general intro to drives

Welcome to Danfoss Drives

Confidential / Property of

Danfoss Drives A/S

15 June, 2006

1

Target group: VIP-guests, customers and internal use

Updated: 2006-03-07

Contact: Anette Uldall / Irene Krog Hansen


Danfoss Drives A/S

WelcomeWelcome to Danfoss Drivesto Danfoss Drives


Danfoss Drives A/S

welcomes

NALCO SMELTER TEAM…


Danfoss Drives A/S



Danfoss Drives A/S

15 June, 2006

5

List Of Content

1. Introduction to Danfoss –Global....

2. Danfoss-India...

3. Danfoss Products & solutions....

4.4. Some basic issues related to use of Some basic issues related to use of VFDVFD’’ss……..

5. Various Applications......



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Danfoss headquarters, Denmark



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Danfoss Refrigeration &Air Conditioning

DivisionVagn Helberg

President

Danfoss Motion Controls Division

Sven RuderPresident

Corporate

Functions

Corporate

Ventures

Executive Committee

Danfoss HeatingDivision

Nis StorgaardPresident

Ownershare

38.5%

Danfoss Services

Danfoss Comfort Controls•

Danfoss District Heating•

Danfoss Burner Components•

Danfoss Floor Heating

Danfoss Water Controls

Danfoss Drives•

Danfoss Gearmotors

Danfoss Refrigeration andA/C Controls

•Danfoss Commercial

Compressors•

Danfoss HouseholdCompressors

•Danfoss Industrial & Appliance Controls

Ole Steen AndersenExecutive Vice President, CFO

Hans KirkExecutive Vice President, CDO

Jørgen M. ClausenPresident, CEO

Niels B. ChristiansenExecutive Vice President, COO



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Sales distributed across divisions 2004

2,500

2,000

mill EUR

1,500

1,000

500

00 01 02 03 04

Danfoss Refrigeration & Air Conditioning Division

Danfoss Heating Division

Danfoss Motion Controls Division

Other activities, including Mobile Hydraulics (2000)



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Europe North Latin Africa Asia Pacific TotalAmerica America

Manufacturing sites 39 8 3 1 3 0 54

Sales companies 76 8 7 3 15 2 111

Agents and distributors 107

Danfoss is a family-owned, global company (no public shares, but approx. 1% employee shares)

Net sales 2004: EUR 2,200 mill

Employees: 18,000 worldwide (May 2005)

Production of 250,000 items per day

Group figures



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Group sales

* 1 January 2000 to 3 May

2000

2,500

2,000

1,500

1,000

mill EUR

97 98 99 00 0193 94 95 96 02

Calculated average growth, total: 8.5%

Calculated average growth, Danfoss Group excl. MH: 8.5%

03

Mobile Hydraulics

The Danfoss Group

04

500

1,300

300

1,500

300

1,600

300

1,700

300

1,850150*

1,200

300

1,100

200

900

200

1,8001,900 2,000 2,000 1,900

1,6001,500

1,300

1,100

2,0002,100

2,200



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Ten largest markets 2004

350mill EUR

50

300

150

100

250

200

RA

HE

MC

Germany

Italy

DenmarkGreatBritain

France USA

China

Russia

Spain

Sweden



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Motion Controls Division 2004

4

1

2

3

1

Drives

Silicon Power

Low Power

Gearmotors

3 4

2



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Motion Controls sales split 2004

Drives 81%Incl. Low Power

Silicon Power 3%

Gearmotors 16%



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Danfoss Drives



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Headquarters, Graasten Denmark

History

1968 The first 28 pcs. of VLT® are sold

1983 Acquires Hampton Products in Rockford (now Danfoss Drives, Loves Park)

1989 Centralization of the Danfoss Drives division in the Graasten facility, DK

1995 Graham joins the Drives division

1997 Danfoss Drives be-comes an inde-pendent limited company within the Danfoss Group

1999 Acquires Bauer, Germany.

2000 Establishment of Danfoss Silicon Power, Schleswig, Germany

2001 Acquires IWT Power Electronics GmbH, Kahlsruhe, Germany

2003 Acquires 51% Proexpert, Estonia

2004 Danfoss Drives opensnew factory in Graasten, Denmark



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Danfoss Drives Business Unit

