Copyright, Limitation of Liability and Revision Rights5
Symbols6
Abbreviations7
Definitions7
2 Introduction to VLT Automation VT Drive
CE labelling17
Vibration and shock19
Control Structures24
General aspects of EMC34
Immunity Requirements38
Galvanic isolation (PELV)39
PELV - Protective Extra Low Voltage39
Earth leakage current40
Control with Brake Function41
Control with Brake Function42
Mechanical Brake Control42
Extreme Running Conditions42
Safe Stop Operation (Optional)47
5
15
3 VLT Automation VT Drive Selection
General Specifications49
Efficiency65
Special Conditions72
Options and Accessories77
General Description89
High Power Options95
Installation of Duct Cooling Kit in Rittal Enclosures95
Outside Installation/ NEMA 3R Kit for Rittal Enclosures98
Installation on Pedestal99
Input Plate Option102
Installation of Mains Shield for Frequency Converters103
Frame size F Panel Options104
4 How to Order
Ordering Form107
Type Code String108
49
107
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ContentsAutomation VT Drive FC322 Design Guide
Ordering Numbers111
5 How to Install
Mechanical Installation125
Pre-installation131
Planning the Installation Site131
Receiving the Frequency Converter
Transportation and Unpacking131
Lifting132
Cooling and Airflow136
Electrical Installation140
Connections - Frame sizes D, E and F156
Power Connections156
Disconnectors, Circuit Breakers and Contactors170
Final Set-Up and Test171
Safe Stop Installation173
Safe Stop Commissioning Test174
Additional Connections176
Installation of Misc. Connections179
Safety181
EMC-correct Installation182
Residual Current Device186
125
131
6 Application Examples
Potentiometer Reference188
Automatic Motor Adaptation (AMA)188
SLC Application Example189
System Status and Operation192
Cascade Controller Wiring Diagram
Fixed Variable Speed Pump Wiring Diagram194
Lead Pump Alternation Wiring Diagram194
7 RS-485 Installation and Set-up
RS-485 Installation and Set-up197
FC Protocol Overview199
Network Configuration201
FC Protocol Message Framing Structure201
Examples209
Modbus RTU Overview210
187
193
197
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Automation VT Drive FC322 Design GuideContents
VLT Automation VT Drive with Modbus RTU210
Modbus RTU Message Framing Structure211
How to Access Parameters216
Examples217
Danfoss FC Control Profile222
8 Troubleshooting
231
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1 How to Read this Design GuideAutomation VT Drive FC322 Design Guide
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1 How to Read this Design Guide
1
1.1.1 Copyright, Limitation of Liability and Revision Rights
This publication contains information proprietary to Danfoss. By accepting and using this manual the user agrees that the information contained herein
will be used solely for operating equipment from Danfoss or equipment from other vendors provided that such equipment is intended for communication
with Danfoss equipment over a serial communication link. This publication is protected under the Copyright laws of Denmark and most other countries.
Danfoss does not warrant 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 has tested and reviewed the documentation within this manual, Danfoss 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 be liable for direct, indirect, special, incidental, or consequential damages arising out of the use, or the inability to use information
contained in this manual, even if advised of the possibility of such damages. In particular, Danfoss is not responsible for any costs, including but not
limited to those incurred as a result of lost profits or revenue, loss or damage of equipment, loss of computer programs, loss of data, the costs to substitute
these, or any claims by third parties.
Danfoss 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
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1 How to Read this Design GuideAutomation VT Drive FC322 Design Guide
1.1.3 Symbols
Symbols used in this guide.
NB!
Indicates something to be noted by the reader.
Indicates a general warning.
Indicates a high-voltage warning.
Indicates default setting
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Automation VT Drive FC322 Design Guide1 How to Read this Design Guide
1.1.4 Abbreviations
Alternating currentAC
American wire gaugeAWG
Ampere/AMPA
Automatic Motor AdaptationAMA
Current limitI
Degrees Celsius°C
Direct currentDC
Drive DependentD-TYPE
Electro Magnetic CompatibilityEMC
Electronic Thermal RelayETR
DriveFC
Gramg
HertzHz
KilohertzkHz
Local Control PanelLCP
Meterm
Millihenry InductancemH
MilliamperemA
Millisecondms
Minutemin
Motion Control ToolMCT
NanofaradnF
Newton MetersNm
Nominal motor currentI
Nominal motor frequencyf
Nominal motor powerP
Nominal motor voltageU
Parameterpar.
