. Open the cover on the key using a screwdriver;

B. Set the microswitches based on the operation :

- UPLOAD: microswitches 2 = OFF,

- DOWNLOAD: microswitches 1= OFF,

microswitches 2 = ON

See leaﬂet +050003930

Fig. 2.k

EVD mini (24 V)

Important: do not use a screwdriver to remove the cover on the

display, to avoid damaging the board.

To remove the cover of the display:

Apply a pressure rightward on the left side of the cover.

Raise up the right side to extract it.

Plug the key into the provided connector, then perform the desired

operation (UPLOAD/DOWNLOAD).

GAS

ype

Mode

Super Heat

press

GAS Type

Mode

Super Heat

Fig. 2.l

EVD mini (230 V)

To remove the cover of the display:

Press with a screwdriver as shown in the ﬁgure, to remove the cover.

Lift the cover and remove it.

Plug the key into the provided connector, then perform the

desired operation (UPLOAD/DOWNLOAD).

GAS

ype

Mode

Super Heat

GAS T

ype

Mode

Super He

press

Fig. 2.m

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

3. USER INTERFACE

On models where featured, the user interface comprises the two-

digit display and keypad with three buttons that, pressed alone or in

combination, are used to perform all the conﬁguration and programming

operations on the driver.

Model without display

Fig. 3.a

Red LED - see “Alarms”

Green LED - power supply ON

Model with display

GAS Type

Mode

Super Heat

Fig. 3.b

Key

Parameter label (for commissioning)

Keypad

Control ON/OFF digital input status LED

ﬂashing/oﬀ = DI closed/open (*)

Two-digit display

(*) when the digital input is closed, the LED ﬂashes and control is activated.

During commissioning/setup, the parameter label shows the meaning

of the segments displayed in the ﬁrst digit, corresponding to the three

parameters being set:

A. GAS Type: type of refrigerant;

B. Mode: operating mode;

C. Superheat: superheat set point.

See the “Commissioning” chapter.

GAS Type

Mode

Super Heat

GAS Type

Mode

Super Heat

GAS Type

Mode

Super Heat

A. Refrigerant B. Mode (operating mode) C. Superheat set point

3.1 Keypad

Key Description

UP DOWN

• Increases/decreases the value of the set point or other

selected parameter

• menu navigation

PRG/Set

• at the end of the commissioning procedure, press for 2 s to

exit and activate control;

• enter/exit control mode, saving the parameters;

• reset alarm E8

Tab. 3.b

3.2 Display

During normal operation, the two-digit display shows the superheat

measure and any alarms. If used as an analogue positioner, it displays

the 0 to 10 V input value with decimal point. The display interval for the

superheat value is -5 to 55 K (-9 to 99 °F). In general, values between -99

and 999 are displayed as follows:

1. values from 0 to 10 are displayed with decimal point and decimals;

2. values greater than 99 are displayed in two steps:

- ﬁrst, the hundreds, followed by “H”

- then the tens and units.

3. values less than -9 are displayed in two steps:

- ﬁrst the “-“sign;

- then the tens and units.

GAS Type

Mode

Super Heat

GAS Type

Mode

Super Heat

123 --->

GAS Type

Mode

Super Heat

GAS Type

Mode

Super Heat

-99 --->

Fig. 3.c

3.3 Programming mode

The parameters can be modiﬁed using the front keypad. Access depends

on the user level: basic parameters (ﬁrst conﬁguration/setup) and Service

parameters (Installer).

Important: DO NOT change the control parameters before

completing the commissioning wizard, as described in chapter 4.

Modifying the Service parameters

The Service parameters include, in addition to the parameters for the

conﬁguration of input S1, those corresponding to the network address,

probe readings, protectors and manual positioning. See the param. table.

Procedure:

1. press UP and DOWN together and hold for more than 5 s: the ﬁrst

parameter is displayed: P1 = probe S1 reading;

2. press UP/ DOWN until reaching the desired parameter;

3. press PRG/ Set to display the value;

4. press UP/ DOWN to modify the value;

5. press PRG/ Set to conﬁrm and return to the parameter code;

6. repeat steps 2 to 5 to modify other parameters;

7. (when the parameter code is displayed) press PRG/Set and hold for

more than 2 s to exit the parameter setting procedure.