Peter SimsonVice President

Fin, Adm, IT & HR

Charles ManzVice President

Danfoss North America

Morten B. SørensenVice President

Supply Chain

Kim ChristensenVice President

Sales & Service

Finn Jäger-RasmussenVice President

Product Development

Jens Dam MikkelsenVice President

Marketing & SBA

Sven RuderPresident

Danfoss Drives

Hans Peter BoisenDirector

Business Development & Com

Business Boards

Danfoss Drives Ventures



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Facts about Danfoss Drives

• Danfoss Drives is no. 1 in EU and no. 3 worldwide (<160 kW )

• In 1980 we produced approx. 6000 frequency converters, in 2005 weproduced this quantity every 3 days on an average

• Approx. 15-20% yearly growth in frequency converter quantityproduced

• Sales price between 745 and 33,500 EUR per frequency converter

• We produce on customer order, supported by regional assembly in Europe, US and China. This means no inventories of finished goods in the factories

• More than 90% is delivered directly to customers in Europe

• Own printing works: more than 300,000 pages per day

• Total employees Graasten: approx. 1,000

• Total employees Globally: approx. 2,000



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Production in Europe, China and USA

Denmark

Graasten

Germany

Schleswig

USA

Loves Park, IL

Milwaukee, WI

China

Haiyan, Zhejiang Province



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International sales and service

Global network

Local support

24 hours service:

- Spare parts

- Hotline

50 Danfoss sales and service companies

More than 200 partner companies, distributors,

agents and serviceshops



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DANFOSS INDUSTRIES PVT LTD, INDIADANFOSS INDUSTRIES PVT LTD, INDIA

••100% Wholly owned subsidiary of 100% Wholly owned subsidiary of 100% Wholly owned subsidiary of 100% Wholly owned subsidiary of 100% Wholly owned subsidiary of 100% Wholly owned subsidiary of 100% Wholly owned subsidiary of 100% Wholly owned subsidiary of DanfossDanfossDanfossDanfossDanfossDanfossDanfossDanfoss-------- Denmark Denmark Denmark Denmark Denmark Denmark Denmark Denmark

•• Corporate Headquarters : ChennaiCorporate Headquarters : ChennaiCorporate Headquarters : ChennaiCorporate Headquarters : ChennaiCorporate Headquarters : ChennaiCorporate Headquarters : ChennaiCorporate Headquarters : ChennaiCorporate Headquarters : Chennai

•• Factory/Testing Factory/Testing Factory/Testing Factory/Testing Factory/Testing Factory/Testing Factory/Testing Factory/Testing Centre:ChennaiCentre:ChennaiCentre:ChennaiCentre:ChennaiCentre:ChennaiCentre:ChennaiCentre:ChennaiCentre:Chennai........

••Regional /Branch Sales and Service Regional /Branch Sales and Service Regional /Branch Sales and Service Regional /Branch Sales and Service Regional /Branch Sales and Service Regional /Branch Sales and Service Regional /Branch Sales and Service Regional /Branch Sales and Service offices at offices at offices at offices at offices at offices at offices at offices at Delhi,LudhianaDelhi,LudhianaDelhi,LudhianaDelhi,LudhianaDelhi,LudhianaDelhi,LudhianaDelhi,LudhianaDelhi,Ludhiana, Chennai , , Chennai , , Chennai , , Chennai , , Chennai , , Chennai , , Chennai , , Chennai , CoimbatoreCoimbatoreCoimbatoreCoimbatoreCoimbatoreCoimbatoreCoimbatoreCoimbatore, Hyderabad Bangalore , Hyderabad Bangalore , Hyderabad Bangalore , Hyderabad Bangalore , Hyderabad Bangalore , Hyderabad Bangalore , Hyderabad Bangalore , Hyderabad Bangalore Mumbai, Mumbai, Mumbai, Mumbai, Mumbai, Mumbai, Mumbai, Mumbai, AhmedabadAhmedabadAhmedabadAhmedabadAhmedabadAhmedabadAhmedabadAhmedabad, Kolkata. , Kolkata. , Kolkata. , Kolkata. , Kolkata. , Kolkata. , Kolkata. , Kolkata.

