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µRack
Standard compressor racks single/two circuit
User manual
NO POWER
& SIGNAL
CABLES
TOGETHER
READ CAREFULLY IN THE TEXT!
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 ELECTRONIC 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.
WARNING: 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 CAREFUL LY IN THE TEXT!
CONTENTS
1 PRODUCT ...................................................................................................................................................................................................... 7
1.1 General functions ..............................................................................................................................................................................................7
1.2 Main characteristics ..........................................................................................................................................................................................7
2 USER INTERFACE .......................................................................................................................................................................................... 8
2.1 Buttons - LEDs - Icons ......................................................................................................................................................................................8
2.2 LED display and Icons ......................................................................................................................................................................................9
3 STARTING THE UNIT .................................................................................................................................................................................. 10
3.1 Starting for the first time ..................................................................................................................................................................................10
3.2 Unit configuration ............................................................................................................................................................................................10
3.3 Meaning of the inputs / outputs .......................................................................................................................................................................10
4 COMPRESSOR MANAGEMENT .................................................................................................................................................................. 13
4.1 General settings ..............................................................................................................................................................................................13
4.2 Compressor rotation .......................................................................................................................................................................................13
4.3 Compressor control .........................................................................................................................................................................................13
4.4 Number of compressors started with probe 1 fault .........................................................................................................................................14
4.5 Compressors with different capacities ............................................................................................................................................................15
4.6 Manually enable/disable the compressors ......................................................................................................................................................15
4.7 Special MT-LT units ........................................................................................................................................................................................16
4.8 Compressor time settings ...............................................................................................................................................................................16
5 FAN AND INVERTER MANAGEMENT ......................................................................................................................................................... 18
5.1 Fan management ............................................................................................................................................................................................18
5.2 Dead band control ...........................................................................................................................................................................................18
5.3 Inverter management ......................................................................................................................................................................................19
5.4 PWM-PPM management ................................................................................................................................................................................21
5.5 Floating condenser control ..............................................................................................................................................................................21
6 VARIOUS SETTINGS .................................................................................................................................................................................... 22
6.1 Manual device operation .................................................................................................................................................................................22
6.2 Compressor hour counter and maintenance alarm .........................................................................................................................................22
6.3 Set point variation from digital input ................................................................................................................................................................22
6.4 Type of refrigerant ...........................................................................................................................................................................................22
6.5 Auxiliary probe management ..........................................................................................................................................................................22
6.6 Prevent high discharge pressure ....................................................................................................................................................................23
7 ALARM MANAGEMENT .............................................................................................................................................................................. 24
7.1 Alarms with automatic reset ............................................................................................................................................................................24
7.2 Alarms with manual reset ................................................................................................................................................................................24
7.3 Semiautomatic alarms ....................................................................................................................................................................................24
7.4 Alarm relay ......................................................................................................................................................................................................24
7.5 Alarms from analogue inputs: temperature probe and pressure transducer: ..................................................................................................25
8 THE SUPERVISOR NETWORK ..................................................................................................................................................................... 26
8.1 Serial boards ...................................................................................................................................................................................................26
8.2 Communication protocols ...............................................................................................................................................................................26
9 USER INTERFACE ........................................................................................................................................................................................ 26
10 LIST OF PARAMETERS .............................................................................................................................................................................. 27
11 ON/OFF FAN CONTROL BOARD (CODE CONVONOFF0) .................................................................................................................... 32
12 PWM TO 0 TO 10 VDC (OR 4 TO 20 MA) CONVERSION BOARD FOR FANS (CODE CONV0/10A0) ................................................ 33
13 PROGRAMMING KEY (CODE PSOPZKEYA0) .......................................................................................................................................... 33
14 SUPERVISOR MANAGEMENT ................................................................................................................................................................... 33
15 DEFAULT CONFIGURATIONS .................................................................................................................................................................. 36
16 GLOSSARY ................................................................................................................................................................................................. 37
17 TECHNICAL SPECIFICATION .................................................................................................................................................................... 37
18 PRODUCT CODES LIST ............................................................................................................................................................................ 38
19 APPENDIX: COMPRESSOR RACK CONTROLLER, EXAMPLES OF APPLICATION DIAGRAMS ................................................ 39
20 APPENDIX: CHANGES INTRODUCED IN FW RELEASE 2.0 FOR MRK0000XX0 ........................................................................... 41
21 APPENDIX: CHANGES INTRODUCED IN FW RELEASE 2.1 ............................................................................................................. 42
22 APPENDICE: MODIFICHE INTRODOTTE NELLA RELEASE FW 2.2 ................................................................................................ 42
Cod.
C
1
1.1
1
2
3
4
5
6
7
8
9
1
1
1
1
1
1
1
1.2
Main
f
•
•
•
•
•
Devic
e
Comp
r
•
•
Progr
a
•
•
•
•
•
Hard
w
•
C
AREL +03P22
0
Product
General
f
1
. Read press
u
2
. Manageme
n
3
. Manageme
n
4
. Setting of th
5
. Rotation of
t
6
. Fan speed c
7
. Compresso
r
8
. Possibility t
o
parameter v
9
. Possibility t
o
1
0. Multifunctio
1
1. Set point va
r
1
2. Possibility t
o
1
3. Enable com
p
1
4. Proportiona
l
1
5. Floating con
1
6. Optional te
m
a-
O
b-
A
c-
C
d-
S
Main ch
a
f
unctions
Control of co
m
Control of con
Complete ma
n
Complete alar
m
Connection to
e
s controlled
r
essors (up to 4
h
Condenser fa
n
PWM speed c
o
a
mming
Display and c
o
Three levels o
f
Possibility to c
o
Possibility to c
o
Possibility to
m
w
are
The product c
o
0
431 rel. 2.2 date
f
unctions
u
re transducers, d
i
n
t of compressors
n
t of compressor
r
e number of co
m
t
he compressors
(
ontrol (PWM OU
T
r
and fan dead ba
o
enter the comp
v
alues.