Protective Extra Low VoltagePELV
Printed Circuit BoardPCB
Rated Inverter Output CurrentI
Revolutions Per MinuteRPM
Regenerative terminalsRegen
Seconds
Synchronous Motor Speedn
Torque limitT
VoltsV
I
VLT,MAX
I
VLT,N
LIM
M,N
M,N
M,N
M,N
INV
s
LIM
The maximum output current
The rated output current supplied by the frequency converter
1
1.1.5 Definitions
Drive:
I
VLT,MAX
The maximum output current.
I
VLT,N
The rated output current supplied by the frequency converter.
U
VLT, MAX
The maximum output voltage.
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1 How to Read this Design GuideAutomation VT Drive FC322 Design Guide
Input:
Control command
You can start and stop the connected motor by means of
LCP and the digital inputs.
Functions are divided into two groups.
Functions in group 1 have higher priority than functions in
group 2.
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).
Group 1Reset, Coasting stop, Reset and Coasting stop, Quick-
stop, DC braking, Stop and the "Off" key.
Group 2Start, Pulse start, Reversing, Start reversing, Jog and
Freeze output
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Automation VT Drive FC322 Design Guide1 How to Read this Design Guide
VLT
The efficiency of the frequency converter 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, 20mA) and the resulting reference. The maximum
reference value set in par. 3-03.
1
Ref
MIN
Determines the relationship between the reference input at 0% value (typically 0V, 0mA, 4mA) and the resulting reference. The minimum reference value
set in par. 3-02.
Miscellaneous:
Analog Inputs
The analog inputs are used for controlling various functions of the frequency converter.
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 brake power generated in regenerative braking. This regenerative braking power increases the
intermediate circuit voltage and a brake chopper ensures that the power is transmitted to the brake resistor.
CT Characteristics
Constant torque characteristics used for positive displacement pumps and blowers.
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1 How to Read this Design GuideAutomation VT Drive FC322 Design Guide
Digital Inputs
The digital inputs can be used for controlling various functions of the frequency converter.
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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 frequency converter 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)
Initialising
If initialising is carried out (par. 14-22), the programmable parameters of the frequency converter return to their default set tings.
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 none-periodic duty.
LCP
The Local Control Panel (LCP) makes up a complete interface for control and programming of the frequency converter. The control panel is detachable
and can be installed up to 3 metres from the frequency converter, 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.
1
MCM
Short for Mille Circular Mil, an American measuring unit for cable cross-section. 1 MCM ิ 0.5067 mm
msb
Most significant bit.
NLCP
Numerical Local Control Panel LCP101
On-line/Off-line Parameters
Changes to on-line parameters are activated immediately after the data value is changed. Changes to off-line 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 output frequency to match the varying load.
RCD
Residual Current Device.
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.
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1 How to Read this Design GuideAutomation VT Drive FC322 Design Guide
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.
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SFAVM
Switching pattern called
S tator F lux oriented A synchronous V ector M odulation (par. 14-00).
Slip Compensation
The frequency converter compensates for the motor slip by giving the frequency a supplement that follows the measured motor load 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.
Thermistor:
A temperature-dependent resistor placed where the temperature is to be monitored (frequency converter or motor).
Trip
A state entered in fault situations, e.g. if the frequency converter is subject to an over-temperature or when the frequency converter 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 frequency converter is protecting itself and requiring physical intervention, e.g. if the frequency converter is
subject to a short circuit on the output. A locked trip can only be cancelled by cutting off mains, removing the cause of the fault, and reconnecting the
frequency converter. Restart is prevented until the trip state is cancelled by activating reset or, in some cases, by being programmed to reset automatically.
Trip locked may not be used for personal safety.
VT Characteristics
Variable torque characteristics used for pumps and fans.
plus
VVC
If compared with standard voltage/frequency ratio control, Voltage Vector Control (VVC
reference is changed and in relation to the load torque.
plus
) improves the dynamics and the stability, both when the speed
1
60° AVM
Switching pattern called 60°
A synchronous V ector M odulation (par. 14-00).
