Danfoss vlt aqua Guide

Contents
1. How to Read this Design Guide
3
Copyright, Limitation of Liability and Revision Rights 3
Approvals 4
Symbols 4
Abbreviations 5
Definitions 5
2. Introduction to the VLT AQUA Drive 11
Disposal Instructions 12
CE labeling 13
Air humidity 15
Aggressive Environments 15
Vibration and shock 16
VLT AQUA Controls 20
PID 22
General aspects of EMC 32
Galvanic isolation (PELV) 35
Ground leakage current 36
Control with brake function 36
Mechanical brake control 38
Extreme running conditions 38
Safe Stop Operation 40
3. VLT AQUA Selection 43
General Specifications 43
Line Supply 3 x 200-240 V AC 43
Line Supply 3 x 380-480 V AC 47
Efficiency 55
Special Conditions 60
Purpose of derating 60
Automatic adaptations to ensure performance 63
Mechanical Dimension 64
Options and Accessories 65
Analog I/O option MCB 109 71
4. How to Order 77
Ordering form 77
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Type Code String 78
Ordering Numbers 79
5. How to Install 83
Mechanical Installation 83
Accessory Bag 83
Electrical Installation 85
Removal of Knockouts for Extra Cables 85
Access to Control Terminals 92
Electrical Installation, Control Terminals 93
Final Set-Up and Test 97
Final Set-Up and Test 97
Safe Stop Installation 99
Safe Stop Commissioning Test 100
Additional Connections 100
Installation of misc. connections 104
Safety 107
EMC-correct Installation 108
Residual Current Device 112
6. Application Examples 113
7. RS-485 Installation and Set-up 123
RS-485 Installation and Set-up 123
FC Protocol Overview 126
Network Configuration 127
FC Protocol Message Framing Structure 127
Examples 133
Modbus RTU Overview 135
VLT AQUA with Modbus RTU 136
Modbus RTU Message Framing Structure 136
How to Access Parameters 141
Examples 142
Danfoss FC Control Profile 148
8. Troubleshooting 155
Index
162
Contents VLT
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AQUA Drive Design Guide
2 MG.20.N2.22 - VLT®is a registered Danfoss trademark.

1. How to Read this Design Guide
1.1.1. Copyright, Limitation of Liability and Revision Rights
This publication contains information proprietary to Danfoss A/S. By accepting and using this
manual, the user agrees that the information contained herein will be used solely for operating
equipment from Danfoss A/S or equipment from other vendors, provided that such equipment is
intended for communication with Danfoss equipment over a serial communication link. This pub-
lication is protected under the copyright laws of Denmark and most other countries.
Danfoss A/S does not guarantee that a software program produced according to the guidelines
provided in this manual will function properly in every physical, hardware or software environment.
Although Danfoss A/S has tested and reviewed the documentation within this manual,
Danfoss A/S makes no warranty or representation, neither expressed nor implied, with respect to
this documentation, including its quality, performance or fitness for a particular purpose.
In no event shall Danfoss A/S be liable for direct, indirect, special, incidental or consequential
damages arising from the use or the inability to use information contained in this manual, even if
advised of the possibility of such damages. In particular, Danfoss A/S is not responsible for any
costs, including, but not limited to, those incurred as a result of lost profits or revenue, loss of or
damages to equipment, loss of computer programs, loss of data, the costs to substitute these, or
any claims by third parties.
Danfoss A/S reserves the right to revise this publication at any time and to make changes to its
contents without prior notice or any obligation to notify former or present users of such revisions
or changes.
This design guide will introduce all aspects of your VLT AQUA Drive.
Available literature for the VLT AQUA
Drive
-The Instruction Manual MG.20.MX.YY provides the necessary information for getting the
drive up and running.
-Drive Design Guide MG.20.NX.YY contains all the technical information about the drive,
customer design and applications.
-Programming Guide MG.20.0X.YY provides information on how to program and includes
complete parameter descriptions.
X = Revision number
YY = Language code
Danfoss Drives technical literature is also available online at www.danfoss.com/BusinessAreas/
DrivesSolutions/Documentations/Technical+Documentation.
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1.1.2. Approvals
1.1.3. Symbols
Symbols used in this guide.
NOTE
Indicates something to be noted by the reader.
Indicates a general warning.