GAS Type

Mode

Super Heat

Fig. 3.d

Note: if no button is pressed, after around 30 s the display

automatically returns to standard visualisation.

3.4 Restore factory parameters (default)

It is possible restore the controller to the default settings.

Procedure:

with the controller in standard display mode, press the

three buttons together. After 5 seconds the display shows “rS”. The reset

procedure can

be conﬁrmed within 10 seconds, by pressing PRG/SET buttons

for 3 seconds. If no button is pressed during this time, the procedure will

be cancelled. At the end, the controller displays two dashes and then

awaits the commissioning parameters.

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

4. COMMISSIONING

Note:

• If the controller does not have a display, see “Network connection”;

• the default pressure probe is the ratiometric probe, with a measurement

range of -1…9.3 barg;

• note the unit of measure (K/°F) when setting the superheat set point. To

change the unit of measure, see the “Functions” chapter.

4.1 Commissioning procedure

Once the electrical connections have been completed (see the chapter

“Installation”) and the power supply has been connected, the operations

required for commissioning the driver depend on the type of interface

used, however essentially involve setting just 3 parameters: refrigerant,

functioning mode, superheat setpoint.

Important:

• until the commissioning procedure has been completed, control will

not be active;

• (only during commissioning) changing the refrigerant also means

having to change the type of pressure probe.

Power on the driver: the display lights up and the driver awaits the

commissioning parameters, as indicated by the bar on the display:

1. Refrigerant (default = 3: R404A);

2. Type of control (default = 1: multiplexed showcase/cold room);

3. Superheat set point (default= 11 K).

Procedure:

GAS Type

Mode

Super Heat

1. The display shows the bar at the top: refrigerant (GAS Type)

GAS Type

Mode

Super Heat

2. Press PRG/Set to display the refrigerant setting

GAS Type

Mode

Super Heat

3. Press UP/DOWN to modify the value

GAS Type

Mode

Super Heat

4. Press PRG to save the setting and return to the refrigerant parameter

code (bar at top)

GAS Type

Mode

Super Heat

5. Press DOWN to move to the next parameter: Mode, indicated by the

bar in the middle.

6. Repeat steps 2-4 to set superheat settings 1-7 and bypass 8-9;

GAS Type

Mode

Super Heat

7. Press DOWN to move to the next parameter. For the superheat set

point, the bar at the bottom is shown. Set the superheat set point;

GAS Type

Mode

Super Heat

8. In the event of bypass control by pressure, parameter _P is shown.

Set the bypass pressure set point.

GAS Type

Mode

Super Heat

9. In the event of bypass control by temperature, parameter _t is

shown. Set the bypass temperature set point.

GAS Type

Mode

Super Heat

10. Press PRG/Set for 2 s to save the settings, exit programming mode

and activate control. The standard display is shown.

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

4.5 Initial conﬁguration parameters

Important: ONLY DURING COMMISSIONING, changing the

refrigerant also means having to change the type of ratiometric probe;

if not speciﬁed in the table, the ratiometric probe type is (-1 ... 9.3 barg).

Refrigerant

Parameter/ description Def.

Gas Type = refrigerant

0 = Custom

1 R22 15 R422D 29 R455A (-1...12.8 barg)

2 R134a 16 R413A 30 R170 (0...17.3 barg)

3 R404A 17 R422A 31 R442A (-1...12.8 barg)

4 R407C 18 R423A 32 R447A (-1...12.8 barg)

5 R410A 19 R407A 33 R448A

6 R507A 20 R427A 34 R449A

7 R290 21 R245FA 35 R450A (-1...4.2 barg)

8 R600

(-1...4.2 barg)

22 R407F 36 R452A (-1...12.8 barg)

9 R600a

(-1...4.2 barg)

23 R32

(0...17.3 barg)