1.1.6 Power Factor
The power factor is the relation between I1 and I
The power factor for 3-phase control:
The power factor indicates to which extent the frequency converter im-
poses a load on the mains supply.
The lower the power factor, the higher the I
formance.
In addition, a high power factor indicates that the different harmonic currents are low.
The frequency converters' built-in DC coils produce a high power factor, which minimizes the imposed load on the mains supply.
.
RMS
for the same kW per-
RMS
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The voltage of the frequency converter is dangerous whenever connected to mains. Incorrect installation of the motor, frequency
converter or fieldbus 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 complied with.
Safety Regulations
1. The frequency converter must be disconnected from mains if repair work is to be carried out. Check that the mains supply has been disconnected and
that the necessary time has passed before removing motor and mains plugs.
2. The [STOP/RESET] key on the control panel of the frequency converter does not disconnect the equipment from mains and is thu s not to be used as
a safety switch.
3. Correct protective earthing 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 earth leakage currents are higher than 3.5 mA.
5. Protection against motor overload is set by par. 1-90
value) or data value [ETR warning]. Note: The function is initialised 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 mains supply while the frequency converter is connected to mains. Check that the mains supply has been
disconnected and that the necessary time has passed before removing motor and mains plugs.
7. Please note that the frequency converter 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. Check that all voltage inputs have been disconnected and that the necessary time has passed before commencing repair
work.
Installation at High Altitudes
Motor Thermal Protection
. If this function is desired, set par. 1-90 to data value [ETR trip] (default
2
By altitudes above 2 km, please contact Danfoss 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 frequency converter is
connected to mains. 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 frequency converter, or if a temporary overload or
a fault in the supply mains or the motor connection ceases.
Warning:
Touching the electrical parts may be fatal - even after the equipment has been disconnected from mains.
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 purpose of CE labelling is to avoid technical trade obstacles within 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. Frequency
converters 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 a frequency converter is largely electrical, it does
not fall under the machinery directive. However, if a frequency converter is supplied for use in a machine, we provide information on safety aspects
relating to the frequency converter. We do this by means of a manufacturer's declaration.
The low-voltage directive (73/23/EEC)
Frequency converters must be CE labelled 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 CE-labels in accordance with the directive and issues 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 CE-labels in accordance with the directive and issues a declaration of conformity upon
request. To carry out EMC-correct installation, see the instructions in this Design Guide. In addition, we specify which standards our products comply
with. We offer the filters presented in the specifications and provide other types of assistance to ensure the optimum EMC result.
The frequency converter 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.
2.3.2 What Is Covered
2
The EU "
Guidelines on the Application of Council Directive 89/336/EEC
coverage and CE labelling.
1.The frequency converter is sold directly to the end-consumer. The frequency converter is for example sold to a DIY market. The end-consumer
is a layman. He installs the frequency converter himself for use with a hobby machine, a kitchen appliance, etc. For such applications, the
frequency converter must be CE labelled in accordance with the EMC directive.
2.The frequency converter 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 frequency converter nor the finished plant has to be
CE labelled 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 labelled under the EMC directive.
3.The frequency converter is sold as part of a complete system. The system is being marketed as complete and could e.g. be an air-conditioning
system. The complete system must be CE labelled in accordance with the EMC directive. The manufacturer can ensure CE labelling under the
EMC directive either by using CE labelled components or by testing the EMC of the system. If he chooses to use only CE labelled components,
he does not have to test the entire system.
" outline three typical situations of using a frequency converter. See below for EMC
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2.3.3 Danfoss Frequency Converter and CE Labelling
CE labelling is a positive feature when used for its original purpose, i.e. to facilitate trade within the EU and EFTA.
However, CE labelling may cover many different specifications. Thus, you have to 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 feeling of security when using a frequency converter
as a component in a system or an appliance.
Danfoss CE labels the frequency converters in accordance with the low-voltage directive. This means that if the frequency converter is installed correctly,
we guarantee compliance with the low-voltage directive. Danfoss issues a declaration of conformity that confirms our CE labelling in accordance with the
low-voltage directive.
