LV Drives – Basics & beyond

Rockwell Automation

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What is a VFD

• Diode rectifier converts AC line voltage to fixed voltage DC.

• DC voltage is filtered to reduce current ripple from rectification.

• Inverter changes fixed voltage DC to adjustable PWM AC voltage.

• Diode rectifier converts AC line voltage to fixed voltage DC.

• DC voltage is filtered to reduce current ripple from rectification.

• Inverter changes fixed voltage DC to adjustable PWM AC voltage.

What is VFD ?

� Save substantial energy costs (due to direct speed control)

� Improves Process by smooth speed control

� Save Energy costs by reducing maximum utility demand charges

� Reduce Motor stress & Increase Life of mechanical equipment due to ‘soft starting’ (lower heat, vibration, and transient torques)

� Lower chances of System disruptions (by lowering current inrush from 600% to 100-150%)

� Complete Motor Protection in build

� Automatic Energy Saving Feature

� Substantially brings down – Down time & Maintenance costs

How Drives Can HelpHow Drives Can Help

Basic Control Classes for AC drives

Volts/Hertz

Control

(V/Hz)

Volts/Hertz

Control

(V/Hz)

Sensorless Vector

Control with

slip comp.

Sensorless Vector

Control with

slip comp.

Flux Vector or

Field Oriented

Control

w/ out Encoder

Flux Vector or

Field Oriented

Control

w/ out Encoder

Flux Vector or

Field Oriented

Control

w/ Encoder Fdbk

Flux Vector or

Field Oriented

Control

w/ Encoder Fdbk

Basic Volts/Hertz Sensorless Vector Vector Control

Vector Control vs Flux Vector

Vector Control

– Acknowledges that motor current is the vector sum of the

torque and flux currents and uses this information to provide

better control of motor speed/torque.

Flux Vector Control

– The ability to independently control the flux and torque in a

motor for the purpose of accurate torque and power control.

standard Duty classes IEC-146( converter)

100% continuous, 150% for 2 hours,300 % for 60 sec 6

100% continuous.125% for 2 hours, 200% for 60 sec5

100% continuous.125% for 2 hours, 200% for 10 sec4

100% continuous,150% for 1min in 5 mins3

100% continuous,150% for 1min in 10 mins2

100% continuous 1

Rated current values for converters& test conditions for

assemblies

Duty Class

A,B,C of Sizing & selection

Sizing & selection

� Application ( Types of load ):CT,VT, CHP

� Braking: DC, Resistance, Regeneration

� Communication: Devicenet, control net , Modbus, Ether Net

� Cable Length: Choke, Terminator, Sin Filter

� Feedback: Tacho, Encoder

� Power: As per Duty class

� Temperature: 45 or 50 degree centigrade

�Fans, pumps, blowers etc where the load vary depending upon

the flow rate demanded by process.

�Applications where mechanical methods / eddy current drives

are being used to limit the rated flow.

The most popular applications which result in energy savings are

fans and pumps.

ENERGY CONSERVATION USING VARIABLE SPEED DRIVES

WHERE CAN ENERGY BE SAVED USING DRIVES ?

Application Fan and Pump

Fans, pumps, blowers load vary depending upon the flow rate demand.

•Requirement of application.

•Characteristics of Fan and Pump.

•Principle diagram of Adjusting the flow rate.

•Advantage of Using Drives

“ENERGY” Saving by Variable Speed Drives

PROCESS-Flow Rate, Load Cycle.

FAN SIDE -Torque, Speed & Power.

DRIVES SIDE -Torque, Speed, Current, Power & Motor Details.

FANS & PUMPS -THE CHRACTERISTICS

TORQUE α(Speed)2

POWER CONSUMED α (Speed)3

If speed decreases, the power consumption decreases in a cubic

manner.

THE PARAMETERS INVOLVED :

Drive Advantages

� High motor power factor even at partial load

� Smooth start / stop reduces shock loading on pipelines, reduced torque on motor and peak KVA demand is reduced .

� Efficient fluid flow , better energy management during non-peak demand

� Accurate flow control as per process needs improves product quality (metering, mixing applications)

� Optimum sizing of pumps , low running cost.

� Multiple motor starts and stops are permitted.

� Pipeline leakages are better controlled.

� Throttling Valve, additional piping and friction avoided

� Remote and easy control of Drive and integration with higher level automation is possible.

