Daikin EWYD-BZ User manual

parteinvert
Air Cooled chiller/heat pump with screw compressors
EWYD_BZ
REV
01
Date
November 2020
Supersedes
D-EOMCP00104-14EN
Operating Manual
D-EOMCP00104-14_01EN

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TABLE OF CONTENTS
1SAFETY CONSIDERATIONS......................................................................................................................................... 4
1.1 General....................................................................................................................................................................4
1.2 Before switching the unit......................................................................................................................................... 4
1.3 Avoid electrocution.................................................................................................................................................. 4
2ABOUT THIS DOCUMENT............................................................................................................................................. 5
2.1 Contents..................................................................................................................................................................5
2.2 Revision history....................................................................................................................................................... 5
2.3 Abbreviations used..................................................................................................................................................5
2.4 References.............................................................................................................................................................. 5
3CONTROL SYSTEM DESCRIPTION ............................................................................................................................. 6
3.1 Architecture............................................................................................................................................................. 6
3.2 Main components.................................................................................................................................................... 7
3.3 Components operating limits ..................................................................................................................................8
4USING THE CONTROLLER ........................................................................................................................................... 9
4.1 Mask tree............................................................................................................................................................... 10
4.2 Measure units........................................................................................................................................................11
4.3 Default passwords.................................................................................................................................................11
5WORKING WITH THIS UNIT ........................................................................................................................................ 12
5.1 Controller purpose................................................................................................................................................. 12
5.2 Unit enabling ......................................................................................................................................................... 12
5.3 Unit modes............................................................................................................................................................ 12
5.4 Setpoints management .........................................................................................................................................13
5.4.1 4-20mA setpoint override .............................................................................................................................13
5.4.2 OAT setpoint override................................................................................................................................... 13
5.4.3 Return setpoint override ...............................................................................................................................14
5.5 Compressors capacity control............................................................................................................................... 14
5.5.1 Automatic Control.........................................................................................................................................14
5.5.2 Manual Control ............................................................................................................................................. 16
5.6 Compressors timing ..............................................................................................................................................19
5.7 Compressors protection........................................................................................................................................19
5.8 Compressors startup procedure ...........................................................................................................................19
5.9 Fan pre-starting in heating mode.......................................................................................................................... 19
5.10 Prepurge procedure with electronic expansion.....................................................................................................19
5.11 Prepurge procedure with thermostatic expansion ................................................................................................19
5.12 Oil heating.............................................................................................................................................................19
5.13 Energy Saving mode............................................................................................................................................. 20
5.14 Pumpdown ............................................................................................................................................................ 20
5.15 Low ambient temperature start .............................................................................................................................20
5.16 Economizer valve..................................................................................................................................................20
5.17 Switch between cooling and heating mode .......................................................................................................... 20
5.17.1 Switching from cooling modes to eating mode.............................................................................................20
5.17.1.1 Compressor running in cooling mode.................................................................................................. 20
5.17.1.2 Compressor stopped in cooling mode .................................................................................................20
5.17.2 Switching from heating modes to cooling modes ......................................................................................... 21
5.17.2.1 Compressor running in heating mode.................................................................................................. 21
5.17.2.2 Compressor stopped in heating mode.................................................................................................21
5.17.3 Additional consideration ............................................................................................................................... 21
5.18 Defrost procedure ................................................................................................................................................. 21
5.19 Liquid injection ......................................................................................................................................................21
5.20 Heat Recovery procedure .....................................................................................................................................21
5.20.1 Recovery pump ............................................................................................................................................21
5.20.2 Recovery control...........................................................................................................................................22
5.20.3 Compressor limiting...................................................................................................................................... 22
5.21 Unit limiting............................................................................................................................................................ 23
5.22 Evaporator pumps.................................................................................................................................................23
5.23 Fans control .......................................................................................................................................................... 23
5.23.1 Fantroll.......................................................................................................................................................... 23
5.23.1.1 Fantroll in cooling mode....................................................................................................................... 24
5.23.1.2 Fantroll in heating mode ...................................................................................................................... 24

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5.23.2 Variable Speed Driver .................................................................................................................................. 25
5.23.2.1 VSD in cooling, cooling glycol or ice mode..........................................................................................25
5.23.2.2 VSD in heating mode........................................................................................................................... 26
5.23.3 Speedtroll...................................................................................................................................................... 26
5.23.4 Fans control at startup in heating mode .......................................................................................................26
5.24 Other functions...................................................................................................................................................... 26
5.24.1 Hot Chilled Water Start.................................................................................................................................26
5.24.2 Fan Silent Mode ...........................................................................................................................................26
5.25 Unit and compressors status ................................................................................................................................26
5.26 Start-up sequence................................................................................................................................................. 28
5.26.1 Unit start-up and shut-down flowcharts........................................................................................................28
5.26.2 Heat recovery start-up and shut-down flowcharts........................................................................................ 30
6ALARMS AND TROUBLESHOOTING......................................................................................................................... 32
6.1 Unit trips................................................................................................................................................................ 32
6.2 Compressors trip...................................................................................................................................................32
6.3 Other trips.............................................................................................................................................................. 33
6.4 Unit and compressors alarms and corresponding codes......................................................................................33