37 R508B (-1...4.2 barg)

10 R717 24 HTR01 38 R452B

11 R744

(0...45 barg)

25 HTR02 39 R513A (-1...4.2 barg)

12 R728 26 R23 40 R454B

13 R1270 27 R1234yf

14 R417A 28 R1234ze (-1...4.2

barg)

3 =

R404A

Note: if the refrigerant gas is not among those selectable for the

“GAS Type = refrigerant” parameter:

1. set any refrigerant (e.g. R404);

2. select the type of main control, the superheat set point and complete

the initial commissioning procedure;

3. use the VPM program (Visual Parameter Manager, see the chapter

“Network connection”) and set the type of refrigerant: “0 = custom”

and the “Dew point a...f high/low” parameters that deﬁne the

refrigerant;

4. start control, for example by closing the digital input contact.

Operating mode

Mode = Operating mode

1 Multiplexed showcase/cold room

2 Air-conditioner/chiller with plate heat exchanger

3 Air-conditioner/chiller with tube bundle heat exchanger

4 Air-conditioner/chiller with ﬁnned coil heat exchanger

5 Analogue positioner (0 to 10 V)

6 Superheat control with 2 temperature probes

7 Subcritical CO2 showcase/cold room

8 Hot gas bypass by pressure

9 Hot gas bypass by temperature

1 = Mul-

tiplexed

showcase/

cold room

Set point

Note: take into consideration the unit of measure (K/°F) when

setting the superheat set point.

Superheat set point 11 K(20°F)

Bypass pressure set point 3 bar

Bypass temperature set point 10 °C

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

5. FUNCTIONS

The valve must therefore be closed further. The operating range of the

superheat temperature is limited at the lower end: if the ﬂow-rate through

the valve is excessive the superheat measured will be near 0 K. This indicates

the presence of liquid, even if the percentage of this relative to the gas

cannot be quantiﬁed. There is therefore un undetermined risk to the

compressor that must be avoided. Moreover, a high superheat temperature

as mentioned corresponds to an insuﬃcient ﬂow-rate of refrigerant. The

superheat temperature must therefore always be greater than 0 K and have

a minimum stable value allowed by the valve-unit system.

A low superheat temperature in fact corresponds to a situation of probable

instability due to the turbulent evaporation process approaching the

measurement point of the probes. The expansion valve must therefore

be controlled with extreme precision and a reaction capacity around

the superheat set point, which will almost always vary from 3 to 14 K.

Set point values outside of this range are quite infrequent and relate to

special applications.

5.1 Control

EVD mini is a superheat controller and can be used as an analogue

positioner. The type of refrigeration unit can be selected using the

“Operating mode” parameter.

Parameter/description Def.

Operating mode

1 Multiplexed cabinet/cold room

2 Air-conditioner/chiller with plate heat exchanger

3 Air-conditioner/chiller with tube bundle heat exchanger

4 Air-conditioner/chiller with ﬁnned coil heat exchanger

5 Analogue positioner (0 to 10 V)

6 Superheat control with 2 temperature probes

7 Subcritical CO2 showcase/cold room

8 Hot gas bypass by pressure

9 Hot gas bypass by temperature

1 = multiplexed

cabinet/cold room

Tab. 5.a

Based on the operating mode setting , the driver automatically sets a

series of control parameters.

Operating mode PID:

proport.

gain

PID:

integra-

tion time

Super-

heat

set

point

LowSH protec-

tion

LOP protection MOP protection Bypass

pres-

sione:

setpoint

(bar)