To reduce the flow from 100%

to 60% , input power

requirements are reduced from

100 % to 62 %

Variable Inlet Vane ID Fan application

Saves 38%

Variable Torque

To reduce the flow from 100%

to 60% , input power

requirements are reduced only

from

100 % to 86 %

Outlet Damper

Saves 14%

ID Fan application

Variable Torque

Reduction of flow from 100% to

60% , results into Input power

requirements reduction from

100% to 22%

Variable Speed Drive

Energy

Saved

Saves 78% of Energy

ID Fan application

Variable Torque

Power α (Speed)

Torque is ConstantP = 2 X Π X N X T

Constant Torque

Food processing equipment

Machine tools

Conveyor equipment

Packaging machinery

Wood working machinery

Press and stamping

Winder

Some Applications

20 % REDUCTION IN SPEED REDUCES 20 % ENERGY CONSUMPTION

Wagon Tippler

Screw Feeder

Press and stamping

Crane/Hoists

Lifts

Compressors

Etc…….

� Crusher

� Screw Pumps

� Coal Feeders

� Conveyor

P = 2 X Π X N X T

Constant Power

P

NO Energy Saving

Example:

Blower

Spindle

Mixer etc..

Constant Power

Zone

Mine cooling fan - AC drive instead of damper

Mine submersible pump - AC drive instead of throttling

Clay workshop ID fan - AC drive instead of damper

Mine ore conveyor - AC cage motor + drive instead of slip-ring motor

Cement factory ID fan - AC drive instead of damper

Minerals, Mining and Cement,

Power plant ID fan - AC drive instead of fluid coupling

Power plant FD fan - AC drive instead of inlet guide vanes

Power plant fans - AC drive instead of inlet guide vanes

Power plant booster fan - AC drive instead of inlet guide vanes

Boiler extract fans - AC drive instead of dampers

Boiler feed pump - AC drive instead of fluid coupling

District heating pump - AC drive instead of throttling

Power Generation

Metal industry ID fans - AC drive instead of damper

Metal industry scrubber pump - AC drive instead of throttling

Steel melting plant fan - AC drive instead of damper

Steel mill roller table - AC drive instead of fixed speed

Wastewater pumping - AC drive instead of on-off control

Water booster pump - AC drive instead of throttling

Water treatment pump - AC drive instead of on-off

Metal and Manufacturing

Rockwell Automation

?

Line Transients

Harmonics

Grounding

&

Bonding

Common Mode&

Capacitive Coupling

Reflected Wave

A little protection

and good

technique

go a long way to

insure a good

drive installation

Tell me again

why I’m using

drives?

AC Drive and Motor Installation Practices

Selection of Motor

� Standard Motor( Insulation level ???) or Inverter Grade Motor

� Forced cooled or self cooled

� Operating Area: safe or hazardous

� Bearing Insulation

Motor Insulation & Choke insulation

24

Design Review Checklist – Line Side

• Distribution System

– Grounding

– Cable type

• Transients and Harmonics

– Converter type

– Line impedance

• Common Mode Noise

– EMI noise

– Cable type

– Cable configuration

25

Design Review Checklist – Load Side

• Reflected wave– Motor insulation

– Cable type

• dV/dt– Motor insulation

– Motor CIV

– Cable charging

• Common Mode Noise– EMI noise

– Bearing currents

– Cable type

– Cable configuration

26

Drive System

Transformer AC Drive Motor

M

27

Drive System

Transformer AC Drive Motor

Reflected Waves

M

Copyrig

Reflected Wave Result

Copyrig

• Output Reactor with and without resistor between drive & motor– Slopes off the waveform (lengthens rise time)

– Reduces destructive force for same amplitude

– Allows longer lead lengths

– With resistor even longer lead lengths

– Reactor does create voltage drop

• Output Filters– dV/dt limiters

• 1204-RWR2, 1204-RWC-17A

• 1204-TFA1, TFB2 “terminator”

– Sine Wave

• Filters

Protect the Motor

30

Transformer AC Drive Motor

Line Current Harmonics

M

Drive System

31

Root Cause of Problems with Other Equipment

Current HarmonicsCurrent HarmonicsCurrent HarmonicsCurrent Harmonics

createcreatecreatecreate

Voltage DistortionVoltage DistortionVoltage DistortionVoltage Distortion

What problems do HARMONICS cause?