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1 SAFETY CONSIDERATIONS
1.1 General
Installation, start-up and servicing of equipment can be hazardous if certain factors particular to the installation are not
considered: operating pressures, presence of electrical components and voltages and the installation site (elevated plinths
and built-up up structures). Only properly qualified installation engineers and highly qualified installers and technicians,
fully trained for the product, are authorized to install and start-up the equipment safely.
During all servicing operations, all instructions and recommendations, which appear in the installation and service
instructions for the product, as well as on tags and labels fixed to the equipment and components and accompanying parts
supplied separately, must be read, understood and followed.
Apply all standard safety codes and practices.
Wear safety glasses and gloves.
Do not operate on a faulty fan, pump or compressor before the main switch has been shut off.
Overtemperature protection is auto-reset, therefore the protected component may restart
automatically if temperature conditions allow it.
In some unit a push button is placed on a door of the unit electrical panel. The button is highlighted by a red color in yellow
background. A manual pressure of the emergency stop button stops all loads from rotating, thus preventing any accident
which may occur. An alarm is also generated by the Unit Controller. Releasing the emergency stop button enables the
unit, which may be restarted only after the alarm has been cleared on the controller.
The emergency stop causes all motors to stop but does not switch off power to the unit. Do not
service or operate on the unit without having switched off the main switch.
1.2 Before switching the unit
Before switching on the unit read the following recommendations:
•When all the operations and all the settings have been carried out, close all the switchbox panels
•The switchbox panels can only be opened by trained personnel
•When the UC requires to be accessed frequently the installation of a remote interface is strongly recommended
•LCD display of the unit controller may be damaged by extremely low temperatures (see chapter 2.4). For this
reason, it is strongly recommended to never power off the unit during winter, especially in cold climates.
1.3 Avoid electrocution
Only personnel qualified in accordance with IEC (International Electrotechnical Commission) recommendations may be
permitted access to electrical components. It is particularly recommended that all sources of electricity to the unit be shut
off before any work is begun. Shut off main power supply at the main circuit breaker or isolator.
IMPORTANT: This equipment uses and emits electromagnetic signals. Tests have shown that the equipment
conforms to all applicable codes with respect to electromagnetic compatibility.
Direct intervention on the power supply can cause electrocution, burns or even death. This action
must be performed only by trained persons.
RISK OF ELECTROCUTION: Even when the main circuit breaker or isolator is switched off, certain
circuits may still be energized, since they may be connected to a separate power source.
RISK OF BURNS: Electrical currents cause components to get hot either temporarily or permanently.
Handle power cable, electrical cables and conduits, terminal box covers and motor frames with great
care.
ATTENTION: In accordance with the operating conditions the fans can be cleaned periodically. A fan
can start at any time, even if the unit has been shut down.

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2 ABOUT THIS DOCUMENT
2.1 Contents
This document contains information and instructions to operate the control panel of EWYD_BZ units starting from
application software version ASDU30A.
2.2 Revision history
Version
Date
Validity
D-EOMCP00104-14_01EN
November 2020
Application software version ASDU30A and further
D-EOMCP00104-14EN
April 2014
Application software versions up to ASDU29A
2.3 Abbreviations used
A/C
Air Cooled
CP
Condensing Pressure
CSRT
Condensing Saturated Refrigerant Temperature
DSH
Discharge Superheat
DT
Discharge Temperature
E/M
Energy Meter Module
EEWT
Evaporator Entering Water Temperature
ELWT
Evaporator Leaving Water Temperature
EP
Evaporating Pressure
ESRT
Evaporating Saturated Refrigerant Temperature
EXV
Electronic Expansion Valve
HMI
Human Machine Interface
MOP
Maximum operating pressure
SSH
Suction SuperHeat
ST
Suction Temperature
UC
Unit controller (Microtech II)
W/C
Water Cooled
2.4 References
•pCO5plus +0300020EN rel. 1.6 - 10.07.2019 –Carel S.p.A
•“EVD evolution” +0300005EN - rel. 3.7 - 16.12.2019 –Carel S.p.A
•cod. +050003265 rel. 1.1 - 31.03.2004 –Carel S.p.A.