Bypass

tempe-

ratura:

setpoint

(°C)

th-

reshold

Integra-

tion time

th-

reshold

Integra-

tion time

th-

reshold

Integra-

tion time

1 Multiplexed cabinet/cold room 15 150 11 5 15 -50 0 50 20

2 Air-conditioner/chiller with plate heat exchanger 3 40 6 2 2,5 -50 4 50 10

3 Air-conditioner/chiller with tube bundle heat

exchanger

5 60 6 2 2,5 -50 4 50 10

4 Air-conditioner/chiller with ﬁnned coil heat

exchanger

10 100 6 2 10 -50 10 50 20

5 Analogue positioner (0 to 10 V) - - - - - - - - -

6 Superheat control with 2 temperature probes 15 150 11 5 15 -50 0 50 20

Subcritical CO2 showcase/cold room

20 400 13 7 15 -50 0 50 20

Hot gas bypass by pressure

20 200 - - - - - - - 3 -

Hot gas bypass by temperature

15 150 - - - - - - - - 10

Tab. 5.b

Superheat

The primary purpose of the electronic valve is ensure that the ﬂow-rate

of refrigerant that ﬂows through the nozzle corresponds to the ﬂow-rate

required by the compressor. In this way, the evaporation process will take

place along the entire length of the evaporator and there will be no liquid

at the outlet (consequently in the branch that runs to the compressor). As

liquid is not compressible, it may cause damage to the compressor and even

breakage if the quantity is considerable and the situation lasts some time.

Superheat control

The parameter that the control of the electronic valve is based on is

the superheat temperature, which eﬀectively tells whether or not there

is liquid at the end of the evaporator. The superheat temperature is

calculated as the diﬀerence between: superheated gas temperature

(measured by a temperature probe located at the end of the evaporator)

and the saturated evaporation temperature (calculated based on the

reading of a pressure transducer located at the end of the evaporator and

using the Tsat(P) conversion curve for each refrigerant).

Superheat = Superheated gas temperature

(*)

– Saturated evaporation

temperature

(*) suction

If the superheat temperature is high it means that the evaporation

process is completed well before the end of the evaporator, and therefore

ﬂow-rate of refrigerant through the valve is insuﬃcient. This causes a

reduction in cooling eﬃciency due to the failure to exploit part of the

evaporator. The valve must therefore be opened further.

Vice-versa, if the superheat temperature is low it means that the evaporation

process has not concluded at the end of the evaporator and a certain quantity

of liquid will still be present at the inlet to the compressor.

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

EVD mini

Fig. 5.a

Key

CP compressor EEV electronic expansion valve

C condenser V solenoid valve

L liquid receiver E evaporator

F dewatering ﬁlter P pressure probe (transducer)

S liquid indicator T temperature probe

For the wiring, see “Wiring description”.

PID parameters

Superheat control uses a PID algorithm. The control output is calculated

as the sum of separate contributions: proportional and integral.

• the proportional action opens or closes the valve proportionally to

the variation in the superheat temperature. Thus the greater the K

(proportional gain) the higher the response speed of the valve. The

proportional action does not consider the superheat set point, but

rather only reacts to variations. Therefore if the superheat value does

not vary signiﬁcantly, the valve will essentially remain stationary and

the set point cannot be reached;

• the integral action is linked to time and moves the valve in proportion

to the deviation of the superheat value from the set point. The greater

the deviations, the more intense the integral action; in addition, the

lower the value of Ti (integral time), the more intense the action

will be. The integral time, in summary, represents the intensity of the

reaction of the valve, especially when the superheat value is not near

the set point.

See the “EEV system guide” +030220810 for further information on

calibrating PID control.

Par. Description Def. Min. Max. UoM

Superheat Superheat set point

11(20)

LowSH: threshold 55 (99) K(°F)

PID proport. gain 15 0 800 -

PID integral time 150 0 999 s

Note: when selecting the type of Mode, the PID control values

suggested by CAREL will be automatically set for each application.

Control parameters for protection functions

See chapter on “Protectors”.

5.2 Analogue positioner (0-10 Vdc)

The valve will be positioned linearly depending on the value of the “0

to 10 V input for analogue valve positioning” read by input S2. There

is no PID control nor any protection (LowSH, LOP, MOP), and no valve

unblock procedure. The opening of digital input DI stops control, and

consequently forces the valve closed, switching operation to standby.

0 ...10 Vdc

regulator

010

Vdc

100%

EVD mini

Fig. 5.b

Key:

EV Electronic valve A Valve opening

For the wiring see chap. 2: “Description of the terminals”.