Indicates a high-voltage warning.
*Indicates default setting
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1.1.4. Abbreviations
Alternating current AC
American wire gauge AWG
Ampere/AMP A
Automatic Motor Adaptation AMA
Current limit ILIM
Degrees Celsius °C
Direct current DC
Drive Dependent D-TYPE
Electro Magnetic Compatibility EMC
Electronic Thermal Relay ETR
drive FC
Gram g
Hertz Hz
Kilohertz kHz
Local Control Panel LCP
Meter m
Milli Henry Inductance mH
Milliampere mA
Millisecond ms
Minute min
Motion Control Tool MCT
Nanofarad nF
Newton Meters Nm
Nominal motor current IM,N
Nominal motor frequency fM,N
Nominal motor power PM,N
Nominal motor voltage UM,N
Parameter par.
Protective Extra Low Voltage PELV
Printed Circuit Board PCB
Rated Inverter Output Current IINV
Revolutions Per Minute RPM
Second s
Torque limit TLIM
Volt V
1.1.5. Definitions
Drive:
I
VLT,MAX
The maximum output current.
I
VLT,N
The rated output current supplied by the adjustable frequency drive.
U
VLT, MAX
The maximum output voltage.
Input:
Control command
You can start and stop the connected motor using
the LCP and the digital inputs.
Functions are divided into two groups.
Functions in group 1 have higher priority than
functions in group 2.
Group 1 Reset, Coasting stop, Reset and Coasting
stop, Quick stop, DC braking, Stop and the
"Off" key.
Group 2 Start, Pulse start, Reversing, Start reversing,
Jog and Freeze output
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Motor:
f
JOG
The motor frequency when the jog function is activated (via digital terminals).
f
M
The motor frequency.
f
MAX
The maximum motor frequency.
f
MIN
The minimum motor frequency.
f
M,N
The rated motor frequency (nameplate data).
I
M
The motor current.
I
M,N
The rated motor current (nameplate data).
n
M,N
The rated motor speed (nameplate data).
P
M,N
The rated motor power (nameplate data).
T
M,N
The rated torque (motor).
U
M
The instantaneous motor voltage.
U
M,N
The rated motor voltage (nameplate data).
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AQUA Drive Design Guide
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η
VLT
The efficiency of the adjustable frequency drive is defined as the ratio between the power output
and the power input.
Start-disable command
A stop command belonging to the group 1 control commands - see this group.
Stop command
See Control commands.
References:
Analog Reference
A signal transmitted to the analog inputs 53 or 54 can be voltage or current.
Bus Reference
A signal transmitted to the serial communication port (FC port).
Preset Reference
A defined preset reference to be set from -100% to +100% of the reference range. Selection of
eight preset references via the digital terminals.
Pulse Reference
A pulse frequency signal transmitted to the digital inputs (terminal 29 or 33).
Ref
MAX
Determines the relationship between the reference input at 100% full scale value (typically 10 V,
20 mA) and the resulting reference. The maximum reference value set in par. 3-03.
Ref
MIN
Determines the relationship between the reference input at 0% value (typically 0V, 0 mA, 4 mA)
and the resulting reference. The minimum reference value set in par. 3-02.
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Miscellaneous:
Analog Inputs
The analog inputs are used for controlling various functions of the adjustable frequency drive.
There are two types of analog inputs:
Current input, 0-20 mA and 4-20 mA
Voltage input, 0-10 V DC.
Analog Outputs
The analog outputs can supply a signal of 0-20 mA, 4-20 mA, or a digital signal.
Automatic Motor Adaptation, AMA
AMA algorithm determines the electrical parameters for the connected motor at standstill.
Brake Resistor
The brake resistor is a module capable of absorbing the braking energy generated in regenerative
braking. This regenerative braking energy increases the intermediate circuit voltage, and a brake
chopper ensures that the energy is transmitted to the brake resistor.
CT Characteristics
Constant torque characteristics used for positive displacement pumps and blowers.
Digital Inputs
The digital inputs can be used for controlling various functions of the adjustable frequency drive.
Digital Outputs
The drive features two solid state outputs that can supply a 24 V DC (max. 40 mA) signal.
DSP
Digital Signal Processor.
Relay Outputs:
The adjustable frequency drive features two programmable relay outputs.