o
enter the fan se
t
n input: general
H
r
iation from digit
a
o
set the compres
s
p
ressors from th
e
l
plus integral fun
n
denser set point
m
perature probes
O
utside ai
r
A
mbient air
C
ompressor disc
h
S
uction temperat
u
a
racteristic
s
m
pressor suction
p
densing pressure
n
agement of the
o
m
management;
serial line for su
p
h
ermetic compres
s
n
s (max 4)
o
ntrol
o
ntrol of the valu
e
f
parameter prote
c
o
nfigure all the u
n
o
nfigure the mai
n
m
odify the access
l
o
mes ready for p
a
d 10/02/12
i
splay data in BA
R
with the same a
n
r
acks with two cir
c
m
pressors – fans o
(
FIFO and by tim
e
T
PUT)
nd management
ressor set point i
t
point in BAR or
d
H
P alarm, ON/OF
F
a
l input
s
or-fan thermal o
v
e
“Maintenance” s
ction for the fan i
n
, with high temp
e
h
arge temperatur
e
u
re
s
p
ressure
(compressor dis
c
o
utputs available;
p
ervision / telema
i
s
ors, no part up t
o
e
s measured, on
L
c
tion: SEL (USER)
n
it parameters usi
n
unit parameters
l
evel to the para
m
a
nel installation, 3
R/
°C (depending
o
n
d different capac
c
uits, MT and LT
n the unit
e
). FIFO rotation
o
n BAR and displ
a
d
egrees centigrad
e
F
, change SET PO
I
v
erload/generic a
l
creen
n
verter.
e
rature alarm thre
s
e
c
harge)
i
ntenance;
o
2 hermetic-load
ED display
, PRG (INSTALLE
R
ng a hardware k
e
via serial line.
m
eters from the k
e
2x74, and DIN ra
i
7
o
n the type of ref
r
ities
o
f the fans.
a
y the value in °
C
e, depending on
t
INT,…
larm as automati
c
s
hold:
d
capacity-controll
e
R
), SEL+PRG (MA
N
e
y.
e
ypad (only from
i
l mounting.
r
igerant gas)
C
by pressing the
t
he control probe
c
/manual
e
d compressors)
N
UFACTURER)
MANUFACTURE
R
“UP” and “DO
W
used (pressure
o
R
level).
W
N” buttons toge
t
o
r NTC).
t
her when displa
y
µRack
y
ing the
Cod.
C
2
The p
r
As we
l
param
2.1
+
+
C
AREL +03P22
0
User inter
f
r
oduct uses a 3 di
l
l as displaying t
h
eters. The followi
Buttons
-
Button
a
b
c
(
d
(
a
b
c
d
a
b
c
a
E
U
-
-
U
-
-
b
c
d
e
+
P
+
P
t
0
431 rel. 2.2 date
f
ace
git LED display w
h
e values measur
e
ng figures show t
h
-
LEDs - Ic
o
a
) Press the butto
b
) Press the butto
c
) Press the butt
o
(
control pressure
/
d
) Press the butto
(
control pressure
/
a
) Press the butto
b
) Press the butto
c
) Press the butto
n
d
) Press the butto
a
) Press the butto
b
) Press the butto
c
) Press the butto
n
a
) Press the butto
E
xample:
U
nit “A” single cir
c
-
standard LP1
-
the arrows scroll
t
U
nit “B” two circu
-
standard LP1
-
the arrows scroll
t
b
) Press the butto
c
) Press the butto
n
d
) Press the butto
e
) Press the butto
P
ress the two but
t
P
ress the two but
t
1. comp
/
2. high/l
o
t
o switch the disp
l
d 10/02/12
ith minus sign an
d
e
d and the oper
a
h
e µRack for pan
e
o
ns
n, when switchin
g
n for more than
5
o
n for more than
/
temperature)
n for more than
3
/
temperature)
n for more than
5
n when the list o
f
n
when the num
e
n when a digital
v
n for more than
5
n when the list o
f
n
when the num
e
n to display the o
t
c
uit
t
o HP-B2 –B3
it
t
o LP2-HP-B3
n for more than
5
n
when the list of
n when the num
e
n when a digital
v
t
ons together for
5
t
ons together, wh
e
/
fan set point
o
w threshold
l
ay of the same p
a
d
decimal point t
o
a
ting conditions o
e
l installation and
g
the instrument
o
5
sec, to set the p
a
3 sec, when th
e
3
sec when the li
s
5
sec to select bet
w
f
parameters is di
s
e
ric value of a par
a
v
alue is displayed
5
sec to set the pa
f
parameters is di
s
e
ric value of a par
a
t
her controlled v
a
5
sec to select the
parameters is di
s
e
ric value of a par
v
alue is displayed
5
seconds to set t
h
e
n the numeric v
a
a
rameter from B
A
8
o
display the mo
n
o
f the unit, the u
s
for DIN rail mou
n
Fig. 2.a
D
e
o
n, until the strin
g
a
ssword for acce
s
e
list of paramet
e
s
t of parameter g
r
w
een the display
s
played to move
t
a
meter is display
e
(YES-NO) to cha
n
ssword for acces
s
s
played to show t
h
a
meter is display
e
a
lues. The “label”
probe displayed
s
played to move t
o
r
ameter is display
e
(YES-NO) to cha
n
he PWD for acce
s
a
lue of one of th
e
A
R to °C.
n
itored values, an
d
s
er terminal (disp
l
n
ting.
e
scription
g
“DEF” is shown
o
sing the INSTALL
E
e
rs is displayed, t
o
r
oups is displayed
of the values in “
B
t
o the next param
e
d to increase the
n
ge the setting.
s
ing the USER par
a
h
e numeric value
e
d to accept the n
of the probe will
b
permanently as t
h
o
the previous pa
e
d to decrease th
e
n
ge the setting
s
sing the MANUF
A
e
following param
e
d
ICONS for the s
l
ay and keypad)
c
o
n the display, to
E
R parameters.
o
accept the mo
d
,
“-/-”, “-C-”, “-r-”,
B
AR” or “°C”.
e
ter.
value.
a
meters.
of the parameter
umeric value and
b
e displayed, and
h
e main probe.
ramete
r
e
value.