•• Distributors and System Distributors and System Distributors and System Distributors and System Distributors and System Distributors and System Distributors and System Distributors and System ––––––––Integrators Integrators Integrators Integrators Integrators Integrators Integrators Integrators spread over the country.spread over the country.spread over the country.spread over the country.spread over the country.spread over the country.spread over the country.spread over the country.



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Drive Testing Centre in Chennai



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Engineered Panel at Danfoss-Chennai Shop floor



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Vision

We will be recognized by our customers as the most respected drives solutions provider world wide

• customer driven

• global

• innovative

• deliver user friendly products

• application focused

• reliable

• quality driven

• ethical

• profitable

• the leader



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Mission

Danfoss Drives offers electronic variable speed drives and related

products and services to the global market. We fulfil our

customers’ needs for drive technology, automation, energy

savings and comfort.

The cornerstones of our unique offering to the market are:

• Unmatched knowledge of our customers’ processes

• The scale advantages resulting from a focused approach

• High performing quality products

• Our global reach



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Goals

• 10% growth a year

• To be number 1 on the worldmarket



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Danfoss Drives guiding strategies

Sales and marketing

• Global reach

• Application know-how

• SBA market and product

approach

Product Development

• Leader in technology and innovation

• Platform based product approach • Integrated product developmentprocess

Supply Chain

• Lean manufacturing

• Mass customization

• One product – one factory

• Integrated manufacturing

People

• Value based people management• Performance based companyculture

• Open communication culture



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One year’s production of advancedpower electronics can save onepower plant a year



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History - products

1968 The first 28 pcs. of VLT® are sold

1983 We become a self-supporting product line

1989 Introduction of VLT® 3000/3000 HVAC series

1992 Introduction of VLT® 3500 HVAC series

1993 Introduction of VLT® 2000 series


1997 Introduction of VLT® DriveMotor FCM 300 series.

1998 Introduction of VLT® 6000 HVAC


2001 Introduction of VLT® 5000 FLUX

2002 Introduction of VLT® 8000 AQUA

2002 Introduction of VLT® Decentral FCD300

2002 Introduction of Decentral Motors Switch DMS

2004 Introduction of VLT® AutomationDrive

VLT® 5, The first VLT

VLT® Decentral FCD 300, year 2002



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VLT® product range

VLT® 2800

0.25 – 18.5 kW

VLT® 5000

0.55 – 1200 kW

VLT® 5000 Flux

0.55 – 400 kW

VLT® 6000 HVAC

0.75 – 500 kW

MCD 3000 Soft Starter

1 – 800 kW

VLT® 8000 Aqua

0.75 – 500 kW



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Decentral solutions

VLT® DriveMotor FCM 300 series

0.55 – 7.5 kW

VLT® Decentral FCD 300

0.37 – 3.0 kW

EtaSolution series K

0.12 – 7.5 kW

VLT® Decentral DMS 300

0.18 – 3.0 kW



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Low Power inverter

Cost-effective motor controllers for OEM customers

Dedicated solutions

Target markets

• Appliance (residential and commercial washing machines)

• Pumps (fresh water, hot water, etc.)



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Silicon Power modules

Standard packagesCustom specific highcurrent Sixpack



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Variable speed solutions

Variable Speed Drive Compressors

BPI: Battery Powered Inverter



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The new VLT® AutomationDrive program

• User-Friendly

• Flexible

• Reliable

• Intelligent



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HVAC & Refrigeration

• Mærsk Container

• York

• Mycom

• Gea Grasso

• Ingersol Rand

• Atlas Copco

Our customers:

• Honeywell

• Johnson

• Trane

• TAC

and many more



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Food & Beverage

Our customers:

• Krones

• Tetra-Pak

• Coca-Cola

• Carlsberg

• Heineken

• Nestlé

and many more



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Water & Wastewater

Our customers:

• Grundfos

• Pentair

• KSB

• ITT

and many more



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Material Handling, Chemical & Textile

Our customers:

• FKI Logistex • BASF • Fong’s

and many more



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Cranes, Lift & Hoist

Our customers:

• Liebherr

• IBA

• Stahl

• DaimlerChrysler• BMW

• Eisenmann

and many more



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Why Use Frequency Converter ?