• Increased Utility current requirement inability to expand or utilize equipment

• Component overheating distribution transformers & wires

• Nuisance tripping causing lost productivity sensitive equipment

• Equipment malfunction due to multiple or loss of zero crossing

• Noise transfer to other loads possibly even other utility customers

• Incorrect meter readings, relays malfunction maintenance time

• Communication or Telephone Interference problems

• Excitation of Power System Resonance's creating over-voltage’s

• Voltage Flat Topping Problem

How can we reduce the harmonic current?

• DC link choke within the drive

• line reactor

• passive filter

• active filter

• phase shifting loads

• harmonic mitigating transformers

• multi-pulse converters

• active front-end

Guidelines to be taken care during installation of Drive system

• Drives to be installed in clean dry and corrosion free environment

• Keep panel door closed.

• Use suction type vacuum cleaner to clean dust. (No blower)

• Room A.C should have humidity control.

• Use antistatic protection while handling electronic parts. (Self grounding).

• Cable from drive to motor should be 3 core. (Not 3.5 core)

• Never run control or drive input wires in the same conduit as the drive output

wires.

• Keep the distance from the drive to the motor as short as possible to maximize

motor life.

• Never connect incoming supply to drive output terminal.

• Do not conduct insulation test on motor terminal with cables connected to drive

output.

Guidelines to be taken care during installation of Drive system

• Dedicated earth connection from drive P.E terminal to motor P.E terminal is recommended. (No welding using this earth permitted)

• Earth conductor of drive panel, motor, transformer should have at least 50 % cross section of input phase conductor.

• Earth strip of panel should not be used for any other purpose including welding which may lead to electronic component failure.

• All 24V/ 10 V (4-20 mA) control signal cables should be twisted pair screen cables, screen to be grounded at receiving end.

• Do not store the drive more than twelve month without charging. • Set Lower Drive carrier frequency

• Add suppression to all inductive loads (electric brakes, relay coils, solenoids)

Rockwell Offer

PowerFlex Family of Drives

• Power ratings from 0.2kW (0.25 Hp) single phase to 25MW (34,000 Hp) at medium voltage

• Seamless control system integration –maximize uptime

• Decrease development time by as much as 70% with Premier Integration —RSLogix 5000 Software with PowerFlex drives add-on-profiles

• Increase productivity and flexibility with integrated safe speed control technology and safe torque off options

• Flexible control – simplifies operation, reduces training & costs

– Common operator interface & integration capabilities

– Consistent programming structure

– Consistent software tools

– Variety of packaging designs

0.2 kW (0.25 Hp) to 25.4 MW (34,000 Hp)

PowerFlex Family of Low Voltage Drives

PowerFlex drives meet worldwide standards out of-the-box, achieving EMC, global voltage and safety requirements. All PowerFlex

drives offer commonality in networks, operator interface and programming — factors that significantly contribute to ease-of-use and

faster application start-up.

• PowerFlex Component Class AC drives offer you cost-effective motor control for machine-level and stand-alone applications

(PowerFlex 4, 4M, 40, 40P and 400)

• PowerFlex Architecture Class AC drives are designed for advanced application flexibility and control system integration

(PowerFlex 70, 700, 700L, 700H, 755, 700S)

• PowerFlex DC drives are designed for coordinated drive control and drive system applications (PowerFlex DC)

Power

Performance

Component Class

Architecture Class

PowerFlex DC

DSI Communication Products

22-SCM-232

RS-232 DF1

22-COMM-D

DeviceNet

22-COMM-E

EtherNet/IP

22-COMM-P

Profibus DP

22-XCOMM

Ext. DSI Kit

AK-U0-RJ45-*

Cable Accessories

22-COMM-C

ControlNet

22-WIM-Nx

Bluetooth

1769-SM2

Compact I/O

22-COMM-B

BACnet MS/TP

22-COMM-L

LonWorks

1203-USB

USB Converter

PowerFlex 750-Series AC Drives

• The PowerFlex 750-Series of AC drives offers more standard features and selection for control, safety and supporting hardware options than any other drive in its class – Standard embedded Ethernet

– Standard embedded I/O

– Predictive diagnostics

– Real Time Clock

– Safety - Safe Speed and Safe Stop(EN-954)

– DeviceLogix -

– Features:

– Positioning Functions -- I/O Slot Options

– Feedback Options -- RoHS Compliant

– I/O Slot Options

Instruction Types include:

-- Boolean -- Process

-- Filter -- Select / Limit

-- Statistical -- Timer / Counter

-- Comparison -- Compute

-- Move -- PID

PowerFlex755 Drive Awarded

Control Engineering 2010 Engineers’ Choice Award for drives, motion control and motors category

Performance Improvement - Load Sharing

In the world of DRIVES Load Sharing: Involves multiple drives/motors powering the same process

• Each drive contribute a fair share of torque to do work proportional to its own capacity

• When uncoupled roller must not run away - use min torque/speed comparator feature.