A
CTURER parame
t
e
ters is displayed:
s
tatus of the devi
c
c
an be used to
m
load the default
v
d
ifications and re
,
“-A-”, “-M-”, to r
e
r
.
d
return to the list
d
then the numeri
ters and thus con
:
c
es and operating
m
odify the unit o
p
v
alues.
t
urn to the main
e
turn to the main
of parameters.
c
value.
figuring the contr
T
µRack
modes.
p
erating
display
display
oller.
T
ab. 2.a
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
9
2.2 LED display and Icons
The display shows the control value, temperature or pressure. depending on the selection made from the keypad.
In the event of alarms, the display shows the monitored and the alarm information in sequence.
ICONS
Description
On when the unit of measure selected is BAR
On when the unit of measure selected is °C
On when there is an ACTIVE ALARM
1) On when the MANUFACTURER parameters are being configured
2) If flashing with the ALARM icon indicates the compressor maintenance hours have been exceeded.
1) On when the value read by the suction probe is displayed
2) If flashing with the ALARM icon indicates the activation of suction probe alarms:
High Temp.
Low Temp.
Probe not connected
1) On when the value read by the discharge probe is displayed
2) If flashing with the ALARM icon indicates the activation of discharge probe alarms:
High Temp.
Probe not connected
1) On when the fan parameters are being configured.
2) On when at least one fan is operating
3) If flashing with the ALARM icon indicates the activation of fan alarms
1) On when the compressor parameters are being configured.
2) On if at least one compressor step is active
3) If flashing with the ALARM icon indicates the activation of the compressor alarms
1
2
3
4
1) Indicates the state of the compressors and capacity control on
2) If flashing indicates the ON/OFF call for a new compressor step, while the device is awaiting the expiry of the delay times.
3) If the controller is used for fan control only (“/01”=0) then the icon shows the status of the fans.
Tab. 2.b
Cod.
C
3
3.1
After
h
W
hen
Unit
w
3.2
The u
n
/
09. T
h
First t
h
Relay
n
•
•
The s
e
If 4 d
e
contr
o
contr
o
3.2.1
Inputs
only).
exists
w
If 4 de
Param
•
•
•
•
•
•
•
•
•
•
•
•
•
3.2.2
The c
o
The u
n
1
2
3
4
Shutti
n
•
•
3.3
3.3.1
T
Analo
g
Input
B1
B2
B3
B4
C
AREL +03P22
0
Starting t
h
Starting
f
h
aving checked th
e
started for the fir
s
w
ith 2 compressor
s
Unit con
f
n
it can be set as s
h
e maximum nu
m
h
e compressors +
n
o. 5 may be:
•
an alarm
•
a fan
e
lection is made a
e
vices are select
e
lled (e.g.: 2 com
p
l or inverter, can
b
Input confi
g
from 1 to 4 are
a
The user can de
c
w
hen the contact
vices , or less, ar
e
eter /15 can be u
•
0: no functi
o
•
1: unit ON-
O
•
2: change s
e
•
3: general h
•
4: general h
•
5: general l
o
•
6: general l
o
•
7: general l
o
•
8: general l
o
•
9: liquid lev
e
•
10: liquid le
v
•
11: fan ther
m
•
12: fan ther
m
Unit ON/O
F
o
ntroller is norma
l
n
it can be switche
1
. Alarm (para
m
2
. Supervisor
(
3
. Digital inpu
t
4
. Parameter (
p
n
g down the unit,
•
switches th
e
•
stops the m
Meaning
Table of an
T
he tables below
d
g
ue inputs
Descriptio
Ratiometri
c
Room tem
Outside ai
r
Ratiometri
c
0
431 rel. 2.2 date
h
e unit
f
or the fir
s
e
connections, p
o
s
t time, the contr
o
s
+ 2 fans + alar
m
f
iguration
ingle or two circu
m
ber of devices, c
o
capacity contr
o
utomatically acco
e
d (e.g.: 2 compr
p
ressors (not ca
p
b
e set for the fan
s
g
uration
a
larm inputs for t
h
c
ide whether the
is closed) by sett
i
e
connected to th
e
sed to configure
t
o
n
O
FF (ON contact
N
e
t point (set1- set
2
igh pressure swit
c
igh pressure swit
c
o
w pressure switc
h
o
w pressure switc
h
o
w pressure switc
h
o
w pressure switc
h
e
l alarm NC
v
el alarm NO
m
al overload/gen
m
al overload/gen
F
F
l
ly configured as
a
e
d on and off by:
m
eter A22 can b
e
(
parameter /38 c
a
t
(parameter /15
c
p
arameter /39 ca
as shown on the
e
controller off;
anagement of th
e
of the inp
u
alogue inputs
d
escribe the type
n
c
discharge press
u
perature probe (
d
r
temperature pr
o
c
suction pressur
e
d 10/02/12
s
t time
o
wer-up the unit.
o
ller performs a L
A
m
relay.
it, the number of
o
mpressors + fan
o
l and then the fa
rding to the num
b
essors (not cap
a
p
acity-controlle
d
s
, managed using
h
e compressors a
n
alarm inputs are
i
ng parameter /1
4
e
controller, input
t
he multifunction
N
C)
2
)
c
h NC
c
h 1 NO
h
circuit 1 NC
h
circuit 1 NO
h
circuit 2 NC
h
circuit 2NA
eric NC
eric NO
a
lways ON.
e
used to select
w
a
n be used to ena
c
an be used to c
o
n be used to swit
c
display by the m
e
e
various devices
a
u
ts / outpu
of the probes th
a
u
re probe
d
isplay) / auxiliar
y
o
be (floating cond
e
probe / probe i
n
A
MP TEST and us
compressors for
o
s, is 5 (maximum
ns will be allocat
e
b
er of devices (fa
n
a
city-controlled
)
d
) + 3 fans), outp
the PWM signal.
n
d fans configure
d
normally closed
(
4
.
