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LV Drives – Basics & beyond

Presented by Rockwell Automation

What is VFD ? 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.

How Drives Can Can Help How Drives Help  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

Basic Control Classes for AC drives

Basic Volts/Hertz Volts/Hertz Volts/Hertz Control Control (V/Hz) (V/Hz)

Sensorless Vector

Vector Control

Sensorless SensorlessVector Vector Control with Control with slip slipcomp. comp.

Flux FluxVector Vectoror or Field Oriented Field Oriented Control Control w/ out w/ outEncoder Encoder

Flux FluxVector Vectoror or Field Oriented Field Oriented Control Control w/ Encoder w/ EncoderFdbk Fdbk

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) Duty Class

Rated current values for converters& test conditions for assemblies


100% continuous


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


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


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


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


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

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


WHERE CAN ENERGY BE SAVED USING DRIVES ? 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” Saving by Variable Speed 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


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.

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.

Variable Torque Variable Inlet Vane To reduce the flow from 100% to 60% , input power requirements are reduced from

100 %

to 62 %

Saves 38%

ID Fan application

Variable Torque Outlet Damper

ID Fan application

To reduce the flow from 100% to 60% , input power requirements are reduced only from

100 % to

86 %

Saves 14%

Variable Torque

Variable Speed Drive Reduction of flow from 100% to 60% , results into Input power requirements reduction from

100% to 22% Saves 78% of Energy

ID Fan application Energy Saved

Constant Torque


Power α (Speed) Torque is Constant

Some Applications Food processing equipment

Wagon Tippler


Machine tools

Screw Feeder

 Screw Pumps

Conveyor equipment Packaging machinery

Press and stamping  Coal Feeders  Conveyor Crane/Hoists

Wood working machinery


Press and stamping Winder

Compressors Etc…….


Constant Power


Constant Power Zone Example: Blower Spindle


Mixer etc.. NO Energy Saving

Minerals, Mining and Cement,

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

Power Generation

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

Metal and Manufacturing 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

AC Drive and Motor Installation Practices Line Transients

Rockwell Automation Common Mode & Capacitive Coupling Tell me again why I’m using drives?



Reflected Wave

Grounding & Bonding

A little protection and good technique go a long way to insure a good drive installation

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

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


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


Drive System

M Transformer

AC Drive



Drive System

M Transformer

AC Drive


Reflected Waves


Reflected Wave Result


Protect the Motor • 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


Drive System

M Transformer

AC Drive


Line Current Harmonics


Root Cause of Problems with Other Equipment

Current Harmonics create

Voltage 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-onprofiles • 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)


PowerFlex DC

Architecture Class

Component Class


DSI Communication Products







RS-232 DF1








Profibus DP USB Converter





Ext. DSI Kit


Compact I/O

Cable Accessories

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 - Instruction Types include: -- Boolean

-- Process

-- Filter

-- Select / Limit

-- Statistical

-- Timer / Counter

-- Comparison

-- Compute

-- Move

-- PID

– Features: – Positioning Functions – Feedback Options – I/O Slot Options

-- I/O Slot Options -- RoHS Compliant

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

P r e 7.0 s s u r 6.5 e Ksc 6.0

Upper Limit

Average Pr.

Lower Limit - Reqd. Pr.


VFD Advantages In Compressors  No loading / Unloading Cycles  Less Leakages Constant Lower Pressure Process


 Better Motor Efficiency Higher

Power Factor

Controlled Accel / decel Time Lower Lower

Starting Torque Starting Current

 Energy Saving

Perfect Hoist Load Control 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)

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….

Lifting be Liftingapplications applicationscan cannow now besolved solved TM easily featurein inthe the easilyusing usingthe theTorqProve TorqProveTMfeature PowerFlex PowerFlex700. 700.

Can CanHold HoldFull FullLoad Loadin inair airWithout Without Mechanical MechanicalBrakes Brakes?............. ?.............

Auto Energy Saving Feature Auto-Economizer - Extra Saving

“Idle Mode” Energy Saver Reduced Load Automatically fold back Voltage to reduce motor flux

A key in Press like Applications

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

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

Incident at 2:00 AM!!

EtherNet/IP ControlNet

Configuration Flash

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

Readymade PowerFlex Global Objects Key Differences Programming the 1st Drive Competitor’s Drive

~25 minutes

PowerFlex Drive

~3.5 minutes

Key Differences Programming Ten Additional Drives PowerFlex Drive ~7 minutes Competitor’s Drive ~42 minutes

What makes RA Drives More Reliable              

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

Thanks For your Patient Listening Lakhbir Singh Area Manager( East) – Drives Rockwell Automation +91-9874624151


Drive basics  

LV Drive basics & beyond

Drive basics  

LV Drive basics & beyond