The CE label also applies to the EMC directive provided that the instructions for EMC-correct installation 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 prod-
ucts comply with.
Danfoss gladly provides other types of assistance that can help you obtain the best EMC result.
2.3.4 Compliance with EMC Directive 89/336/EEC
As mentioned, the frequency converter 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. As an
aid to 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
The frequency converter has been designed to meet the IEC/EN 60068-2-3 standard, EN 50178 pkt. 9.4.2.2 at 50°C.
A frequency converter contains a large number of mechanical and electronic components. All are to some extent vulnerable to environmental effects.
The frequency converter should not be installed in environments with airborne liquids, particles, or gases capable of affecting and
damaging the electronic components. Failure to take the necessary protective measures increases the risk of stoppages, thus reducing
the life of the frequency converter.
Liquids can be carried through the air and condense in the frequency converter 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 54/55. As an extra
protection, coated printed circuit boards can be ordered as an option.
Particles such as dust may cause mechanical, electrical, or thermal failure in the frequency converter. A typical indicator of excessive levels of
Airborne
airborne particles is dust particles around the frequency converter fan. In very dusty environments, use equipment with enclosure rating IP 54/55 or a
cabinet for IP 00/IP 20/TYPE 1 equipment.
In environments with high temperatures and humidity,
on the frequency converter components.
corrosive gases such as sulphur, nitrogen, and chlorine compounds will cause chemical processes
EMC Immunity
.
18
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Such chemical reactions will rapidly affect and damage the electronic components. In such environments, mount the equipment in a cabinet with fresh
air ventilation, keeping aggressive gases away from the frequency converter.
An extra protection in such areas is a coating of the printed circuit boards, which can be ordered as an option.
NB!
Mounting frequency converters in aggressive environments increases the risk of stoppages and considerably reduces the life of the
converter.
Before installing the frequency converter, check the ambient air for liquids, particles, and gases. This is done by observing existing installations in this
environment. Typical indicators of harmful airborne liquids are water or oil on metal parts, or corrosion of metal parts.
Excessive dust particle levels are often found on installation cabinets and existing electrical installations. One indicator of aggressive airborne gases is
blackening of copper rails and cable ends on existing installations.
NB!
D and E enclosures have a stainless steel back-channel option to provide additional protection in aggressive environments. Proper ventilation is still
required for the internal components of the drive. Contact Danfoss for additional information.
2
2.4 Vibration and shock
The frequency converter has been tested according to the procedure based on the shown standards:
The frequency converter 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
2.5 Advantages
2.7.1 Why use a Frequency Converter for Controlling Fans and Pumps?
A frequency converter 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 text
The Laws of Proportionality
2.7.2 The Clear Advantage - Energy Savings
The very clear advantage of using a frequency converter for controlling the speed of fans or pumps lies in the electricity savings.
When comparing with alternative control systems and technologies, a frequency converter is the optimum energy control system for controlling fan and
pump systems.
.
MG.20.X1.22 - VLTp is a registered Danfoss trademark
Illustration 2.1: The graph is showing fan curves (A, B and
C) for reduced fan volumes.
Illustration 2.2: When using a frequency converter to reduce
fan capacity to 60% - more than 50% energy savings may
be obtained in typical applications.
2.7.3 Example of Energy Savings
As can be seen from the figure (the laws of proportional ity), the flow is controlled by changing t he RPM. By reducing the speed only 20% from the rated
speed, 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%.
If the system in question only needs to be able to supply a flow that corresponds to 100% a few days in a year, while the average is below 80% of the
rated flow for the remainder of the year, the amount of energy saved is even more than 50%.
The laws of proportionality
The figure below describes the dependence of flow, pressure and power consumption on RPM.
Q = FlowP = Power
Q1 = Rated flowP1 = Rated power
Q
= Reduced flowP2 = Reduced power
2
H = Pressuren = Speed regulation
H1 = Rated pressuren1 = Rated speed
H
= Reduced pressuren2 = Reduced speed
2
20
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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 tr aditional systems, a star/
delta starter or soft-starter is widely used. Such motor starters are not required if a frequency converter is used.