ETR
Electronic Thermal Relay is a thermal load calculation based on present load and time. Its purpose
is to estimate the motor temperature.
GLCP:
Graphical Local Control Panel (LCP102)
Initializing
If initializing is carried out (par. 14-22), the programmable parameters of the adjustable frequency
drive return to their default settings.
Intermittent Duty Cycle
An intermittent duty rating refers to a sequence of duty cycles. Each cycle consists of an on-load
and an off-load period. The operation can be either periodic duty or non-periodic duty.
1. How to Read this Design Guide VLT
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AQUA Drive Design Guide
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LCP
The Local Control Panel (LCP) makes up a complete interface for control and programming of the
adjustable frequency drive. The control panel is detachable and can be installed up to 9.8 ft (3
meters) from the adjustable frequency drive, i.e. in a front panel by means of the installation kit
option.
The local control panel is available in two versions:
-Numerical LCP101 (NLCP)
-Graphical LCP102 (GLCP)
lsb
Least significant bit.
MCM
Short for Mille Circular Mil, an American measuring unit for cable cross-section. 1 MCM 0.00079≡
in.
2
(0.5067 mm
2
).
msb
Most significant bit.
NLCP
Numerical Local Control Panel LCP101
Online/Offline Parameters
Changes to online parameters are activated immediately after the data value is changed. Changes
to offline parameters are not activated until you enter [OK] on the LCP.
PID Controller
The PID controller maintains the desired speed, pressure, temperature, etc. by adjusting the out-
put frequency to match the varying load.
RCD
Residual Current Device.
Set-up
You can save parameter settings in four set-ups. Change between the four parameter set-ups and
edit one set-up while another set-up is active.
SFAVM
Switching pattern called Stator Flux oriented Asynchronous Vector Modulation (par. 14-00).
Slip Compensation
The adjustable frequency drive compensates for the motor slip by giving the frequency a supple-
ment that follows the measured motor load, thus keeping the motor speed almost constant.
Smart Logic Control (SLC)
The SLC is a sequence of user-defined actions executed when the associated user-defined events
are evaluated as true by the SLC.
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Thermistor:
A temperature-dependent resistor placed where the temperature is to be monitored (adjustable
frequency drive or motor).
Trip
A state entered in fault situations, such as when the adjustable frequency drive is subject to an
overtemperature, or when the adjustable frequency drive is protecting the motor, process or
mechanism. Restart is prevented until the cause of the fault has disappeared and the trip state is
cancelled by activating reset or, in some cases, by being programmed to reset automatically. Trip
may not be used for personal safety.
Trip-Locked
A state entered in fault situations when the adjustable frequency drive is protecting itself and
requires physical intervention, such as when it is subject to a short circuit on the output. A locked
trip can only be cancelled by cutting off AC line power, removing the cause of the fault, and
reconnecting the adjustable frequency drive . Restart is prevented until the trip state is cancelled
by activating reset or, in some cases, by being programmed to reset automatically. The trip-lock
function may not be used as a personal safety measure.
VT Characteristics
Variable torque characteristics used for pumps and fans.
VVCplus
Compared with standard voltage/frequency ratio control, Voltage Vector Control (VVC
plus
) im-
proves the dynamics and the stability, both when the speed reference is changed and in relation
to the load torque.
60° AVM
Switching pattern called 60° Asynchronous Vector Modulation (par. 14-00).
1.1.6. Power Factor
The power factor is the relation between I
1
and I
RMS
.
Power factor =
3× U × I
1× COS ϕ
3× U × IRMS
The power factor for 3-phase control:
=
I
1×
cos ϕ1
IRMS
=
I
1
IRMS
since cos
ϕ1=1
The power factor indicates to which extent the
adjustable frequency drive imposes a load on
the line supply.
The lower the power factor, the higher the
I
RMS
for the same kW performance.
IRMS = I
2
1+
I
2
5+
I
2
7+..+
I
2
n
In addition, a high power factor indicates that the different harmonic currents are low.
The adjustable frequency drive's built-in DC coils produce a high power factor, which minimizes
the imposed load on the line power supply.