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3 CONTROL SYSTEM DESCRIPTION
3.1 Architecture
The overall control system architecture is described in the following picture:
Board
Model
Function
Mandatory
pCO Controller #1
pCO5+ “Large”
Built In display (*)
Unit control
Compressors #1 & #2 control
Y
pCO Controller #2
pCO5 “Small”
Compressors #3
Yes on 3
compressors units
pCOeEXP #1
pCOe
Additional hardware for compressors #1 & 2 or
for compressors #3
N
pCOeEXP #2
pCOe
Heat recovery or Heat pump control
N
pCOeEXP #3
pCOe
Water pump control
N
pCOeEXP #4
pCOe
Additional fan steps for compressors #1 & #2 or
for compressors #3
N
EEXV driver #1
EVD Evolution
Electronic expansion valve control for
compressor #1
Y
EEXV driver #2
EVD Evolution
Electronic expansion valve control for
compressor #2
Y
EEXV driver #3
EVD Evolution
Electronic expansion valve control for
compressor #3
Yes on 3
compressors units
Additional display
PGD
Special characters or additional display
N
(*) The contemporaneous presence of built-in display and additional PGD may be accepted.
CAUTION: Maintain the correct polarity when connecting the power supply to the boards, otherwise
the peripheral bus communication will not operate and the boards may be damaged.

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3.2 Main components
Unit controller
“EVD Evolution” - Electronic Expansion Valves controller

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3.3 Components operating limits
Component
Temperature [°C]
r.H. non-condensing [%]
pCO5+ (built-in display)
-20 ÷ 60
< 90
pCO5+
-40 ÷ 70
< 90
EVD Evolution
N.A.
< 90
pCOe
-10 ÷ 60
< 90
“EVD Evolution” - Electronic Expansion Valves controller –Graphic Display
“pCOe” - I/O Expansion board

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4 USING THE CONTROLLER
Two types of user interface are implemented in the software: built-in display and PGD; the PGD display is used as optional
remote display.
Both interfaces have a 4x20 LCD display and a 6 keys keypad.
Built-In Display
PGD Display
Key
Built-In
PGD
From Main Menu go-to
Alarm
Alarms submenu
Program
View submenu
Up
Settings submenu
Down
Maint submenu
Built-In & PGD navigation
Entering any other section different menus or mask loops are shown. From every loop with or key it is possible
to access the father menu and so on until main menu is reached.
In each loop horizontal navigation have been introduced.
In a mask with different I/O fields, with ENTER key is possible to access the first one, then with UP and DOWN it is possible
to increase and decrease respectively the value.The possibility of change values is subordinated to passwords of different
levels depending on the sensibility of the value.

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When a password is active, pressing UP+DOWN it is possible to reset all passwords (to make the access to protected
values not accessible anymore without the re-insertion of the password). In any main loops it is possible to change the
password for the corresponding level (Unit Config for Tech password, User Setpoint for Operator password and Maint
Setpoint for Manager password).
4.1 Mask tree
In the picture below the structure of the mask tree beginning from the main menu is shown. Masks loops of the same group
of parameters can be accessed using left and right arrows creating also horizontal loops. Parameters within a same
horizontal loop could accessed with a unique password. In violet the loop horizontally linked are shown. All loops could be
accessed directly from the main menu. Once in the selected loop the other loops, with the same colour in the previous
scheme, could be reached with left and right arrows. This will mean for example that from the loop Unit Configuration it will
be possible to move to Unit Setpoint pressing the right arrow. Loops with no link with other loops could be accessed only
from the menu.
HMI structure

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4.2 Measure units
The interface is able to work using SI and Imperial units. In the the following units are used:
Measurement
Units
SI system
Imperial system
Pressure
bar
psi
Temperature
°C
°F
Time
sec
sec
As far as pressure is concerning, the interface shows if shown data are gauge or absolute using the postfix “g” or “a”
respectively.
4.3 Default passwords
Several levels of passwords for each subsection are available. Subsections are listed in the table below.
Section
Password
Super User
Daikin Use Only
Technician
Authorized Personnel can Contact Factory
Operator
0100