5 automatically
b
input:
w
hether or not a b
r
b
le unit shutdow
n
o
nfigure the multi
f
c
h the unit on or
e
ssage “OFF”:
a
nd the related al
ts
a
t can be connect
e
y
probe
enser control) / a
n
2nd circuit
10
s
es the default val
o
ne or two circui
t
number of relay
s
e
d, in sequence.
n
s and compress
o
)
+ 2 fans) rela
y
ut no. 5 is autom
d
. If 5 devices are
(
the alarm condit
b
ecomes a multif
u
roken probe alar
m
n
from the super
v
f
unction input as
O
off)
arms.
e
d to the inputs a
uxiliary probe
u
es selected by
C
s using paramete
s
).
o
rs) selected.
y
5 can be used
atically used to c
o
controlled by th
e
ion exists when t
h
u
nction input.
m
should switch t
h
v
isor).
O
N/OFF).
nd their characte
r
Type of pr
o
RATIOMET
R
CAREL NTC
CAREL NTC
RATIOMET
R
A
REL for all the c
o
r
/01; the numbe
r
as an alarm rela
y
o
ntrol a fan. In a
d
e
unit, input no. 5
h
e contact is ope
n
h
e unit off).
r
istics.
o
bes that can be
R
IC pressure prob
e
temperature pro
b
temperature pro
b
R
IC pressure prob
e
o
nfiguration para
m
r of fans can then
a
y (default settin
g
d
dition, the use o
f
is automatically
a
n) or normally o
p
connected
e
(0 to 5 Volt) or
b
e (-50T100°C; R
/
b
e (-50T100°C; R
/
e
(0 to 5 Volt)
m
eters:
be set using par
a
g
), while if 5 dev
f
speed control, b
y
a
n alarm input (fa
p
en (the alarm c
o
NTC if /16
/
T 10 k at 25°C)
/
T 10 k at 25°C)
T
µRack
a
meter
ices are
y
phase
n alarm
o
ndition
T
ab. 3.a
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
11
Digital inputs
Input Description Type of device connected
ID1
Compressor 1 / fan alarm Generic compressor/fan alarm. Voltage-free contact.
ID2 Compressor 2 /
capacity-control
/ fan alarm
Generic compressor /
Power contactor for capacity control activation
/fan alarm.
Voltage-free contact.
ID3 Compressor 3 /
capacity-control /
fan alarm
Generic compressor /
Power contactor for capacity control activation
/fan alarm.
Voltage-free contact.
ID4 Compressor 4 /
capacity-control
/ fan alarm
Generic compressor /
Power contactor for capacity control activation
/fan alarm.
Voltage-free contact.
ID5 Fan alarm / Multifunction input Generic alarm:
- compressor/fan.
- from general high/low pressure switch.
- fan thermal overload.
- liquid level.
Unit On-Off. Voltage-free contact.
Tab. 3.b
Digital outputs
Input Description Type of device connected
No1-C1 Compressor 1 / fan Power contactor for starting the compressor / fan
No2-C2 Compressor 2 / fan Power contactor for starting the compressor / fan
No3-C3 Compressor 3 / fan Power contactor for starting the compressor / fan
No4-C4 Compressor 4 / fan Power contactor for starting the compressor / fan
No5-C5 Alarm / fan Power contactor for starting the fan / voltage-free contact for signalling unit alarm
Tab. 3.c
Analogue outputs
Outputs Description
Y1
Fans speed controller (PWM)
Tab. 3.d
3.3.2 Wiring diagrams:
Panel installation:
Fig. 3.a
ext. temp. probe
amb. temp. probe
alarm 4
alarm 2
alarm 1
alarm 3
multifunctionD.I./alarm
Line
L
N
P
Line
LN
P
24 V
TRADR1W04
PSOPZKEY*
MCH2004850
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
12
DIN rail installation:
Fig. 3.b
Rack
Line
L
N
Rack
ext. temp. probe
amb. temp. probe
alarm 4
alarm 2
alarm 1
alarm 3
multifunctionD.I./alarm
P
Line
LN
P
FCSER00000
FCSER00000
TRADR1W04
24 V
Cod.
C
4
Inputs
• Suc
t
• Dig
• Mu
l
Outpu
• Co
m
4.1
Param
•
n
•
c
• t
y
The c
o
In the
4.2
Rotati
o
Rotati
o
If the
c
numb
e
In the
Three
LIFO
r
The fi
r
• S
t
• S
t
FIFO
r
The fi
r
• S
t
• S
t
This s
e
Rotati
o
The c
o
numb
e
4.3
In the
Propo
Propo
r
the di
f
Figure
Settin
g
SP + 1
SP +
2
…
SP +
D
ON
OFF
F
i
Dead
This t
y
meas
u
time
e
stopp
e
stop r
e
C
AREL +03P22
0
Compress
used:
t
ion pressure pro
b
i
tal inputs dedica
t
l
tifunction input f
o
ts used:
m
pressor output
s
General
s
eters used for O
N
n
umber of compr
e
c
ompressor times
y
pe of control
o
mpressors are m
case of two circui
Compres
o
n (parameter r0
5
o
n automatically
e
c
ompressor is of
f
e
r of compresso
r
default configura
t
different types of
r
otation (no rota
r
st compressor to
t
art: C1,C2,C3,C4.
t
op:C4,C3,C2,C1.
r
otation
r
st compressor to
t
art: C1,C2,C3,C4
t
op: C1,C2,C3,C4.
