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EVD mini

Carel EVD mini User manual

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High Efficiency Solutions
EVD mini
NO POWER
& SIGNAL
CABLES
TOGETHER
READ CAREFULLY IN THE TEXT!
User manual
Superheat control for unipolar electronic
expansion valve
3
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!
5
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
7
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
8
GAS Type
Mode
Super Heat
72
(2.8)
88 (3.5)
98
(3.9)
95
(3.7)
60 (2.4)
33 (1.3)
BASSO/ BOTTOM
BASSO/ BOTTOM
74,1 (2.9)
87
(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
T
ype
Mode
Super He
a
t
2
1
2
A
A
GAS
Type
Mode
Super He
at
74,10 (2.9)
72 (2.8)
Ø 4 (0.2)
GAS Type
Mode
Super Hea
t
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
A
;
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
9
GAS Type
Mode
Super Heat
GND
Tx/Rx+
Tx/Rx-
G
G0
DI
GND
5Vref
Signal
S1
S2
GND
Signal
+13V (in)
+13V (out)
GND
RS485
Modbus®
CVSTDUM0R0
pCO
ratiometric pressue
transducer
NTC
shield
shield
Ferrite/ Ferrite bead
cod. 0907879AXX
PC
VPM
ULTRACAP
Module
1
3
NTC
NTC
S1
S2
S1
S2
A B C D
E
F
G
1
2
0,3 Nm
CAREL E2 V/ E3V
unipolar valve
digital input to start
the regulation
24 Vdc
G
G0
20 VA
230 Vac
24 Vac
G
G0
H1
H2
GAS Type
Mode
Super Heat
S2 S1
GND
Tx/Rx+
Tx/Rx-
RS485
Modbus®
CVSTDUM0R0
pCO
shield
shield
PC
VPM
1
D I
N
L
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
1
3
A
B
C D
ratiometric pressue
transducer
NTC
NTC
S1
S2
S1
S2
E
F
G
H3
1
2
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
A
ExV Single-pole valve connection
H2
(24 Vdc
power
supply)
G Power supply, 24 Vdc
B
+13 V (in)
Ultracap module connection (accessory)
G0 Power supply, 0 Vdc
+13 V (out) DI Digital input to enable control
GND
H3
(230 V
power
supply)
L 230 V power supply, line
C
Signal S2 probe (temperature) N 230 V power supply, neutral
Ground Earth for S2 probe DI 230 V digital input to enable control
D
GND Earth for S1 probe
G
GND
Terminal for RS485 connection5Vref Power S1 active probe Tx/ Rx +
Signal S1 probe: pressure or temperature Tx/ Rx -
E
- Connection as positioner (0 to 10 V input)
1
PC for configuration
F
-
Connection for superheat control with 2 temperatu-
re probes
2
USB – RS485 Converter
H1
(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
10
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-
G
G0
DI
S1
S2
CVSTDUM0R0
PC
VPM
2 1
4
5
0,3 Nm
CAREL E2 V/ E3V
unipolar valve
digital input to start
the regulation
24 Vdc
G
G0
20 VA
230 Vac
24 Vac
G
G0
3
Fig. 2.g
Key:
1
Ratiometric pressure transducer – evaporation pressure
2
NTC – suction temperature
3
Digital input to enable control
4
Personal computer for configuration
5
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
2
;
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-
G
G0
DI
GND
Tx/Rx+
Tx/Rx-
G
G0
DI
230 Vac
24 Vac
pCO
PC
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-
G
G0
DI
20 VA
230 Vac
24 Vac
GND
Tx/Rx+
Tx/Rx-
G
G0
DI
20 VA
230 Vac
24 Vac
pCO
PC
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-
G
G0
DI
20 VA
230 Vac
24 Vac
GND
Tx/Rx+
Tx/Rx-
G
G0
DI
20 VA
230 Vac
24 Vac
pCO
PC
NO!
Fig. 2.j
11
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
A
B
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:
1
Apply a pressure rightward on the left side of the cover.
2
Raise up the right side to extract it.
3
Plug the key into the provided connector, then perform the desired
operation (UPLOAD/DOWNLOAD).
GAS
T
ype
Mode
Super Heat
press
L
press
GAS Type
Mode
Super Heat
1
2
3
Fig. 2.l
EVD mini (230 V)
To remove the cover of the display:
1
Press with a screwdriver as shown in the figure, to remove the cover.
2
Lift the cover and remove it.
3
Plug the key into the provided connector, then perform the
desired operation (UPLOAD/DOWNLOAD).
GAS
T
ype
Mode
Super Heat
L
GAS T
ype
Mode
Super He
a
t
press
press
1
2
3
Fig. 2.m
12
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
1
2
Fig. 3.a
1
Red LED - see “Alarms”
2
Green LED - power supply ON
Model with display
GAS Type
Mode
Super Heat
1
3
2
12
4
Fig. 3.b
Key
1
Parameter label (for commissioning)
2
Keypad
3
Control ON/OFF digital input status LED
4
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.
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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.
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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
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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
7
Subcritical CO2 showcase/cold room
20 400 13 7 15 -50 0 50 20
8
Hot gas bypass by pressure
20 200 - - - - - - - 3 -
9
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.
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C
T
E
L
F
S
V
CP
M
EV
T
S1
S2
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)
CP
PID proport. gain 15 0 800 -
ti
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.
EV
0 ...10 Vdc
regulator
T
P
010
Vdc
A
0%
100%
S1
S2
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
C
T
E
L
F
S
V
CP
M
EV
T
S1
S2
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”.
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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.
E
V1 V2
M T
E
V1 V2
M T
S
F
L
CP
C
P
EV
A
B
S1
S2
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.
E
V1 V2
M T
S
F
LEV
CP
C
T
S1
S2
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).
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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
DI configuration
1=start/stop - 2=control backup
11 2 -
Smooth_line
A: superheat set point offset for
smooth lines
0 -99
(-55)
99
(55)
K/°F
t
Temp. set
SH set
SH_set+
Smooth_line
t
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.
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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.
t
t
t
OFF
ON
A
OFF
ON
Low_SH
Low_SH_TH
SH
D
B
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.
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t
t
t
OFF
ON
ALARM
OFF
ON
LOP
LOP_TH
T_EVAP
D
B
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.
t
t
t
t
OFF
ON
ALARM
OFF
ON
PID
OFF
ON
MOP
MOP_TH - 1
MOP_TH
T_EVAP
D
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
30
(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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