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5 WORKING WITH THIS UNIT
5.1 Controller purpose
Then system will control the evaporator leaving water temperature to keep it at a setpoint value.
The system operates to optimize components performances from the point of view of their efficiency and of their duration.
The system assures a safe operation of the unit and of all components and prevents dangerous situations.
5.2 Unit enabling
The control allows different ways to enable/disable the unit:
•Keypad: Enter key on the keypad allows to switch between “Power OFF” mode and “Unit On” if other signals
allows this state
•Local Switch: when the digital input “Unit On/Off” is open the unit is in “Local switch Off”; when the digital input
“Unit On/Off” is closed the unit may be in “Unit On” or “Remote switch Off” on the basis of the “Remote On/Off “
digital input
•Remote Switch: when the local switch is On (“Unit On/Off” digital input closed) if the digital input “Remote On/Off
“ is closed the unit is in “Unit On”, when digital input “Remote On/Off “ is open the unit is in “Remote switch Off”
•Network: a BAS or a Monitoring system may send an On/Off signal trough the serial line connection to put the
unit on or in “Rem. Comm. Off”
•Time schedule : a timetable allows to program “Time Schedule Off” on a week base; several holiday days are
include.
•Ambient LockOut : the unit is not enabled to operate unless the ambient temperature is higher than an adjustable
value (default 15.0°C (59.0 F) )
To be in “Unit On” all the allowed signals must enable the unit.
5.3 Unit modes
The unit is able to work in the following modes:
•Cooling. When this mode is selected the control will operate to cool the evaporator water; the setpoint range is +4.0
+14.0 °C, (39.2 57.2 F) a freeze alarm setpoint is set to 2 °C (34.6 F) (adjustable by the operator in the range +1
+3 °C (33.8 37.4 F) ) and a freeze prevent setpoint is set to 3 °C (37.4 F) (adjustable by the operator in the range:
“freeze alarm setpoint” + 1 +3 °C (“freeze alarm setpoint” + 1.8 F 37.4 F) ).
•Cooling/Glyco. When this mode is selected the control will operate to cool the evaporator water; the setpoint range
are -8°C +14.0°C (17.6 57.2 F) , a freeze alarm setpoint are set to –10 °C (14.0 F) (adjustable by the operator
in the range –12 °C -9°C (10.4 15.8 F) ) and a freeze prevent setpoint are set to –9 °C (15.8 F) (adjustable by the
operator in the range “freeze alarm setpoint” + 1°C -9 °C (“freeze alarm setpoint” + 1.8 F 15.8 F))
•Ice. When this mode is selected the control will operate to cool the evaporator water; the setpoint range are -8°C 
+14.0°C (17.6 57.2 F) , a freeze alarm setpoint are set to –10 °C (14.0 F) (adjustable by the operator in the range
–12 °C -9°C (10.4 15.8 F) ) and a freeze prevent setpoint are set to –9 °C (15.8 F) (adjustable by the operator in
the range “freeze alarm setpoint” + 1°C -9 °C (“freeze alarm setpoint” + 1.8 F 15.8 F)). While working in ice mode
compressors are not be allowed to unload but are stopped using a step procedure (se § 5.5.1)
•Heating. When this mode is selected the control will operate to heat the evaporator water; the setpoint range is +30
+45°C (86 113°C), a hot water alarm setpoint are set to 50°C (adjustable by the operator in the range +46 +55°C
(114.8 131 F) ) and a hot prevent setpoint are set to 48°C (118.4 F) (adjustable by the operator in the range +46°C
“hot water alarm setpoint” + 1°C (114.8 F “hot water alarm setpoint” + 1.8 F)).
•Cooling + Heat Recovery. Setpoints and freeze protection are managed as described in the coolingmode; inaddition
the control will enable the heat recovery input and outputs foreseen on the expansion #2
•Cooling/Glycol + Heat Recovery. Setpoints and freeze protection are managed as described in the cooling/glycol
mode; in addition the control will enable the heat recovery input and outputs foreseen on the expansion #2.
•Ice + Heat Recovery. Setpoints and freeze protection are managed as described in the ice mode; in addition the
control will enable the heat recovery input and outputs foreseen on the expansion #2.

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The selection between cooling, cooling/glycol and ice mode are performed by the operator using the interface under
password. The switching between cooling and ice and heating modes will cause the unit shutdown and than the switching
between the two modes.
5.4 Setpoints management
The control is able to manage the evaporator leaving water temperature on the base of several inputs:
•Changing the setpoint from the keypad
•Switching between the main setpoint (set by keypad) and an alternative value (set by keypad to) on the base of a
digital input state (double setpoint function)
•Receiving a setpoint by a monitoring system or a BAS connected via serial line
•Resetting the setpoint of the base of analogic inputs
The control shows the source of the used (Actual) setpoint:
Local
the main setpoint set by keypad is being used
Double
the alternative setpoint set by keypad is being used
Reset
the setpoint is being reset by external input
The following setpoint reset methods are available to modify the local or double setpoint:
None
local or double setpoint are used on the base of the double setpoint digital input.
This is called “base setpoint”
4-20mA
base setpoint is modified on the base of an user analog input
OAT
base setpoint is modified on the base of outside ambient temperature (if available)
Return
base setpoint is modified on the base of evaporator entering temperature
Network
the setpoint sent by serial line is used
In the case of a failure in the serial connection or in the 4-20mA input the base setpoint is used. In case of a setpoint reset,
the system display will show the type of reset.
5.4.1 4-20mA setpoint override
The base setpoint is modified on the base of the value of the analog input and of a max reset value, as shown in the picture
below:
5.4.2 OAT setpoint override
To enable the OAT setpoint override the unit limiting control expansion board pCOe#2 is required, with the ambient sensor
installed. The base setpoint is modified on the base of outside ambient temperature and of a max reset value, of a value
of OAT to start reset and a value of OAT to apply max reset, as shown in the picture below:
Max Reset
0 ma 4 mA 20 mA