e
lection enables t
h
o
n by time
o
mpressor that st
a
e
r of operating h
o
Compres
default configura
t
rtional band
r
tional band cont
r
f
ferential band. P
a
4.1 shows the ac
t
g
the parameters
l
*DF/ (No. of ste
p
2
*DF/ (No. of ste
p
D
F for th
1° compr.
co
m
i
g 4.a
band
y
pe of control fea
t
u
red value excee
d
e
lapsed outside o
e
d when the mea
s
e
quests. In this ca
s
0
431 rel. 2.2 date
or manag
e
be/probes
t
ed to the compr
e
o
r generic alarm
(
s
and capacity c
s
ettings
N
/OFF control:
e
ssors (capacity
-
anaged by the co
ts, the set point a
sor rotatio
5
) of the compre
s
e
xcludes any com
p
f
for alarm or dis
a
r
s available.
t
ion, FIFO rotatio
n
rotation can be s
e
tion)
start will be the l
a
start will be the fi
h
e rotation of the
a
rts will be the on
o
urs will stop.
sor contro
l
t
ion, “dead band
”
r
ol calculates, bas
e
a
rameters r01 (se
t
t
ivation points fo
r
l
isted above, eac
h
p
s) for the first;
p
s) for the secon
d
e last.
m
pr./capac. contr.
DF
t
ures the definiti
o
d
s the limit to the
f the dead band.
s
ured value falls
b
s
e too, the first d
e
d 10/02/12
e
ment
e
ssor safety devic
e
(
general suction
p
ontrol
-
controlled and
ntroller based on
nd the differentia
n
s
sor calls ensures
p
ressors with alar
a
bled, is exclude
n
has been select
e
e
t: for the capac
i
a
st to stop, first c
a
rst to stop.
compressors so
a
e with the lowest
l
”
control is activat
e
e
d on
v
arious pa
r
t
point) r02 (diffe
r
r
a system with 4
s
h
individual step
w
d
;
c
o
compr./
capac. c
o
o
n of a dead ban
d
right (measured
The first device
b
elow the dead b
a
e
vice stops imme
d
e
s
ressure switch 1
a
not)
a pressure set p
o
l
also need to be
t
hat the number
o
m or that are dis
a
d
from regulatio
n
e
d.
ty control, only
d
a
pacity control a
a
s to even out as
m
number of opera
e
d (parameter r0
6
ameters (SP, DF
a
r
ential).
s
teps.
w
ill have a differe
n
o
mpr./
capac.
t
o
ntr.
RP
d
to the side of t
h
value greater tha
will start immedi
a
nd (measured v
a
d
iately, while the
o
13
a
nd 2)
o
int (parameter r
0
set for the secon
d
o
f operating hou
r
a
bled.
n
and rotation; th
e
devices rotation t
y
ctivated will be
t
much as possible
a
ting hours. Whe
n
6
).
a
nd the number
o
n
tial as follows:
h
e set point, withi
a
n SP + DZN, se
e
ately, while the
o
a
lue less than the
o
thers wait the d
e
Key:
SP
DF
RP
0
1) and differenti
a
d
circuit (paramet
e
r
s and the numbe
e
activation/dea
c
y
pe available is LI
t
he last deactiva
t
the number of c
o
stopping the exa
o
f devices set) th
e
n
which no devic
e
Figure 4.3). Th
e
o
thers will wait t
h
set point), and r
e
e
lay time betwee
n
Compressor se
t
Compressor dif
f
Pressure read
a
l (parameter r02
)
e
rs r03 and r04).
r
of starts of the
d
c
tivation threshol
d
F
O (no dependi
n
t
ed:
o
mpressor operat
c
t opposite is tru
e
e
points where th
e
e
is started or sto
number of devi
c
h
e set time betw
e
e
mains there for
a
n
stops (r09).
point (r01)
f
erential (r02)
)
, measured by th
d
ifferent compres
s
d
s are re-calcula
t
n
g by r05) para
m
t
ing hours.
e
, that is, the com
e
devices must s
w
o
pped. The devic
e
c
es to be activate
d
e
en starts (r07).
S
a
period equal to
e suction probe.
s
ors balance out.
t
ed based from
a
m
eter:
pressor with the
h
w
itch on and off, i
n
e
s are activated w
d
varies accordin
g
S
imilarly, the dev
the time betwee
n
µRack
a
ctual
h
ighest
n
side
hen the
g
to the
ices are
n
device
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
14
Also see the paragraph on Time settings.
The program will switch the devices on according to the start-up logic configured and the availability of the devices
DOffZ
DOnZ
NZ
SP
DZN
RP
Fig. 4.b
Compressor dead band with variable times
The user can decide to set a variable time between calls, depending on whether the pressure is moving away from the dead band. In particular, the activation /
deactivation time of the outputs decreases as the distance from the dead band increases. To set this function, the following parameters must be configured:
• Maximum compressor on time/ capacity control (parameter r08)
• Minimum compressor on time/ capacity control (parameter r07)
• Pressure differential within which the time varies. (parameter r11)
• Maximum compressor off time/ capacity control (parameter r10)
• Minimum compressor off time/ capacity control (parameter r09)
Fig. 4.c
Key:
InPress
Suction pressure DTNZ Differential within which the time varies
STPM Control set point TOnMax Maximum compressor on time
RBM Control band TOnMin Minimum compressor on time
NZ Dead band TOffMax Maximum compressor off time
DOnZ Device activation zone TOffMin Minimum compressor off time
DOffZ Device deactivation zone
In the activation phase, the following cases are possible:
1. Pressure equal to point b
same call time as the “maximum compressor on time”
2. Pressure between point b and point b + DTNZ
type of call between “Max on time” and “Min on time”
3. Pressure greater than or equal to point b + DTNZ
same call time as “Min on time”
In the deactivation phase, on the other hand, the following cases are possible:
1. Pressure equal to point STPM
same call time as the “maximum compressor off time”
2. Pressure between point STPM and point STPM - DTNZ
type of call between “Max off time” and “Min off time”
3. Pressure greater than or equal to point STPM - DTNZ
same call time as “Min off time”
N.B. To make the device call time constant in the activation phase, simply set the times TOnMax and TonMin to the same value. The same is true for the deactivation
phase.