Important: the pre-positioning and re-positioning procedures will

not be performed. Manual positioning can in any case be enabled when

control is active or in standby.

5.3 Superheat control with 2 temp. probes

The functional diagram is shown below. This type of control must be used

with care, due to the lower precision of the temperature probe compared

to the probe that measures the saturated evaporation pressure.

Parameter/ description Def.

Mode = Operating mode

… 6 = Superheat control with 2 temperature

probes

1 = Multiplexed showcase/

cold room

EVD mini

Fig. 5.e

Key:

CP Compressor V Solenoid valve

C Condenser S Liquid indicator

L Liquid receiver EV Electronic valve

F Dewatering ﬁlter E Evaporator

T Temperature probe S1 Evaporation temperature probe

S2 Suction temperature probe

For the wiring see chap. 2: “Description of the terminals”.

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

Par. Description Def Min Max UOM

Superheat Superheat set point 11(20) LowSH:

thresh.

55(99) K

CP PID: proportional gain 15 0 800 -

ti PID: integral time 150 0 999 s

5.4 Special functions

Hot gas bypass by pressure

This function can be used for cooling capacity control. If there is no

request from circuit B, the compressor suction pressure decreases and

the bypass valve opens, so as to deliver more hot gas and decrease circuit

capacity.

V1 V2

M T

V1 V2

M T

EVD mini

Key

CP compressor V1 solenoid valve

C condenser V2 thermostatic expansion valve

L liquid receiver EV electronic valve

F ﬁlter-drier E evaporator

S liquid sightglass

For the wiring see the “General connection diagram”.

This is PID without any protection (LowSH, LOP, MOP, see the chapter

on Protectors), no valve unblock procedure and no auxiliary control

functions. The function uses the hot gas bypass pressure probe read

by input S1, compared against the “Hot gas bypass pressure set point”.

Control is reverse: as the pressure increases, the valve closes and vice-

versa.

Par. Description Def Min Max UOM

_P Hot gas bypass pressure

set point

3 -20(290) 200(2900) bar(psig)

CP PID: proportional gain 15 0 800 -

ti PID: integral time 150 0 999 s

Hot gas bypass by temperaturs

This function can be used for cooling capacity control. On a showcase, if

the room temperature probe detects an increase in temperature, cooling

capacity needs to increase, so the valve must close.

V1 V2

M T

LEV

EVD mini

Key

CP compressor V1 solenoid valve

C condenser V2 thermostatic expansion valve

L liquid receiver EV electronic valve

F ﬁlter-drier E evaporator

S liquid sightglass

For the wiring see the “General connection diagram”.

This is PID without any protection (LowSH, LOP, MOP, see the chapter

on Protectors), no valve unblock procedure and no auxiliary control

functions. The function uses the hot gas bypass temperature probe

read by input S2, compared against the “Hot gas bypass temperature set

point”. Control is reverse: as the temperature increases, the valve closes

and vice-versa.

Par. Description Def Min Max UOM

_t Hot gas bypass tempera-

ture set point

10 -85(-121) 200(392) °C(°F)

CP PID: proportional gain 15 0 800 -

ti PID: integral time 150 0 999 s

5.5 Special control function: smooth lines

Note: the Smooth_line parameter is only accessible via the

supervisor.

The smooth lines function optimises evaporator capacity based on actual

cooling demand, allowing more eﬀective and stable control. The function

completely eliminates traditional on/oﬀ control cycles, modulating the

temperature exclusively using the electronic valve; superheat set point

is controlled through a precise PI control algorithm based on the actual

control temperature.

The master controller (connected via serial to EVD mini), through

dynamic management of the Smooth_line parameter, modiﬁes the

superheat set point for management of the electronic expansion valve,

from a minimum (SH_SET) to a maximum (SH_SET + Smooth_line): this

consequently acts directly on the PID control algorithm that modiﬁes the

valve position. This is useful when the control temperature approaches

the set point; the Smooth_line parameter is used to prevent the valve

from closing, by reducing the evaporator’s cooling capacity.