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2. Introduction to the VLT AQUA Drive
2.1. Safety
2.1.1. Safety note
The voltage of the adjustable frequency drive is dangerous whenever connected to
line power. Incorrect installation of the motor, adjustable frequency drive or serial
communication bus may cause damage to the equipment, serious personal injury or
death. Consequently, the instructions in this manual, as well as national and local
rules and safety regulations, must be followed.
Safety Regulations
1. The adjustable frequency drive must be disconnected from line power if repair work is to be
carried out. Make sure that the line supply has been disconnected and that the necessary time
has passed before removing motor and line plugs.
2. The [STOP/RESET] key on the control panel of the adjustable frequency drive does not dis-
connect the equipment from line power and is thus not to be used as a safety switch.
3. Correct protective grounding of the equipment must be established, the user must be protected
against supply voltage, and the motor must be protected against overload in accordance with
applicable national and local regulations.
4. The ground leakage currents are higher than 3.5 mA.
5. Protection against motor overload is set by par. 1-90
Motor Thermal Protection . If this function
is desired, set par. 1-90 to data value [ETR trip] (default value) or data value [ETR warning]. Note:
The function is initialized at 1.16 x rated motor current and rated motor frequency. For the North
American market: The ETR functions provide class 20 motor overload protection in accordance
with NEC.
6. Do not remove the plugs for the motor and line supply while the adjustable frequency drive is
connected to line power. Make sure that the line supply has been disconnected and that the
necessary time has passed before removing motor and line plugs.
7. Please note that the adjustable frequency drive has more voltage inputs than L1, L2 and L3
when load sharing (linking of DC intermediate circuit) and external 24 V DC have been installed.
Make sure that all voltage inputs have been disconnected and that the necessary time has passed
before commencing repair work.
Installation at High Altitudes
At altitudes higher than 6,600 feet [2 km], please contact Danfoss Drives regarding
PELV.
Warning against Unintended Start
1. The motor can be brought to a stop by means of digital commands, bus commands, references
or a local stop while the adjustable frequency drive is connected to line power. If personal safety
considerations make it necessary to ensure that no unintended start occurs, these stop functions
are not sufficient. 2. While parameters are being changed, the motor may start. Consequently,
the stop key [STOP/RESET] must always be activated, following which data can be modified. 3.
A motor that has been stopped may start if faults occur in the electronics of the adjustable fre-
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quency drive, or if a temporary overload or a fault in the supply line or the motor connection
ceases.
Warning:
Touching the electrical parts may be fatal - even after the equipment has been dis-
connected from line power.
Also, make sure that other voltage inputs have been disconnected, such as external 24 V DC, load
sharing (linkage of DC intermediate circuit), as well as the motor connection for kinetic backup.
Refer to VLT
®
AQUA Drive Instruction Manual MG.20.MX.YY for further safety guidelines.
2.1.2. Caution
The adjustable frequency drive DC link capacitors remain charged after power has
been disconnected. To avoid the risk of electric shock, disconnect the adjustable
frequency drive from line power before performing maintenance procedures. Wait
at least as long as follows before servicing the adjustable frequency drive:
Voltage Min. Waiting Time
4 min. 15 min.
200 - 240 V 1.5-4 hp [1.1-3.7 kW] 7.5-60 hp [5.5-45 kW]
380 - 480 V 1.5-10 hp [1.1-7.5 kW] 15-125 hp [11-90 kW]
Be aware that there may be high voltage on the DC link even when the LEDs are turned off.
2.1.3. Disposal Instructions
Equipment containing electrical components may not be disposed of
together with domestic waste.
It must be collected separately as electrical and electronic waste in
accordance with local and currently valid legislation.
2. Introduction to the VLT AQUA Drive VLT
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2.2. Software Version
VLT AQUA Drive
Design Guide
Software version: 1.00
This Design Guide can be used for all VLT AQUA adjustable frequency drives with software
version 1.00.
The software version number can be seen in parameter 15-43.
2.3. CE labeling
2.3.1. CE Conformity and Labeling
What is CE Conformity and Labeling?
The purpose of CE labeling is to avoid technical trade obstacles within the EFTA and the EU. The
EU has introduced the CE label as a simple way of showing whether a product complies with the
relevant EU directives. The CE label says nothing about the specifications or quality of the product.
Adjustable frequency drives are regulated by three EU directives:
The machinery directive (98/37/EEC)
All machines with critical moving parts are covered by the Machinery Directive of January 1, 1995.