4.4 Number of compressors started with probe 1 fault
In the event of a suction probe fault or not connected alarm, parameter /07 indicates the number of outputs (compressors and capacity control, configured with
capacity-controlled compressors), forced on, so as to ensure minimum cooling/operation of the installation.
For two circuits, the parameter relating to the second circuit /08 must also be set. This will be related to the probe in the 2nd circuit.
Key:
DOffZ
Device deactivation zone
DOnZ Device activation zone
NZ Dead band
DZN Dead band differential
RP Suction pressure read
SP Set point
STPM
RBM
NZ DOffZ DOnZ
InPress [ºbar]
TOnMin TOffMin
TOnMax TOffMax
DTNZ
B
DTNZ
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
15
4.5 Compressors with different capacities
Parameter /02 is used to choose the option of compressors with different capacities.
This allows more load steps and therefore finer control.
Once the capacity of the individual compressors has been defined (parameters /03, /04, /05, /06), the software, based on the requirements of the installation and the
compressors available (without alarms or timers), will calculate the most suitable combination to satisfy the requirement. Whenever the requirement changes, the
software recalculates the most suitable combination. The combination will always be greater than or equal to the requirement.
If two compressors have the same capacity, the compressor with the lower index will always be the first to start.
4.5.1 Proportional band control with different capacity compressors
Based on the pressure, the set point and the differential, the software will proportionally calculate the capacity required to bring the pressure back near the set point.
At the set point plus differential the requirement will be at the maximum value, while it will be null for pressure values around or less than the set point.
alDifferenti
pressSetpointCapacityMax
requiredCapacity
)(_
_
−×
=
4.5.2 Dead band control with different capacity compressors
The software will calculate the maximum number of combinations possible with the compressors available.
At certain intervals of time (see the paragraph on Compressor dead band with variable times), the software will call a sequence with a higher capacity.
In the deactivation phase, the opposite will occur, while in the dead band no compressors will be started or stopped.
An increase in the requirement will correspond to a different combination.
Fig 4.d
4.5.3 Example of compressors with different capacities
The following example looks at an installation featuring 3 compressors with different capacities, using proportional band control. As can be seen, there are 8 possible
combinations available.
Set point 1.0 bar
“r01”
Differential 2.0 bar “r02”
Comp1 5 kW “/03”
Comp2 7 kW “/04”
Comp3 15 kW “/05”
Maximum capacity 27 kW “/06”
Pressure Requirement kW Comp1 Comp2 Comp3 Total active capacity kW
1.1
1.35 X
5
1.6 8.1 X X 12
1.8 10.8 X X 12
2 13.5 X 15
2.1 14.85
X 15
2.4 18.9 X
X 20
2.5 20.25
X X 22
3 27 X X X 27
Tab 4.a
4.6 Manually enable/disable the compressors
A compressor can be temporarily disabled from the control sequence. This function is very useful when needing to perform maintenance on an individual compressor.
The corresponding alarms are still managed.
The following parameters are used: M01,M02,M03,M04 to enable the manual operation of the compressors. The real manual function is managed using parameters:
M05,M06,M07,M08.
On unit models with capacity control (/01=9,10,...14) the compressors cannot be manually enabled/disabled directly. To exploit parameters M01,..,M08,
the unit model needs to be changed (/01=1 for configurations 9, 10 and 11; /01=3 for configurations 12 and 13; /01=4 for configuration 14).
DOffZ
DOnZ
NZ
SP
DZN
RP
Key:
DOffZ
Device deactivation zone
DOnZ Device activation zone
NZ Dead band
DZN Dead band differential
RP Suction pressure read
SP Set point: compressors (S2); fans (S1)
Cod.
C
4.7
4.7.1
The h
a
mediu
speed
Below
This t
y
1
2
4.7.2
Low p
r
Low p
r
High
p
Temp
e
Temp
e
4.8
The fo
Time
b
Param
This a
p
Mini
m
Sets t
h
R
C
m
C
AREL +03P22
0
Special
M
Manageme
n
a
rdware features
o
m installations, h
a
managed by the
is an example di
a
y
pe of system can
1
. the compre
s
2
. the max nu
m
allocated to
Probes and
Functio
n
r
essure circuit 1
r
essure circuit 2
p
ressure circuit di
s
e
rature 1
e
rature 2
Compres
llowing is a list of
b
etween stop re
q
eter C06 sets a st
p
plies both in the
m
um compressor
h
e minimum time
m
p
0
431 rel. 2.2 date
M
T-LT unit
s
nt of compresso
o
f the µRack cont
r
a
ving the advanta
speed controller
o
a
gram:
be controlled by
s
sors must have t
h
m
ber of compres
s
probe LP1, and t
h
values controll
e
n
s
charge
sor time s
e
all the time para
m
q
uests with HP
p
t
op delay betwee
n
dead band and i
n
ON time
the compressors
Fig 4.f
TMinOn
Fl
o
d 10/02/12
s
r racks with LT a
r
oller can be ada
p
ge of being com
p
o
r external press
u
µRack in the foll
o
h
e SAME CAPACI
T
s
ors in the MT un
i
h
e other compre
s
e
d
B4 (pressure)
B1 (pressure)
B1 (pressure)
B2 (temperatu
r
B2 (temperatu
r
B3 (temperatu
r
e
ttings
m
eters used for c
o
p
revent active
n
one compresso
r
n
the proportiona
stay on, that is,
o
o
ating condenser SET
Condense
r
Liquid r
e
nd MT circuits a
p
ted for the contr
o
p
act and offering l
re switches, and
s
o
wing conditions:
T
Y
i
t and LT unit is 4.
sor rack to probe
Input
r
e)
r
e)
r
e)
o
mpressor mana
g
r
and the next, if t
h
l band.
nce activated, m
u
T[s]
T[s]
Do
u
co
m
e
ceive
r
16
nd condenser o
n
o
l of a special typ
e
l
ow cost solution
s
s
eparate manage
m
Fig 4.
e
.