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5.4.3 Return setpoint override
The base setpoint is modified on the base of evaporator T and of a max reset value, of a value of OAT to start reset and
a value of OAT to apply max reset, as shown in the picture below:
5.5 Compressors capacity control
Two types of capacity control are implemented:
•Automatic: the compressor start/stop and its capacity are automatically managed by the software to allow the setpoint
respect
•Manual: the compressor is started by the operator and its capacity is managed by the operator acting on the system
terminal. In this case the compressor will not be used by the software to allow the setpoint respect.
Manual control is automatically switched to Automatic control if any safety action is required on the compressor (safety
standby or unloading or safety shutdown). If this case the compressor remains in Automatic and must be re-switched to
Manual by the operator if required. Compressors in manual mode are automatically switched in automatic mode at their
shutdown. The compressor load by may be evaluated on the basis of:
•Calculation of loading and unloading pulses
•Analogic slide valve position signal (optional)
5.5.1 Automatic Control
A specialized PID algorithm is used to determinate the magnitude of corrective action on capacity control solenoid. The
compressor loading or unloading is obtained keeping the loading or unloading solenoid energized for a fixed time (pulse
duration), while the time interval between two subsequent pulses are evaluated by a PD controller. If the output of the PD
algorithm doesn’t change, the time interval among pulses is constant; this is the integral effect of the controller, at a
constant error the action is repeated with a constant time (with the additional feature of a variable integral time). The
0
Max
Reset
Start Reset T
Reset Delta T
OAT
0
Start Reset T
Max Reset
Reset Delta T
Evap T
Used Setpoint
Used Setpoint

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compressor load evaluation (based on analog slide valve position or calculation
1
) is used to allow the start of another
computer or the stop of a running one. It is required to define the proportional band and the derivative time of the PD
control, together with the pulse duration and a minimum and maximum value for pulses interval.
The minimum pulse interval is applied when the maximum correction action is required, while the maximum interval is
applied when the minimum correction action is required. A dead band is introduced to allow to reach a stable compressor
condition. Fig. 12 shows the proportional action of the controller as a function of the input parameters.
The proportional gain of the PD controller is given by:
2
RegBand
Max=
p
K
The derivative gain of the PD controller is equal to:
dpd TKK =
where Tdis the input derivative time.
In addition to the specialized PID controller, a max pull-down-rate is introduced in the control; this meanings that if the
controlled temperature is approaching the setpoint with a rate greater than a set value, any loading action is inhibited, even
if require by the PID algorithm. This makes the control slower but allows to avoid oscillations around setpoint. The controller
is designed to act both as a “chiller” and as a “heat pump”; when the “chiller” option is selected the controller will load t he
compressor if the measured temperature is above the setpoint and will unload the compressor if the measured temperature
is below the setpoint. When the “heat pump” option is selected the controller will load the compressor if the measured
temperature is below the setpoint and will unload the compressor if the measured temperature is above the setpoint. The
starting sequence of compressors is selected on the base oflower working hours amount (it means that the first compressor
that is started is the one with the lower amount of working hour); between two compressors with the same operating hours,
the compressor with minimum number of starts will start first. A manual sequencing of compressors is possible. The start
of the first compressor is allowed only if the absolute value of difference between the measured temperature and the
setpoint exceeds a Startup T value. The stop of the last compressor is allowed only if the absolute value of the difference
between the measured temperature and the setpoint exceeds a Shutdown T value.
A FILO (First In - Last Off) logic is adopted.
The start/loading and unloading/stop sequence will follow the schemes in table 2 and table 3, where RDT is the
Reload/Reunload T, a set value (that represent the minimum difference between the evaporator leaving water
temperature and its setpoint) that will a running compressor to be reload when a compressor is shutdown or a running
compressor to be unload when a new compressor is started.
This is made to keep the unit total capacity at the same level when the evaporator leaving water temperature is close to
the setpoint and a compressor stops, or another compressor starts, is required.
In Ice mode, while the compressor loading is not affected, the compressors downloading is inhibited. When downloading
is required compressors are shutdown on the basis of the evaporator leaving water temperature. In particular, said Stp the
evaporator leaving temperature setpoint, SDT the shutdown T value and n the number of compressors, the scheme in
table 6 is used. In addition when the heat pump option is installed, the compressor could be managed using a variable
speed driver (inverter). An analog output of pCO3board is used to control the compressor speed with a 0-10V signal. Load
management will still determine the time distance between load/unload pulses where pulse in this case means relative
variation of the output voltage. The magnitude of the variation could be adjusted under manufacturer password.
When the unit is working in heating mode the maximum speed will be the nominal speed (default value 67Hz).
When the unit is working in cooling mode an overboost option (activated either with the digital input 2 on the expansion
board #2 or automatically if the outside ambient temperature is greater than 35°C and disabled when it falls below 34°C)
is managed. It allows the compressor to run at its full speed of 90Hz if the maximum available capacity is reached. When
the overboost is disabled the valve opening (if the electronic expansion valve).
1
The calculation is based on the load increase (or decrease) associated to each pulse:
pulseloadn
pulseperIncLoad 25100 (%) − =
pulseunloadn
pulseperDecLoad 25100 (%) − =
Being “n load pulses” and “n unload pulses” the number of pulses to load and unload the compressor.
Counting the number of pulses given to the compressor its load is evaluated.