Since an adjustable frequency drive is largely electrical, it does not fall under the Machinery Di-
rective. However, if an adjustable frequency drive is supplied for use in a machine, we provide
information on its safety aspects in the manufacturer's declaration.
The low-voltage directive (73/23/EEC)
Adjustable frequency drives must be CE-labeled in accordance with the Low-voltage Directive of
January 1, 1997. The directive applies to all electrical equipment and appliances used in the
50-1000 V AC and the 75-1500 V DC voltage ranges. Danfoss uses CE labels in accordance with
the directive and will issue a declaration of conformity upon request.
The EMC directive (89/336/EEC)
EMC is short for electromagnetic compatibility. The presence of electromagnetic compatibility
means that the mutual interference between different components/appliances does not affect the
way the appliances work.
The EMC directive came into effect January 1, 1996. Danfoss uses CE labels in accordance with
the directive and will issue a declaration of conformity upon request. To carry out EMC-correct
installation, see the instructions in this Design Guide. In addition, we specify the standards with
which our products comply. We offer the filters presented in the specifications and provide other
types of assistance to ensure the optimum EMC result.
The adjustable frequency drive is most often used by professionals of the trade as a complex
component forming part of a larger appliance, system or installation. It must be noted that the
responsibility for the final EMC properties of the appliance, system or installation rests with the
installer.
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2.3.2. What Is Covered
The EU " Guidelines on the Application of Council Directive 89/336/EEC " outline three typical sit-
uations of using an adjustable frequency drive. See below for EMC coverage and CE labeling.
1. The adjustable frequency drive is sold directly to the end-consumer. For example, it may
be sold to a DIY market. The end-consumer is a layman. He installs the adjustable fre-
quency drive himself for use with a hobby machine, a kitchen appliance, etc. For such
applications, the adjustable frequency drive must be CE-labeled in accordance with the
EMC directive.
2. The adjustable frequency drive is sold for installation in a plant. The plant is built up by
professionals of the trade. It could be a production plant or a heating/ventilation plant
designed and installed by professionals of the trade. Neither the adjustable frequency
drive nor the finished plant must be CE-labeled under the EMC directive. However, the
unit must comply with the basic EMC requirements of the directive. This is ensured by
using components, appliances and systems that are CE-labeled under the EMC directive.
3. The adjustable frequency drive is sold as part of a complete system. The system is being
marketed as complete and could, for example, be an air-conditioning system. The com-
plete system must be CE-labeled in accordance with the EMC directive. The manufacturer
can ensure CE-labeling under the EMC directive either by using CE-labeled components
or by testing the EMC of the system. If he chooses to use only CE-labeled components,
he does not have to test the entire system.
2.3.3. Danfoss VLT Adjustable Frequency Drive and CE Labeling
CE labeling is a positive feature when used for its original purpose, i.e. to facilitate trade within
the EU and EFTA.
However, CE labeling may cover many different specifications. Thus, you must check what a given
CE label specifically covers.
The covered specifications can be very different and a CE label may therefore give the installer a
false sense of security when using an adjustable frequency drive as a component in a system or
an appliance.
Danfoss CE labels the adjustable frequency drives in accordance with the low-voltage directive.
This means that if the adjustable frequency drive is installed correctly, we guarantee compliance
with the low-voltage directive. Danfoss issues a declaration of conformity that confirms our CE
labeling in accordance with the low-voltage directive.
The CE label also applies to the EMC directive provided that the instructions for EMC-correct in-
stallation and filtering are followed. On this basis, a declaration of conformity in accordance with
the EMC directive is issued.
The Design Guide offers detailed instructions for installation to ensure EMC-correct installation.
Furthermore, Danfoss specifies which our different products comply with.
Danfoss gladly provides other types of assistance that can help you obtain the best EMC result.
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2.3.4. Compliance with EMC Directive 89/336/EEC
As mentioned, the adjustable frequency drive is mostly used by professionals of the trade as a
complex component forming part of a larger appliance, system or installation. It must be noted
that the responsibility for the final EMC properties of the appliance, system or installation rests
with the installer. To assist the installer, Danfoss has prepared EMC installation guidelines for the
Power Drive system. The standards and test levels stated for power drive systems are complied
with, provided that the EMC-correct instructions for installation are followed; see the section
Electrical Installation .