In order to use this function, the digital input must be conﬁgured as

BACKUP. The Smooth_line parameter thus allows the control set point to

be adjusted instantly.

In the event where there is no network connection, the Smooth_line

parameter is reset so as to resume normal control (START/STOP from

digital input and SH_SET as the superheat set point).

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

The main eﬀects are:

• no swings in temperature and superheat due to the set point being

reached;

• stable temperature and superheat control;

• maximum energy savings due to load stabilisation.

Par. Description Def. Min. Max. UOM

DI conﬁguration

1=start/stop - 2=control backup

11 2 -

Smooth_line

A: superheat set point oﬀset for

smooth lines

0 -99

(-55)

(55)

K/°F

Temp. set

SH set

SH_set+

Smooth_line

Key

SH set Superheat set point t time

Temp.set Temperature set point

Note: the temperature setting based on the corresponding set

point is managed by the master controller, while superheat control is

managed by the EVD mini.

5.6 Control parameters for protection

functions

See chapter on “Protectors”.

5.7 Service parameters

The other conﬁguration parameters, to be set where necessary before

starting the controller, concern:

• the type of ratiometric pressure/temperature probe;

• the serial address for network connection;

• the type of unit of measure;

• enabling change in type of control (Mode);

• the number of steps (480/960) to control valve position.

Type of pressure/temperature probe (par. S1)

S1 is used to select the type of ratiometric pressure or NTC probe.

Par. Description Def. Min. Max. UOM

S1 Type of probe S1

1 = -1…4.2 barg

2 = 0.4…9.3 barg

3 = -1…9.3 barg

4 = 0…17.3 barg

5 = 0.85…34.2 barg

6 = 0…34.5 barg

7 = 0…45 barg

8 = -1…12.8 barg

9 = 0…20.7 barg

10 = 1.86…43.0 barg

11 = NTC (-50…105°C)

12 = Ratiometric (OUT=0-5V) 0-60 barg

13 = Ratiometric (OUT=0-5V) 0-90 barg

14 = Remote pressure probe from RS485

3111-

Note: the maximum and minimum limits for the pressure probe

alarm can be set. See the parameter table.

Network address (par. n1)

See chap. “Network connection”

Unit of measure (par. Si)

The unit of measure used by the driver can be selected:

• S.I. (°C, K, barg);

• Imperial (°F, psig).

Par. Description Def. Min. Max. UOM

Si Unit of measure

1=°C/K/barg

2=°F/psig

112-

Note: lthe unit of measure K or °F relates to degrees Kelvin or

Fahrenheit adopted for measuring the superheat and the related

parameters.

When changing the unit of measure, all the values of the parameters

saved on the driver and all the measurements read by the probes will

be recalculated. This means that when changing the units of measure,

control remains unaltered.

Example 1: The pressure read is 20 barg, this will be immediately

converted to the corresponding value of 290 psig.

Example 2: The “superheat set point” parameter set to 10 K will be

immediately converted to the corresponding value of 18 °F.

Access to Mode parameter (par. IA)

To avoid accidental modiﬁcation of the controller’s operating mode, it

is possible to disable the access to the corresponding mode parameter

(mode).

Par. Description Def. Min. Max. UOM

IA Enable operating mode modiﬁcation

0/1 = yes/ no

001-

Number of control steps (par. U3)

Total number of steps between the valve fully closed and fully open

position

Par. Description Def. Min. Max. UOM

U3 Number of valve control steps

1 / 2 = 480/960 steps

112-

Digital input

The digital input function can be set by parameter:

Par. Description Def. Min. Max. UOM

di DI conﬁguration

1=Start/stop control;

2=Control backup

112-

Start/Stop control:

• digital input closed: control activated;

• digital input open: driver in standby (see paragraph “Control status”);

Important: this setting excludes activation/deactivation of control

from the network. See the next setting.

Control backup: when connected to a network, in the event of

communication failures, the driver veriﬁes the status of the digital input

to determine whether control is activated or in standby.