There can there
f
LP2.
C
LP1
LP2
HP
B2
B3
g
ement (and not
he high pressure
u
st remain on for
t
K
e
R
C
m
T
M
T
u
ble circuit
m
pressor uni
t
µR
a
n
ly.
e
of compressor
r
s
. These are com
p
m
ent of the com
p
e
f
ore be combinati
o
o
de on display
capacity contr
o
prevention (prev
e
t
he time set by th
e
y:
Com
p
m
p Com
p
M
inOn Mini
m
Time
ac
ack that is becom
ressor racks with
p
ressors in the M
T
o
ns of 2+2, 3+1,
Type of u
n
A- Single cir
c
B- Compres
s
A -B
B
A (press –
t
B (only te
m
A
(AUX pr
o
B (not use
d
A
lways pre
s
o
l).
e
nt) function is a
c
is parameter (pa
r
ressor call
resso
r
m
um ON time
m
ing more widely
only the conden
s
T
and LT units.
1+1. One compr
e
n
it:
c
uit compressor rac
s
or racks with 2 circ
temp)
m
p)
o
be)
d
)
e
sent
c
tive.
r
ameter C01).
MT display cabinet
group
LT display cabine
t
u
sed in small an
d
s
ing section, and
w
e
ssor rack will be
k
uits M
T
-BT
T
µRack
d
w
ith fan
T
ab 4.b
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
17
Minimum compressor OFF time
Sets the minimum time the compressors stay off. The devices are not started again if the minimum time selected (parameter C02) has not elapsed since the last stop.
Fig. 4.g
Minimum time between starts of different compressors (proportional band)
This represents the minimum time that must elapse between the start of one device and the next. This parameter allows simultaneous starts to be avoided (parameter
C03).
Fig 4.h
With capacity control compressors is established fixed delay = 5 s, between a capacity control and the following.
Minimum time between starts of the same compressor
Sets the minimum time that must elapse between two starts of the same compressor.
This parameter limits the number of starts per hour. If, for example, the maximum allowable number of starts per hour is 10, to guarantee this limit simply set a value of
360 (parameter C05).
Key:
R
Compressor call
Cmp
Compressor
TSameSw
Minimum time between starts of the same compressor
T
Time
Fig 4.i
Key:
R
Compressor call
Cmp Compressor
TMinOff Minimum OFF time
T Time
Key:
R
Compressor calls
Cmp1 Compressor 1
Cmp2 Compressor 2
TDiffSw Minimum time between starts of different compressor
T Time
T[s]
R
T[s]
Cmp
TMinOff
T[s]
R
T[s]
Cmp1
T[s]
Cmp2
TDiffSw
T[s]
R
T[s]
Cmp
TSameSw
Cod.
C
5
Inputs
• Dis
c
• Dig
• Mu
l
Outpu
• Co
n
• Co
n
5.1
The o
p
One t
h
“prop
o
5.1.1
Propo
Propo
r
the di
f
Figure
Settin
g
SP + 1
SP +
2
…
SP +
D
ON
OFF
5.2
This t
y
The d
e
activat
Simila
r
the ti
m
The p
r
Fan r
o
The r
o
Rotati
o
If the
f
fans
a
Two d
C
AREL +03P22
0
Fan and i
n
used:
c
harge pressure/t
e
i
tal inputs for the
l
tifunction input f
o
ts used:
n
denser fan outp
u
n
denser fan spee
d
Fan man
a
p
eration of the fa
n
h
ermal overload i
s
o
rtional band” co
n
Fan control
rtional band
r
tional band cont
r
f
ferential band.
5.1 shows the ac
t
g
the parameters
l
*DF/ (No. of ste
p
2
*DF/ (No. of ste
p
D
F for th
Dead ba
n
y
pe of control feat
e
vices are activat
e
e
d varies accordi
n
r
ly, the devices ar
m
e between devic
e
r
ogram will switc
h
o
tation
o
tation of the fan
s
o
n automatically
f
an is off for alar
m
vailable.
ifferent types of
r
0
431 rel. 2.2 date
n
verter ma
e
mperature prob
e
fan safety device
s
o
r generic alarm
(
u
ts
d
control (PWM o
u
a
gement
n
s depends on th
e
s
featured for eac
h
n
trol is set (para
m
r
ol calculates, ba
s
t
ivation points fo
r
l
isted above, eac
h
p
s) for the first;
p
s) for the secon
d
e last.
Fig. 5.
a
n
d control
ures the definitio
n
e
d when the mea
s
n
g to the time ela
p
e stopped when
t
e
stop requests. I
n
h
the devices on a
s
, settable by pa
r
excludes any fa
n
m
or disabled, is
r
otation can be s
F
d 10/02/12
nagement
e
s
(
general discharg
e
u
tput)
e
value read by t
h
h
fan step. This h
a
m
eter r21), and FI
F
s
ed on various pa
r
a system with 4
s
h
individual step
w
d
;
DF
a
n
of a dead band
s
ured value exce
e
p
sed outside of t
h
t
he measured val
u
n
this case too, th
ccording to the s
t
r
ameter r20, is a
i
n
s with active al
a
excluded from r
e
et:
ig. 5.b
e
pressure switch
)
h
e discharge pres
s
a
s a settable imm
F
O rotation (para
m
rameters (SP, DF
s
teps.
w
ill have a differe
n
R
to the side of the
e
ds the limit to th
e
h
e dead band. Th
e
u
e falls below th
e
e
first device stop
art-up logic confi
g
med at balancin
g
a
rms.
e
gulation and rot
a
18
)
s
ure (or temperat
ediate reset and
w
m
eter r20).