2.4. Air humidity
The adjustable frequency drive has been designed to meet the IEC/EN 60068-2-3 standard, EN
50178 pkt. 9.4.2.2 at 122° F [50° C].
2.5. Aggressive Environments
An adjustable frequency drive contains a large number of mechanical and electronic components.
All are vulnerable to environmental effects to some extent.
The adjustable frequency drive should not be installed in environments with airborne
liquids, particles or gases capable of affecting and damaging the electronic compo-
nents. Failure to take the necessary protective measures increases the risk of
stoppages, thus reducing the life of the adjustable frequency drive.
Liquids can be carried through the air and condense in the adjustable frequency drive and may
cause corrosion of components and metal parts. Steam, oil and salt water may cause corrosion
of components and metal parts. In such environments, use equipment with enclosure rating IP
55. As an extra protection, coated printet circuit boards can be ordered as an option.
Airborne particles such as dust may cause mechanical, electrical or thermal failure in the adjustable
frequency drive. A typical indicator of excessive levels of airborne particles is the presence of dust
particles around the adjustable frequency drive fan. In very dusty environments, use equipment
with enclosure rating IP 55 or a cabinet for IP 00/IP 20/TYPE 1 equipment.
In environments with high temperatures and humidity, corrosive gases such as sulfur, nitrogen
and chlorine compounds will cause chemical processes on the adjustable frequency drive com-
ponents.
Such chemical reactions will rapidly affect and damage the electronic components. In such envi-
ronments, mount the equipment in a cabinet with fresh air ventilation, keeping aggressive gases
away from the adjustable frequency drive.
An extra protection in such areas is a coating of the printed circuit boards, which can be ordered
as an option.
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NOTE
Mounting adjustable frequency drives in aggressive environments increases the risk
of stoppages and considerably reduces the life of the drive.
Before installing the adjustable frequency drive, check the ambient air for liquids, particles and
gases. This is done by observing existing installations in this environment. A typical indicator of
harmful airborne liquids is the presence of water or oil on metal parts, or the corrosion of metal
parts.
Excessive dust particle levels are often found on installation cabinets and existing electrical in-
stallations. One indicator of aggressive airborne gases is the blackening of copper rails and cable
ends on existing installations.
2.6. Vibration and shock
The adjustable frequency drive has been tested according to the procedure based on the shown
standards:
The adjustable frequency drive complies with requirements that exist for units mounted on the
walls and floors of production premises, as well as in panels bolted to walls or floors.
IEC/EN 60068-2-6: Vibration (sinusoidal) - 1970
IEC/EN 60068-2-64: Vibration, broad-band random
2.7. Advantages
2.7.1. Why use an adjustable frequency drive for controlling fans and
pumps?
An adjustable frequency drive takes advantage of the fact that centrifugal fans and pumps follow
the laws of proportionality for such fans and pumps. For further information, see
The Laws of
Proportionality
text.
2.7.2. The clear advantage - energy savings
The very clear advantage of using an adjustable frequency drive for controlling the speed of fans
or pumps lies in the electricity savings.
Compared to alternative control systems and technologies, an adjustable frequency drive is the
optimum energy control system for controlling fan and pump systems.
2.7.3. Example of energy savings
As can be seen from the figure (the laws of proportionality), the flow is controlled by changing
the rpm. By reducing the rated speed by only 20%, the flow is also reduced by 20%. This is
because the flow is directly proportional to the rpm. The consumption of electricity, however, is
reduced by 50%.
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If the system in question only needs to be able to supply a flow corresponding to 100% a few
days each year, while the average is below 80% of the rated flow for the remainder of the year,
the amount of energy saved is even greater than 50%.
The laws of proportionality
This figure describes the dependence of flow, pressure and power consumption on rpm.
Q = Flow P = Power
Q
1
= Rated flow P
1
= Rated power
Q
2
= Reduced flow P
2
= Reduced power
H = Pressure n = Speed regulation
H
1
= Rated pressure n
1
= Rated speed
H
2
= Reduced pressure n
2
= Reduced speed
Flow :
Q
1
Q
2
=
n
1
n
2
Pressure :
H
1
H
2
=
(
n
1
n
2
)
2
Power :
P
1
P
2
=
(
n
1
n
2
)
3
2.7.4. Example with varying flow over 1 year
The example below is calculated on the basis of pump characteristics obtained from a pump da-
tasheet.