2
As illustrated in the figure below, a frequency converter does not consume more than rated current.
1 = VLT Automation VT Drive
2 = Star/delta starter
3 = Soft-starter
4 = Start directly on mains
MG.20.X1.22 - VLTp is a registered Danfoss trademark
The frequency converter is a high performance unit for demanding applications. It can handle various kinds of motor control principles such as U/f special
motor mode and VVC plus and can handle normal squirrel cage asynchronous motors.
Short circuit behavior on this FC depends on the 3 current transducers in the motor phases.
par. 1-00 Configuration Mode
In
is to be used
it can be selected if open or closed lo op
2.8.2 Control Structure Open Loop
Illustration 2.4: Open Loop structure.
In the configuration shown in the illustration above,
handling system or the local reference is received and fed through the ramp limitation and speed limitation before being sent to the motor control.
The output from the motor control is then limited by the maximum frequency limit.
par. 1-00 Configuration Mode
is set to Open loop [0]. The resulting reference from the reference
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The closed loop controller allows the drive to become an integral part of the controlled system. The drive receives a feedback signal from a sensor in the
system. It then compares this feedback to a set-point reference value and determines the error, if any, between these two signals. It then adjusts the
speed of the motor to correct this error.
2
For example, consider a pump application where the speed of a pump is to be controlled so that the static pressure in a pipe is constant. The desired
static pressure value is supplied to the drive as the set-point reference. A static pressure sensor measures the actual static pressure in the pipe and
supplies this to the drive as a feedback signal. If the feedback signal is greater than the set-point reference, the drive will slow down to reduce the
pressure. In a similar way, if the pipe pressure is lower than the set-point reference, the drive will automatically speed up to increase the pressure provided
by the pump.
NB!
While the default values for the drive’s Closed Loop controller will often provide satisfactory performance, the control of the system
can often be optimized by adjusting some of the Closed Loop controller’s parameters. It is also possible to autotune the PI constants.
The figure is a block diagram of the drive’s Closed Loop controller. The details of the Reference Handling block and Feedback Handling block are described
in their respective sections below.
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A block diagram of how the drive processes the feedback signal is shown below.
2
Feedback handling can be configured to work with applications requiring advanced control, such as multiple setpoints and multiple feedbacks. Three
types of control are common.
Single Zone, Single Setpoint
Single Zone Single Setpoint is a basic configuration. Setpoint 1 is added to any other reference (if any, see Reference Handling) and the feedback signal
is selected using par. 20-20.
Multi Zone, Single Setpoint
Multi Zone Single Setpoint uses two or three feedback sensors but only one setpoint. The feedbacks can be added, subtracted (only feedback 1 and 2)
or averaged. In addition, the maximum or minimum value may be used. Setpoint 1 is used exclusively in this configuration.
Multi Setpoint Min
If
attempts to keep all zones at or below their respective setpoints, while
setpoints.
Example:
A two zone two setpoint application Zone 1 setpoint is 15 bar and the feedback is 5.5 bar. Zone 2 setpoint is 4.4 bar and the feedback is 4.6 bar. If
Setpoint Max
setpoint, resulting in a negative difference). If
has the larger difference (feedback is lower than setpoint, resulting in a positive difference).
[13] is selected, the setpoint/feedback pair with the largest difference controls the speed of the drive.
Multi Setpoint Min
[14] is selected, Zone 1’s setpoint and feedback are sent to the PID controller, since this has the smaller difference (feedbac k i s higher th an
Multi Setpoint Min
[13] is selected, Zone 2’s setpoint and feedback is sent to the PID controller, since this
[13] attempts to keep all zones at or above their respective
Multi Setpoint Maximum
[14]
Multi
MG.20.X1.22 - VLTp is a registered Danfoss trademark
In some applications it may be useful to convert the feedback signal. One example of this is using a pressure signal to provide flow feedback. Since the
square root of pressure is proportional to flow, the square root of the pressure signal yields a value proportional to the flow. This is shown below.
2.8.7 Reference Handling
Details for Open Loop and Closed Loop operation.
A block diagram of how the drive produces the Remote Reference is shown below:.
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MG.20.X1.22 - VLTp is a registered Danfoss trademark
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