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Fixed pulse duration
Variable pulse interval
Loading or unloading pulses
Measure
Action
Set Point
Dead Band
Regulation Band
Max
0
-Max
PD controller proportional action
5.5.2 Manual Control
The control will apply a fixed duration pulse (the magnitude is the pulse duration set in the automatic control) for each
manual (by keyboard) load or unload signal.
In the manual control the load/unload action follows any pressing of defined up/down keys.
Load/Unload key press
Load/Unload pulse

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Table 2 - Compressors startup and loading management (4 compressors unit)
Step n.
Leader Comp.
Lag 1 Comp.
Lag 2 Comp.
Lag 3 Comp.
0
Off
Off
Off
Off
1
If (T –SetP) < Startup DT & Cooling
or (SetP - T) < Startup DT & Heating
… Waiting …
2
Start
Off
Off
Off
3
Load up to 75%
Off
Off
Off
4
If T in Regulation Band
… Wait interstage time …
5
If T is approaching SetP
… Waiting …
6a
SetP-RDT<T< SetP-RDT
Unload up to 50%
Start
Off
Off
6b
SetP-RDT<T or T> SetP-RDT
Fixed at 75%
Start
Off
Off
7
Fixed at
75% or 50%
Load up to 50%
Off
Off
8
(if leader at 50%)
Load up to 75%
Fixed at 50%
Off
Off
9
Fixed at 75%
Load up to 75%
Off
Off
10
If T in Regulation Band
… Wait interstage time …
11
If T is approaching SetP
… Waiting …
12a
SetP-RDT<T< SetP-RDT
Fixed at 75%
Unload up to 50%
Start
Off
12b
SetP-RDT<T or T> SetP-RDT
Fixed at 75%
Fixed at 75%
Start
Off
13
Fixed at 75%
Fixed at 75% or 50%
Load up to 50%
Off
14
(if lag1 at 50%)
Fixed at 75%
Load up to 75%
Fixed at 50%
Off
15
Fixed at 75%
Fixed at 75%
Load up to 75%
Off
16
If T in Regulation Band
… Wait interstage time …
17
If T is approaching SetP
… Waiting …
18a
SetP-RDT<T< SetP-RDT
Fixed at 75%
Fixed at 75%
Unload up to 50%
Start
18b
SetP-RDT<T or T> SetP-RDT
Fixed at 75%
Fixed at 75%
Fixed at 75%
Start
17
Fixed at 75%
Fixed at 75%
Fixed at 75% or
50%
Load up to 50%
18
(if lag2 at 50%)
Fixed at 75%
Fixed at 75%
Load up to 75%
Fixed at 50%
19
Fixed at 75%
Fixed at 75%
Fixed at 75%
Load up to 75%
20
Load up to 100%
Fixed at 75%
Fixed at 75%
Fixed at 75%
21
Fixed at 100%
Load up to 100%
Fixed at 75%
Fixed at 75%
22
Fixed at 100%
Fixed at 100%
Load up to 100%
Fixed at 75%
23
Fixed at 100%
Fixed at 100%
Fixed at 100%
Load up to 100%
24
Fixed at 100%
Fixed at 100%
Fixed at 100%
Fixed at 100%

