VARIABLE FREQUENCY DRIVE CONTROLLER FOR 3PHASE INDUCTION MOTOR

CHAPTER-1

1.1INTRODUCTION

The project is about the conversion of single phase into three phase for drive utility. In
addition to this the drive also performs the functions like running the three phase induction
motor in forward direction, reverse direction, and in constant speed (jog). Also the drive is
able to sense the fault and issue the alarm signal.

Most commercial and industrial electrical equipment requires three phase power based on
electrical demand of heavy manufacturing population and general industry. In rural areas or
commercial office building that were not originally designed to support heavy manufacturing
utilities do not install three phase power because the cost is significantly more than single
phase installation.

For many years, people have been using different technology to generate three phase power
from single-phase supply sources. Common technology include rotary phase converter, static
converters and variable frequency drives. As initial investment costs of VLT drive have
lowered and product reliability has increased, more users are turning to VLT drive as the best
solution to convert single-phase motor applications to three-phase, because their process
demands have changed requiring variable speed control. Common applications utilizing VLT
drive with single-phase input are submersible well pumps, centrifugal pumps, irrigation
systems, fountain systems, and pump jacks [1].

In this project one such drive as VLTmicro drive is used as controller for three phase motor.

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CHAPTER-2

2.1. VLTMICRO DRIVE FC51:-

This chapter discuss the features, benefits, performance, protection, safety instruction,

advantage, disadvantage and application of the VLTmicro drive.

Fig2.1 VLT micro drive FC51

An AC drive is a device that is used to control the speed of an electrical motor. The speed is
controlled by changing the frequency of the electrical supply to the motor. The three-phase
voltage in national electrical grid connected to a motor creates a rotating magnetic field in it.

High quality components and genuine VLT® SOLUTIONS MAKES VLT® micro drive
extremely reliable. Important features of the drive is listed below.

 Optimum heat dissipation-longer lifetime.

 High quality electronics/capacitors-low lifetime cost

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 All drives full load tested from factory-high reliability

 Earth fault, temperature and short circuit protection-lean operation
 Circuit boards well protected and coated-increased robustness

2.2.BLOCK DIAGRAM OF VLT® MICRO DRIVE

The block diagram of the is shown in the figure shown below.

Fig2.2 block diagram of micro drive

The three major section of the collector are as the follows:

 BRIDGE RECTIFIER - rectifies the incoming single phase AC power and converts in
to DC
 CAPACITOR - provides a smooth rectified DC voltage.
 IGBT’S- The basic working principle of inverter is switching the DC on and off. The
switching is control to vary the frequency of simulated AC that is applied to the motor.
 AC motor characteristics require the applied voltage to be proportionally adjusted by
the VLT whenever the frequency is changed.

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2.3.FEATURES AND BENEFITS

 Side-by-side mounting without de rating is possible thanks to the compact, book-style

design

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 Penetration of dust is minimized thanks to coated PCBs

 Radio disturbance from motor cables is limited due to built –in RF filters
 Life time of the drive extended and reliability improved as a result of the effective s
heat from the electronics
 Energy consumption can be reduced as kinetic energy in the application can be
transformed into braking power to slow down the motor

2.4.HIGH PERFORMANCE

Despite the compact size and the easy commissioning, VLT® micro drive can be setup to
perform perfectly even in complex application set-ups. Approximately 100parameters can
be set to optimize energy efficiency and operation.

 Process PL-controller-no need for external controller

 Automatic energy optimizer(AEO)-less energy consumption
 Automatic motor adaptation(AMA)-exploit motors full potential
 150%motor torque up to 1 minute –replace need for bigger drive
 Flying start(catch a spinning motor)-lean operation-more up –time
 Electronic thermal relay (ETR)-replace external motor protection
 Smart logic controller-often makes PLC omissible, RFI filter save cost and space

2.5.PROTECTIONAL FEATURES

 Electronic motor thermal protection against overload.

 Temperature monitoring of the heat sink ensures that the frequency converter trips if
there is over temperature.
 The frequency converter is protected against short circuit between motor terminals U,
V, W.
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 When a motor phase is missing, the frequency converter trips and issues an alarm.
 When a mains phase is missing, the frequency converter trips or issues a warning
(depending on the load).
 Monitoring of the DC-link voltages ensures that the frequency converter trips when the
DC- link voltage is too low or too high.
 The frequency converter is protected against ground faults on motor terminals U, V, W.

2.6.SAFETY INSTRUCTION

 Make sure that the frequency converter is properly grounded.

 Do not remove main connections, motor connections, or other power connections while
the frequency converter is connected to power.
 Protect the motor against overloading according to national and local regulation.
 The ground leakage current exceeds 3.5 mA. Ground the frequency converter properly.
 The [off/reset] key is not a safety switch. It does not disconnected the frequency
converter.

2.7.ADVANTAGES OF AC DRIVES

 Ac drives are less expensive.

 Ac drives requires low maintenance.
 Ac drives are light in weight.
 Saves more energy

2.8.DISADVANTAGES OF AC DRIVES

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 Power converter for the control of ac drives are more complex.