The result obtained shows energy savings in excess of 50% at the given flow distribution over a
year. The pay back period depends on the price per kwh and the price of the adjustable frequency
drive. In this example, it is less than a year when compared with valves and constant speed.
VLT
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AQUA Drive Design Guide 2. Introduction to the VLT AQUA Drive
MG.20.N2.22 - VLT®is a registered Danfoss trademark. 17
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Pump characteristics Energy savings
P
shaft
=P
shaft output
Flow distribution over 1 year
m
3
/h Distribution Valve regulation Adjustable frequency drive
control
% Hours Power Consumption Power Consumption
A
1
- B
1
kWh A
1
- C
1
kWh
350 5 438 42,5 18.615 42,5 18.615
300 15 1314 38,5 50.589 29,0 38.106
250 20 1752 35,0 61.320 18,5 32.412
200 20 1752 31,5 55.188 11,5 20.148
150 20 1752 28,0 49.056 6,5 11.388
100 20 1752 23,0 40.296 3,5 6.132
Σ100 8760 275.064 26.801
2.7.5. Better control
If an adjustable frequency drive is used for controlling the flow or pressure of a system, improved
control is obtained.
An adjustable frequency drive can vary the speed of the fan or pump, thereby obtaining variable
control of flow and pressure.
Furthermore, an adjustable frequency drive can quickly adapt the speed of the fan or pump to
new flow or pressure conditions in the system.
Simple control of process (flow, level or pressure) utilizing the built-in PID control.
2. Introduction to the VLT AQUA Drive VLT
®
AQUA Drive Design Guide
18 MG.20.N2.22 - VLT®is a registered Danfoss trademark.
2

2.7.6. Cos φcompensation
Generally speaking, an adjustable frequency drive with a cos φof 1 provides power factor cor-
rection for the cos φof the motor, which means that there is no need to make allowance for the
cos φof the motor when sizing the power factor correction unit.
2.7.7. Star/delta starter or soft-starter not required
When larger motors are started, it is necessary in many countries to use equipment that limits the
start-up current. In more traditional systems, a star/delta starter or soft-starter is widely used.
Such motor starters are not required if an adjustable frequency drive is used.
As illustrated in the figure below, an adjustable frequency drive does not consume more than rated
current.
1 = VLT AQUA Drive
2 = Star/delta starter
3 = Soft-starter
4 = Start directly on line power
VLT
®
AQUA Drive Design Guide 2. Introduction to the VLT AQUA Drive
MG.20.N2.22 - VLT®is a registered Danfoss trademark. 19
2

2.8. VLT AQUA Controls
2.8.1. Control Principle
An adjustable frequency drive rectifies AC voltage from line into DC voltage, after which DC voltage
is converted into an AC current with a variable amplitude and frequency.
The motor is supplied with variable voltage / current and frequency, which enables infinitely var-
iable speed control of three-phased, standard AC motors.
2.8.2. Control Structure
Control structure in open-loop and closed-loop configurations:
In the configuration shown in the illustration above, par. 1-00 is set to Open-loop [0]. The resulting
reference from the reference handling system is received and fed through the ramp limitation and
speed limitation before being sent to the motor control. The output of the motor control is then
limited by the maximum frequency limit.
Select
Closed-loop [3] in par. 1-00 to use the PID controller for closed-loop control of, e.g., flow,
level or pressure in the controlled application. The PID parameters are located in par. group 20-
**.
2.8.3. Local (Hand On) and Remote (Auto On) Control
The adjustable frequency drive can be operated manually via the local control panel (LCP) or
remotely via analog and digital inputs and serial bus.
If allowed in par. 0-40, 0-41, 0-42, and 0-43, it is possible to start and stop the adjustable fre-
quency drive via the LCP using the [Hand ON] and [Off] keys. Alarms can be reset via the [RESET]
key. After pressing the [Hand On] key, the adjustable frequency drive goes into hand mode and
follows (as default) the local reference set by using the LCP arrow keys.
2. Introduction to the VLT AQUA Drive VLT
®
AQUA Drive Design Guide
20 MG.20.N2.22 - VLT®is a registered Danfoss trademark.
2