D-EOMCP00104-14_01EN
Operating Manual
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EWYD_BZ
Table 3 - Compressors unloading and shutdown management (3 compressors unit)
Step n.
Leader Comp.
Lag 1 Comp.
Lag 2 Comp.
0
100%
100%
100%
1
Fixed at 100%
Fixed at 100%
Fixed at 100%
2
Fixed at 100%
Fixed at 100%
Unload up to 75%
3
Fixed at 100%
Unload up to 75%
Fixed at 75%
4
Unload up t75%
Fixed at 75%
Fixed at 75%
5
Fixed at 75%
Fixed at 75%
Fixed at 75%
6
Fixed at 75%
Fixed at 75%
Unload up to 50%
7
Fixed at 75%
Fixed at 75%
Fixed at 50%
8
If T is approaching SetP
… Waiting …
9a
SetP-RDT<T< SetP-RDT
Fixed at 75%
Fixed at 75%
Load up to 75%
9b
SetP-RDT<T or T> SetP-RDT
Fixed at 75%
Fixed at 75%
Fixed at
10
(if lag2 at 75%)
Fixed at 75%
Fixed at 75%
Fixed at
11
Fixed at 75%
Unload up to 50%
Fixed at 50%
12
Fixed at 75%
Fixed at 50%
Fixed at 25%
13
If T is approaching SetP
… Waiting …
14a
SetP-RDT<T< SetP-RDT
Fixed at 75%
Load up to 75%
Stop
14b
SetP-RDT<T or T> SetP-RDT
Fixed at 75%
Fixed at 50%
Stop
15
(if lag1 at 75%)
Fixed at 75%
Unload up to 50%
Off
16
Unload up to 50%
Fixed at 50%
Off
17
Fixed at 50%
Unload up to 25%
Off
18
If T is approaching SetP
… Waiting …
19a
SetP-RDT<T< SetP-RDT
Load up to 75%
Stop
Off
19b
SetP-RDT<T or T> SetP-RDT
Fixed at 50%
Stop
Off
20
Unload up to 25%
Off
Off
21
If T is approaching SetP
… Waiting …
22
If (SetP - T) < Shutdown DT & Cooling
OR
If (T –SetP)< Shutdown DT & Heating THEN….Wait….
23
Stop
Off
Off
24
Off
Off
Off

Operating Manual
D-EOMCP00104-14_01EN
EWYD_BZ
19/35
Table 4 - Compressors shutdown scheme in Ice mode (3 compressors unit)
Evap Lvg Temp
Compressors status
SetP –SDT/n < Evap Lvg Temp < SetP
All compressors allowed to run
SetP –2*SDT/n < Evap Lvg Temp < SetP–SDT/n
(n-1) compressors allowed to run
SetP –3*SDT/n < Evap Lvg Temp < SetP –2*SDT/n
(n-2) compressors allowed to run
SetP –4*SDT/n < Evap Lvg Temp < SetP –3*SDT/n
No compressor allowed to run
5.6 Compressors timing
Compressors operation will meet four timer requirements:
•Minimum time between a same compressor starts (start to start timer): it is the minimum time between two starts of
the same compressor
•Minimum time between different compressor starts: it is the minimum time between two starts of two different
compressors
•Minimum time compressor on (start to stop timer): it is the minimum time the compressor may run; the compressor
cannot be stopped (unless an alarm occurs) if this timer is not expired
•Minimum time compressor off (stop to start timer): it is the minimum time the compressor may be stopped; the
compressor cannot be start if this timer is not expired
The minimum time compressor off (stop to start timer) will has two different settings; one applicable to cooling,
cooling/glycol and heating mode and the other one applicable in ice mode.
5.7 Compressors protection
To protect compressor against loss of lubrication, the compressor pressure ratio is continuously checked; a minimum value
is set for compressor minimum and maximum load; for intermediate compressor loads a linear interpolation are executed.
Thelow pressure ratioalarm will occur ifpressure ratio remains lower than the minimum value at rated compressor capacity
while a timer expiration.
At the startup the compressor is completely downloaded and its loading will not be enabled up to the pressure ratio exceeds
a set value (default equal to 2).
5.8 Compressors startup procedure
Before to start compressors the unloading solenoid valve is energized up to a timer is expired (default 60 sec).
At compressor startup the control will executed a series of prepurge procedure to evacuate evaporator; the prepurge
procedure will depend on the expansion valve type.
Prepurge procedure will not be executed if the evaporating pressure is below the low pressure alarm setpoint (vacuum
conditions inside the evaporator).
The compressor will not be allowed to load up to the discharge superheat exceeds a set value (default 12.2 °C, 22 F) for
a time longer than a set value (default 30 sec) .
5.9 Fan pre-starting in heating mode
When the unit is operated in heating mode, if the outside ambient temperature is lower than an fixed threshold of 10.0°C
(50.0F) before the compressor is started and the start-up procedure is initiated all fans are started with a constant delay
between each other.
5.10 Prepurge procedure with electronic expansion
At the compressor start the EEXV are completely closed up to the saturated temperature at the evaporator pressure
reaches the value of –10 °C (14 F) (adjustable in the range –12 -4 °C (10.4 24.8 F) ), then the valve are opened at a
fixed position (adjustable by the manufacturer with a default value equal to 20%) up to a timer is expired (default 30 sec).
5.11 Prepurge procedure with thermostatic expansion
At the compressor start the liquid line solenoid is completely closed up to the saturated temperature at the evaporator
pressure reaches the value of –10°C (14 F) (adjustable in the range –12 -4 °C (10.4 24.8 F)), then the valve is opened
up to a timer is expired; this procedure is repeated for a number of times adjustable by the operator (default is 1 time).
5.12 Oil heating
The startup of compressors will not be allowed if the following formula is not respected:
DischTemp –TOilPress > 5 °C