 Power converter for ac drives are more expensive.
 Power converter for ac drives generate harmonics in the supply system and load
circuit.

2.9.APPLICATION OF AC DRIVE

 HVAC systems
 Water supply pump in power plant
 Boiler feed pump
 Energy saving on condensing water pump
 Hotel air conditioning fans
 Variable flow hydronic system
 Condensing pump of power generator
 Pumps on pressure booster system

CHAPTER-3

3.1.DRIVE INTERFACING AND TESTING

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This chapter discuss the drive interfacing, connecting mains and motors, estimation, testing and
troubleshoot.

Fig3.1.drive interfacing

The above figure shows the drive interfacing, the bridge rectifier converts AC input to DC
current and then simulates AC output since the output is conditioned by the VLT micro dive.
The electronics of the VLT micro drive will step up single phase current during the conversion
process. To do this, input power is first converted to DC current using bridge rectifier, and then
converted to the desired output current using capacitor and diodes. The DC supply which is fed
to the inverter converts DC supply into AC supply in the form of three wire, that is three phase
supply. After the conversion the three phase supply is given to load which is three phase
induction motor. A 3 phase motor is simply attaches to the appropriate output connectors of the
VLT micro drive.

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3.2.CONNECTING MAINS AND MOTORS

The frequency converter is designed to operate all standard 3-phased induction motors. The
frequency converter is designed to accept mains /motor cable

1. Mount the ground wires to PE terminal.

2. Connect motor to terminals U, V, and W.
3. Mount mains supply to terminals L1/L and L3/N (single –phase) and tighten.

Press [menu ] to select 1 of the following menus:

Status

For readouts only. Quick menu

For access to quick menus 1and 2.

Navigation keys

[back]: for moving to the previous steps or layers in the navigation structure.

[ꓥ] [ꓦ]: for manoeuvring between parameter groups, parameter and within parameters.

[ok]: for selecting a parameter and for accepting changes to parameter settings.

Pressing [ꓥ] [ꓦ]: to change value. Press[ok] to shift between digits quikly.

To exit adjust mode, press [ok] more than 1 again with changes savings or press [back] without
changes saving.

Operational keys

A yellow indicator light above the operation keys indicates the active key.

[hand on]: starts the motor and enables control of the frequency converter via the LCP.

[off/reset]: the motor stops. If in alarm mode, the motor resets.

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[Auto on]: the frequency converter is controlled either via control terminals or serial
communication.

[potentiometer ](LCP12): the potentiometer works in 2 ways depending on the mode in which
the frequency converter is running.

In auto On mode, the potentiometer acts as an extra programmable analog input.

In hand on mode, the potentiometer controls local reference[2].

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3.3.FABRICATION

It is the process, of assembling all gathered materials for the project.

Fig 3.3(a) fabrication of panel board

Process involves in making of panel board:-

 The panel boards of wood is cut in the size required by the stand, drive, motor,
terminals, switch.
 The panel boards then fixed to the stand with bolts and nuts.
 All the materials are assembled in right places in the board.
 VLT micro drive is fitted in the board.
 After, the installation of all equipments and materials as shown in below diagram.

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Fig 3.3(b) panel board

Fig 3.3(c) fabrication of panel board

Fig 3.3(d) panel board

Panel board size – 3 feet*1.5 feet

Cost - 170/- rupees

Fabrication size – 3 feet*2 feet

Cost – 450/- rupees

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3.4.FABRICATION INTERFACE PANEL

Fabrication interface panel has been designed.

Fig 3.4 fabrication interface panel

Which facilitates to evaluate the features of the following testing:-

 Forward rotation
 Reverse rotation
 Constant rotation (jog)
 Alarm

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3.5.ESTIMATION OF PROJECT

Estimation is nothing but before carrying out a work it is necessary to know probable cost of
materials and labour cost.

Sl no Particulars Unit Quantity Rate Cost Rs.Ps

Rs.Ps
1 VLT micro drive - 1 7500 7500

2 Induction motor rpm 1 2000 2000

3 Terminals nos 3 30 150

4 Alarm no 1 40 40

5 SP Switch nos 2 20 40

6 PVC board no 1 170 170

7 Screw nos 3 5 15

8 Bushes nos 4 5 20

9 Stand fabrication - 1 450 450

10 Radient cutting - - 440 440

11 Carpenter board cutting - 1 100 100

12 Miscellaneous charge - - 1500 1500

Total 12,250 12,425

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3.6.TESTING

In this section the testing of micro drive have been carried out and the observation are recorded
for the below testing

 Forward rotation
 Reverse rotation
 Constant rotation (jog)
 Alarm

3.6(a) FORWARD ROTATION

The direction of the motor shaft rotates in clock wise direction then it is known as forward
direction.

The below figure shows the flow chart of the forward rotation.

Fig 3.6(a) forward rotation

 Make the connection as per the above flow chart

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 Make the connection from pin 12 and 18 and then connect to the forward switch
 Switch on the power supply
 In drive Set up 5-10(8)
 Press OK button
 Run in forward direction

3.6(b) REVERSE ROTATION

The direction of the motor shaft rotates in anti-clock direction is known as reverse rotation.