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

6. PROTECTORS

These are additional functions that are activated in speciﬁc situations that

are potentially dangerous for the unit being controlled. They feature an

integral action, that is, the action increases gradually when moving away

from the activation threshold. They may add to or overlap (disabling)

normal PID superheat control. By separating the management of these

functions from PID control, the parameters can be set separately, allowing,

for example, normal control that is less reactive yet much faster in

responding when exceeding the activation limits of one of the protectors.

6.1 Protectors

The protectors are 3:

• LowSH, low superheat;

• LOP, low evaporation temperature;

• MOP, high evaporation temperature;

The protectors have the following main features:

• activation threshold: depending on the operating conditions of the

controlled unit, this is set in Service programming mode;

• integration time, which determines the intensity (if set to 0, the

protector is disabled): set automatically based on the type of main

control;

• alarm, with activation threshold (the same as the protector) and

timeout (if set to 0 disables the alarm signal).

Note: The alarm signal is independent from the eﬀectiveness of

the protector, and only signals that the corresponding threshold has

been exceeded. If a protector is disabled (null integration time), the

relative alarm signal is also disabled.

Each protector is inﬂuenced by the proportional gain parameter (CP) of

PID superheat control. The higher is the value of CP, the more intensely

the protection will react.

Characteristics of the protectors

Protection Reaction Reset

LowSH Intense closing Immediate

LOP Intense opening Immediate

MOP Moderate closing Controlled

Tab. 6.a

Reaction: summary description of the type of action in controlling the

valve.

Reset: summary description of the type of reset following the activation

of the protector. Reset is controlled to avoid swings around the activation

threshold or immediate reactivation of the protector.

Note: all the alarms are generated after a ﬁxed delay, as shown in

the table:

Protectors Delay (s)

LowSH 300

LOP 300

MOP 600

LowSH (low superheat)

The protector is activated so as to prevent the low superheat from

causing the return of liquid to the compressor.

Par. Description Def. Min. Max. U.M.

C1 LowSH protection: threshold 5(9) -5(-9) Set point

superheat

K(°F)

C2 LowSH protection: integration time 15 0 800 s

When the superheat value falls below the threshold, the system enters low

superheat status, and the intensity with which the valve is closed is increased:

the more the superheat falls below the threshold, the more intensely the valve

will close. The LowSH threshold must be less than or equal to the superheat

set point. The low superheat integration time indicates the intensity of the

action: the lower the value, the more intense the action.

The integration time is set automatically based on the type of

main control.

OFF

Low_SH

Low_SH_TH

Fig. 6.a

key:

SH Superheat A Alarm

Low_SH_TH Low_SH protection threshold D Alarm delay

Low_SH Low_SH protection t Time

B Alarm automatic reset

LOP (low evaporation pressure)

LOP= Low Operating Pressure

The LOP protection threshold is applied as a saturated evaporation

temperature value so that it can be easily compared against the technical

speciﬁcations supplied by the manufacturers of the compressors. The

protector is activated so as to prevent too low evaporation temperatures

from stopping the compressor due to the activation of the low pressure

switch. The protector is very useful in units with compressors on board

(especially multi-stage), where when starting or increasing capacity the

evaporation temperature tends to drop suddenly.

When the evaporation temperature falls below the low evaporation

temperature threshold, the system enters LOP status and is the intensity

with which the valve is opened is increased. The further the temperature

falls below the threshold, the more intensely the valve will open. The

integration time indicates the intensity of the action: the lower the value,

the more intense the action.

Par. Description Def. Min. Max. U.M.

C3 LOP protection: threshold -50

(-58)

-85

(-121)

MOP protec.:

threshold

C(°F)

C4 LOP protection: integration time 0 0 800 s

The integration time is set automatically based on the type of main

control.

Note:

• the LOP threshold must be lower then the rated evaporation

temperature of the unit, otherwise it would be activated unnecessarily,

and greater than the calibration of the low pressure switch, otherwise

it would be useless. As an initial approximation it can be set to a value

exactly half-way between the two limits indicated;

• the protector has no purpose in multiplexed systems (showcases)

where the evaporation is kept constant and the status of the individual

electronic valve does not aﬀect the pressure value;

• the LOP alarm can be used as an alarm to highlight refrigerant leaks by

the circuit. A refrigerant leak in fact causes an abnormal lowering of the

evaporation temperature that is proportional, in terms of speed and

extent, to the amount of refrigerant dispersed.