and the numbe
r
n
tial as follows:
R
P
e
set point, within
e
right (measure
d
e
first device will
s
e
dead band (me
a
p
s immediately, w
h
g
ured and the av
a
g
the number of
o
a
tion; the activati
Key:
SP
DF
RP
ure) sensor.
w
ill only be valid
f
r
of devices set) t
h
which no device
i
d
value greater th
a
s
tart immediately
,
a
sured value less
t
h
ile the others w
a
a
ilability of the de
v
o
perating hours
a
on/deactivation t
Fan set point
Fan differential
Pressure read
Key:
DOffZ
NZ
DOnZ
DZN
RP
SP
f
or the specific fa
n
h
e points where
t
s started or stop
p
a
n SP + DZN, see
while the others
t
han the set poin
t
a
it the delay time
b
v
ices
a
nd starts of the
d
h
resholds are re
-
Device deac
t
Dead band
Device activ
a
Dead band
d
Discharge p
r
Fan set poin
t
n
. In the default c
o
t
he devices must
p
ed.
e
Figure 5.2). The
will wait the set t
i
t
), and remains t
h
between stops.
different fans.
-calculated base
t
ivation zone
a
tion zone
d
ifferential
r
essure read
t
o
nfiguration,
switch on and of
f
number of devic
e
i
me between star
t
h
ere for a period
e
d
from actual nu
m
µRack
f
, inside
e
s to be
t
s.
e
qual to
m
ber of
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
19
LIFO rotation (no rotation parameter r20=0)
The first fan that to start will be the last to stop.
• Start: Fan1, Fan2, Fan3, Fan4.
• Stop: Fan3, Fan3, Fan2, Fan1.
FIFO rotation (parameter r20=1)
The first fan that to start will be the first to stop.
• Start: Fan1, Fan2, Fan3, Fan4.
• Stop: Fan1, Fan2, Fan3, Fan4.
The rotation of the fans is implemented when called.
Various fan parameters
In the event of a discharge probe fault or not connected alarm, parameter /12 sets the number of fans that are forced on.
5.3 Inverter management
The fan controller is enabled by parameter /10.
A minimum limit value can be set for the inverter (parameter r29), as a percentage.
To assist the start of the inverter, a time can be set, expressed in seconds, during which the inverter is forced on at 100% at startup before proceeding with the normal
regulation. This parameter is called “Speed Up Time” (parameter r27).
Management of the fans slaved to the compressors
Parameter “/13” defines whether the fans can be activated independently or whether at least one compressor must be on. This is used to prevent the condenser fans
operating with high outside temperatures work when no compressor is operating. Typical application: cold rooms cold stores.
Parameter “/13” default = 0 (independent control).
Inverter control
Proportional band
This control requires the inverter set point STPI to be set (parameter r18 ), plus an inverter differential RBI (parameter r19).
If the value measured by the discharge probe is less than or equal to the value of the inverter set point, the inverter output will be 0.
Between the inverter set point STPI and point C (set point + differential), the value of the inverter output will be proportional to the value read by the discharge probe,
and in any case not less than the minimum inverter output MinIn. If the value measured by the discharge probe is greater than or equal to the inverter set point +
differential, the output will be at the maximum value. The control is not associated with any fan and can work without fans being configured.
Proportional control, set by parameter r21, may be proportional only (parameter r21=0) or proportional + integral (parameter r21=1).
Key:
STPI Fan inverter set point
RBI Inverter differential
Min In Minimum inverter opening
C Fan set point + differential
Key:
RB Fan differential
RBI Inverter differential
STPM Discharge set point
STPI Inverter set point
C Inverter set point + inverter differential
B Discharge set point + Fan differential
Min In Minimum value of the inverter control output
Fig.5.d
Fig. 5.c
µRack
Cod. CAREL +03P220431 rel. 2.2 dated 10/02/12
20
Proportional and integral control (PI)
To minimise any deviations in stable operating conditions between the controlled value and the set point, typical of proportional control, a proportional plus integral
strategy (P+I) can be sued.
This strategy helps overcome situations of stalemate in which the working point remains steadily at a value other than the set point.
PI control adds the integral action to proportional control. This action, when a control error persists, has an increasing effect over time on the overall control action.
The parameter that defines the integral action is the integral time (r22).
The default value is 600 s (10 min). The integral time corresponds to the time taken by the integral action, with a constant error, to balance the proportional action.
The lower the integral time, the faster the response of the control.
For further information, refer to classic control theory.
N.B.: Make sure the integral time is not set too low, otherwise control may become unstable.
The following figure highlights the difference between the proportional control and proportional plus integral control (with inverter):
Proportional control Proportional + Integral control
T[s]
SP
RP
T[s]
10 Volt
Min In
T[s]
RP
SP
T[s]
10 Volt
Min In
Fig. 5.e
Key:
RP
Pressure read
SP Set point
T Time
Min In Minimum inverter output value
Dead band control
This control requires the setting of inverter set point, the inverter pressure differential for “dead band” control (parameter r21) and the “inverter ramp up time”
(parameter r28).
Three zones are defined: activation zone DOnZ, dead band NZ and deactivation zone DOffZ, in which the program behaves differently (see the figure).
In the activation zone DonZ, the fans are started as follows:
- The inverter is activated as soon as there is demand, with a value no less than the minimum inverter opening MinIn;
- The inverter output is increased according to the times set by parameter r23.
- If the inverter output reaches 100%, the situation persists
In the dead band NZ, the inverter output does not undergo any variation.
In the deactivation zone DoffZ, the fans are stopped as follows:
- The inverter output is progressively brought to the minimum value, according to the times set by parameter r24.
When reaching the minimum value, the fans are stopped.
Key:
InPress
Discharge pressure
B Set point + differential
StpM HP set point
DOnZ Activation zone
DOffZ Deactivation zone
NZ Dead band
T [s] Time
Inverter Inverter status
NFan Number of fans on
Fig. 5.f
/