The below figure shows the flow chart of the reverse rotation.

Fig 3.5(b) reverse rotation

 Make the connection as per the above flow chart

 make connection for pin 12 and 19 and then connect to the reverse switch
 Switch on the supply
 In drive set up 5-10(8)
 Press OK button
 Run in reverse direction

3.6(c) CONSTANT ROTATION (JOG)

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The motor shaft rotates in same(constant) speed without change in speed is known as constant
rotation (jog), this type of rotation is mainly used in conveyors.

The below figure shows the flow chart of constant rotation

Fig 3.6(c) constant speed

 Make the connection as per the above flow chart

 Switch on the supply
 In drive set up 5-10(14)
 Press ok button
 Run in constant speed(jog)

3.6(d) ALARM TESTING

When the fault occur the drive sense the fault and gives the signal is known as the alarm
signal`

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Fig 3.6(d) Alarm testing

 Remove the any one phase of the motor

 Switch on the supply
 After 30 sec drive sense the fault and gives the alarm signal

3.7.TROUBLESHOOTING OF VLTMICRO DRIVE[3]

Number Description Warning Alar Trip Error Cause of problem

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m lock
2 Live zero error X X Signal on terminal 53 or 60 is less than
50% of the value set in:
 Parameter 6-10 terminal 53 low
voltage
 Parameter 6-12 terminal 53 low
current
 Parameter 6-22 terminal 54 low
current
4 Mains phase loss” X X X Missing phase on supply side, or too high
voltage imbalance check supply voltage.
7 DC over voltage” X X DC link voltage exceeds the limit.
8 DC under voltage” X X DC link voltage drops below the voltage
warning limit.
9 Inverter overloaded X X More than 100% load for too long.
10 Motor thermistor over X X Motor is too hot. The load has exceeded
temperature 100%for too long.
11 Motor ETR over X X Thermistor or thermistor connection is
temperature disconnected.
12 Torque limit X Torque exceeds value set in either
parameter 4-16 torque limit motor made or
4-17 torque limit generator mode.
13 Overcurrent X X X Inverter peak current limit is exceeded.
14 Ground fault X X X Discharge from output phases to ground.
16 Short circuit X X Short circuit in motor or an motor
terminals.
17 Control word time-out X X No communication to frequency converter.
25 Brake resistor short- X X Brake resistor is short-circuited, thus the
circuited brake function is disconnected.
27 Brake chopper short- X X Brake transistor is short-circuited ,thus the
circuited brake function is disconnected.
28 Brake check X Brake resistor is not connected /working.
29 Power board over temp X X X Heat sink cut-out temperature has been
reached.
30 Motor phase u missing X X Motor phase u is missing. check the phase.
31 Motor phase v missing X X Motor phase v is missing. check the phase.
32 Motor phase w missing X X Motor phase w is missing,. Check the
phase.
38 Internal fault X X Contact local Danfoss supplier.
44 Ground fault X X Discharge from output phases to ground
47 Control voltage fault X X 24 V DC is overloaded.
51 AMA check u X Wrong setting for motor voltage and/or

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Unom and Inom motor current.

52 AMA low Inom X Motor current is too low. Check settings.
59 Current limit X X Frequency converter overloaded.
63 Mechanical brake low X Actual motor current has not exceeded the
release brake-current within the start
delay-time window.
80 Frequency converter X All parameter settings are initialized to
initialized to default default settings.
value
84 The connection between X No communication between LCP and
frequency converter and frequency converter.
LCP is lost
85 Key disabled X See parameter group 0-4° LCP
86 Copy fail X An error occurred while copying from
frequency converter to LCP, or from LCP
to frequency converter.
87 LCP data invalid X Occurs when copying from LCP if the
LCP contains erroneous data-or if no data
was uploaded to the LCP.
LCP data not compatible X Occurs when copying from LCP if data are
88 moved between frequency converters with
major difference in software versions.
89 Parameter read only X Occurs when trying to write to a read-only
parameter.
90 Parameter database only X LCP and R-485 connection are trying to
update parameters simultaneously.
91 Parameter value is not X Occurs when trying to write am illegal
valid in this mode value to a parameter.
92 Parameter value X Occur when trying to set a value outside
exceeds the min/max the range.
limits
Nw run Not while Runnin X Parameters can only be changed when the
motor is stopped.
Err. A wrong password was X Occurs when using a wrong password for
entered changing a password-protected parameters

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CHAPTER4

CONCLUSION

VLT micro drive helps to save energy in many application. It is a power conversion device. It
coverts a basic fixed frequency to a variable frequency, variable voltage output. This fixed
output voltage is used to control the speed of induction motors. Primary function of a VLT
micro drive in a aquatic application is to provide energy saving. It enables the motor to run in
forward direction, reverse direction, constant speed(jog).

REFERENCE:-

[1] www.invertekdrives.com

[2] [3]VLT® micro drive manual

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