ENG

“EVD mini” +0300036EN - rel. 1.2 - 23.04.2018

OFF

ALARM

OFF

LOP

LOP_TH

T_EVAP

Fig. 6.b

Key:

T_EVAP Evaporation temperature D Alarm timeout

LOP_TH Low evaporation temperature

protection

ALARM Alarm

LOP LOP protection t Time

B Automatic alarm reset

MOP (high evaporation pressure)

MOP= Maximum Operating Pressure.

The MOP protection threshold is applied as a saturated evaporation

temperature value so that it can be easily compared against the technical

speciﬁcations supplied by the manufacturers of the compressors. The

protector is activated so as to prevent too high evaporation temperatures

from causing an excessive workload for the compressor, with consequent

overheating of the motor and possible activation of the thermal protector.

The protector is very useful in self-contained units if starting with a high

refrigerant charge or when there are sudden variations in the load. The

protector is also useful in multiplexed systems (showcases), as allows all

the utilities to be enabled at the same time without causing problems

of high pressure for the compressors. To reduce the evaporation

temperature, the output of the refrigeration unit needs to be decreased.

This can be done by controlled closing of the electronic valve, implying

superheat is no longer controlled, and an increase in the superheat

temperature. The protector will thus have a moderate reaction that tends

to limit the increase in the evaporation temperature, keeping it below the

activation threshold while trying to stop the superheat from increasing

as much as possible. Normal operating conditions will not resume based

on the activation of the protector, but rather on the reduction in the

refrigerant charge that caused the increase in temperature. The system

will therefore remain in the best operating conditions (a little below the

threshold) until the load conditions change.

Par. Description Def. Min. Max. U.M.

C5 MOP protection threshold 50

(122)

Protection LOP:

threshold

200

(392)

C(°F)

C6 MOP protection integration

time

20 0 800 s

The integration time is set automatically based on the type of main

control.

When the evaporation temperature rises above the MOP threshold, the

system enters MOP status, superheat control is interrupted to allow the

pressure to be controlled, and the valve closes slowly, trying to limit the

evaporation temperature.

As the action is integral, it depends directly on the diﬀerence between

the evaporation temperature and the activation threshold. The more the

evaporation temperature increases with reference to the MOP threshold,

the more intensely the valve will close. The integration time indicates the

intensity of the action: the lower the value, the more intense the action.

OFF

ALARM

OFF

PID

OFF

MOP

MOP_TH - 1

MOP_TH

T_EVAP

Fig. 6.c

Key:

T_EVAP Evaporation temperature MOP_TH MOP threshold

PID PID superheat control ALARM Alarm

MOP MOP protection t Time

D Alarm timeout

Important: the MOP threshold must be greater than the rated

evaporation temperature of the unit, otherwise it would be activated

unnecessarily. The MOP threshold is often supplied by the manufacturer

of the compressor. It is usually between 10 °C and 15 °C.

If the closing of the valve also causes an excessive increase in the suction

temperature (S2) above the set threshold – set via parameter (C7), not

on the display - the valve will be stopped to prevent overheating the

compressor windings, awaiting a reduction in the refrigerant charge. If

the MOP protection function is disabled by setting the integral time to

zero, the maximum suction temperature control is also deactivated.

Par. Description Def. Min. Max. U.M.

C7 MOP protection: disabling threshold

(86)

-85

(-121)

200

(392)

°C (°F)

At the end of the MOP protection function, superheat regulation restarts

in a controlled manner to prevent the evaporation temperature from

exceeding the threshold again.

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Carel EVD mini User manual

Brand: Carel

Model: EVD mini

Category: Measuring, testing & control

Type: User manual

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Carel EVD mini User manual

Carel EVD mini User manual

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