• Perfect Speed Synchronization and accurate Torque control

Compressors - Concept - Conventional Control

Time

Upper Limit

Lower Limit - Reqd. Pr.

Average Pr.

Pressure

Ksc

6.5

6.0

7.0

� No loading / Unloading Cycles

� Less Leakages

�Constant Lower Pressure

�Process Feedback

� Better Motor Efficiency�Higher Power Factor

�Controlled Accel / decel Time�Lower Starting Torque�Lower Starting Current

VFD Advantages In Compressors

� Energy Saving

Lifting applications can now be solved

easily using the TorqProveTM feature in the

PowerFlex 700.

Lifting applications can now be solved

easily using the TorqProveTM feature in the

PowerFlex 700.

Benefits include:

– Assured control of the load.

• TorqProveTM assures that the mechanical brake has control of the load when stopping the drive, and the drive has control of the load when releasing the brake during a move command

• TorqProveTM and Force TechnologyTM helps eliminate concerns with brake timing and environment changes inherent in V/Hz drives

– Reduced set-up time

• Very easy to set-up – only a few parameters

• No PLC programming required for function (brake control is performed by drive)

Perfect Hoist Load Control

Can Hold Full Load in air Without

Mechanical Brakes ?.............

Can Hold Full Load in air Without

Mechanical Brakes ?.............

References :

Bhutan Ferro Alloys Ltd on Hot Metal Bucket

BALCO Korba for Bucket Pick and drop

Bhushan Steel Orissa

LMW Foundary Shop

Hindustan Zinc etc….

Confidential -- For Internal Use Only. Copyright © 2008 Rockwell Automation, Inc. All rights reserved.

Auto-Economizer - Extra Saving

“Idle Mode” Energy Saver

Reduced Load

Automatically fold back Voltage to reduce motor flux

Auto Energy Saving Feature

A key in Press like Applications

Performance Improvement - Premier Integration with Powerflex Drives

Controller-based Automatic Device Configuration (ADC)

Controller will automatically detect a node replacement, flash it if necessary, and download the configuration settings

EtherNet/IP

ControlNetFlashConfiguration

Incident at 2:00 AM!!

Benefits Using RA Drive with RA Controllers – Pre.Intg.

• Reduce drive system development time by as much as 70%*:

– Use one software tool to configure the entire Logix / drive system

– Controller and drive network connections are configured at the same time

• eliminates I/O mismatch errors

– Auto-generation of descriptive tag names

– Auto-generation of respective tag data types

– All drive configurations are saved in the RSLogix

project file and in the Logix controller

Competitor’s Drive PowerFlex Drive~25 minutes ~3.5 minutes

Key Differences Programming the 1st Drive

Readymade PowerFlex Global Objects

Key Differences Programming Ten Additional Drives

Competitor’s Drive ~42 minutes PowerFlex Drive ~7 minutes

� Ambient Temperature of 50 Degree C.

� Flexible performance with ForceTM Like Technology.

� Seamless Integration

� Built in DC Chokes to abate input Current Harmonics (Obeys IEEE 519 -1992 Standards) with 97.5% Efficiency

� Power Devices having PIV of 1700V and Transient Protection of 6KV

� Built in Software to control the effect of reflected wave

� Built in EMC Filters and common mode core to address noise related issues. Conformity to EMC directives and european Standards.

� Excellent Feature of Zero Stacking

� PTC input to the Drive

� Internal family of communications and HIM modules

� 7th IGBT – Chopper is internally Provided

� Over Load Capacity as per Application.

� Complete Output Short Circuit Protection

� Compact Size

What makes RA Drives More Reliable

50

Thanks For your Patient Listening

Lakhbir Singh

Area Manager( East) – Drives

Rockwell Automation

+91-9874624151