D-EOMCP00104-14_01EN
Operating Manual
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EWYD_BZ
Where:
DischTemp is the compressor discharge temperature
TOilPress is the saturated temperature at the oil pressure
5.13 Energy Saving mode
The energy saving function reduces the power consumption deactivating the compressors crankcase heater, when the
chiller is Disabled. This mode implies that the time needed to start the compressors, after an Off period, could be delayed
until a maximum of 90 minutes.
For time critical application, the energy saving function can be disabled by the user to ensure the compressor start within
1 minute from unit On command.
5.14 Pumpdown
As a compressor stop request is recorded (and if the request doesn’t originate from an alarm), before to proceed, the
compressor is fully discharged and operated for a certain amount of time with a closed expansion valve (in the case of
electronic expansion valve) or closed liquid line valve (in the case of thermostatic expansion valve).
This operation, known as “pumpdown”, is used to evacuate the evaporator avoiding that in a following restart the
compressor will such liquid.
Pumpdown procedure will end after a user defined timer is expired (adjustable, default 30 sec.) or the saturated
temperature at the evaporator pressure reaches the value of –10°C (adjustable in the range –12 -4 °C (10.4 24.8 F) ).
After compressor stop the unloading solenoid valve are energized for a time equal to the minimum compressor off time to
assure the complete unloading also in case of non-normal stop procedure completion.
5.15 Low ambient temperature start
Units working in cooling, cooling/glycol or ice mode has to manage start-up with low outside ambient temperature.
A low OAT start is initiated if, at the compressor start up, the condenser saturated temperature is less than 15.5 °C (60 F).
Once this happens, 3 seconds after the end compressor startup procedure (end of prepurge cycles) low pressure events
are disabled for a time equal to the low OAT time (setpoint has an adjustable range from 20 to 120seconds, defaults 120
sec.).
The absolute low pressure limit (the threshold which has no time delay) is still enforced. If this limit pressure is reached a
Low Ambient Start-Up low pressure alarm is issued.
At the end of the low OAT start, the evaporator pressure is checked. If the pressure is greater than or equal to the
evaporator pressure stage down setpoint, the start is considered successful. If the pressure is less than this, the start is
not successful and the compressor shall stop. Three start attempts are allowed before tripping on the restart alarm.
The restart counter should be reset when either a start is successful or the circuit is off on an alarm.
5.16 Economizer valve
If the option is present (expansion board 1) and enabled under manufacturer password, when the compressor’s load
percentage is greater than an adjustable threshold (default is 90%) and if the saturated condensing temperature is lesser
than an adjustable setpoint (default is 65.0°C ) the economizer valve is energized. The valve is deenergized if either the
compressor’s load percentage falls below another adjustable threshold (default is 75%) or if the saturated condensing
temperature falls below the setpoint minus an adjustable differential (default is 5.0 °C).
5.17 Switch between cooling and heating mode
Any time the switching of a compressor between cooling (or cooling/glycol or ice) and heating mode is require, either if this
is required by unit switching form one mode to other or to start defrost or to end defrost, the following procedures are
followed.
5.17.1 Switching from cooling modes to eating mode
5.17.1.1 Compressor running in cooling mode
A compressor running in cooling mode (four-way valve de-energized) is switched off without executing pumpdown, the
four-way valve is energized 5 seconds after the compressor has been switched off, than the compressor is switched on
after the minimum time compressor off is expired and the standard prepurge procedure is executed.
5.17.1.2 Compressor stopped in cooling mode
If a compressor that was stopped in cooling mode is required to start in heating mode it is switched on in standard cooling
mode (with four-way valve de-energized and executing the standard prepurge procedure), it is kept running for 120
seconds in cooling mode and than is switched off without pumpdown, the four-way valve is energized 5 seconds after the
compressor has been switched off, than the compressor is switched on after the minimum time compressor off is expired.