�Process Optimization

�Control

�Flexibility

�Energy Saving



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Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?

• Avoid Product damageAvoid Product damageAvoid Product damageAvoid Product damage• Reduced Wear & TearReduced Wear & TearReduced Wear & TearReduced Wear & Tear• No Mechanical ResonanceNo Mechanical ResonanceNo Mechanical ResonanceNo Mechanical Resonance• Avoid downtimeAvoid downtimeAvoid downtimeAvoid downtime• Added flexibilityAdded flexibilityAdded flexibilityAdded flexibility• Energy SavingsEnergy SavingsEnergy SavingsEnergy Savings



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Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?Why Use Frequency Converter?

• Reliable Stopping & SynchronizationReliable Stopping & SynchronizationReliable Stopping & SynchronizationReliable Stopping & Synchronization• Reduction in Maximum DemandReduction in Maximum DemandReduction in Maximum DemandReduction in Maximum Demand• Starting Current restricted to 100% Starting Current restricted to 100% Starting Current restricted to 100% Starting Current restricted to 100% ----180%180%180%180%

of full load current.of full load current.of full load current.of full load current.• Improved Power Factor.Improved Power Factor.Improved Power Factor.Improved Power Factor.



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Motion ControlsMotion ControlsMotion ControlsMotion Controls

••95 % of AC Motors have no Controls.95 % of AC Motors have no Controls.95 % of AC Motors have no Controls.95 % of AC Motors have no Controls.95 % of AC Motors have no Controls.95 % of AC Motors have no Controls.95 % of AC Motors have no Controls.95 % of AC Motors have no Controls.

••50% of above are used in Fan and Pumps. 50% of above are used in Fan and Pumps. 50% of above are used in Fan and Pumps. 50% of above are used in Fan and Pumps. 50% of above are used in Fan and Pumps. 50% of above are used in Fan and Pumps. 50% of above are used in Fan and Pumps. 50% of above are used in Fan and Pumps.

••Majority of them are over sized. Majority of them are over sized. Majority of them are over sized. Majority of them are over sized. Majority of them are over sized. Majority of them are over sized. Majority of them are over sized. Majority of them are over sized.

••Typical controls are Dampers and Valves .Typical controls are Dampers and Valves .Typical controls are Dampers and Valves .Typical controls are Dampers and Valves .Typical controls are Dampers and Valves .Typical controls are Dampers and Valves .Typical controls are Dampers and Valves .Typical controls are Dampers and Valves .

••Applications like Compressors, Pumps and Fans use vast amounts Applications like Compressors, Pumps and Fans use vast amounts Applications like Compressors, Pumps and Fans use vast amounts Applications like Compressors, Pumps and Fans use vast amounts Applications like Compressors, Pumps and Fans use vast amounts Applications like Compressors, Pumps and Fans use vast amounts Applications like Compressors, Pumps and Fans use vast amounts Applications like Compressors, Pumps and Fans use vast amounts of of of of of of of of

Energy. Energy. Energy. Energy. Energy. Energy. Energy. Energy.

••An average Motor consumes its own value in Energy in approx. 40An average Motor consumes its own value in Energy in approx. 40An average Motor consumes its own value in Energy in approx. 40An average Motor consumes its own value in Energy in approx. 40An average Motor consumes its own value in Energy in approx. 40An average Motor consumes its own value in Energy in approx. 40An average Motor consumes its own value in Energy in approx. 40An average Motor consumes its own value in Energy in approx. 40 days days days days days days days days

of running. of running. of running. of running. of running. of running. of running. of running.

CONSIDER THISCONSIDER THISCONSIDER THISCONSIDER THISCONSIDER THISCONSIDER THISCONSIDER THISCONSIDER THIS



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.

What is a frequency converter ?What is a frequency converter ?

Control

V & FSpeed

Reference

AC / DC

Rectifier

3-Phase

400V,50Hz

Input Motor

3 phase Output

0-400V,0-50Hz

Fixed AC - DC- Filter DC -Variable AC

DC / AC

Inverter

DC/DC

Filter



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.

What is a frequency converter ?What is a frequency converter ?

Control

V & FSpeed

Reference

AC / DC Rectifier

DC LinkHarmonic

Choke

400V,50Hz

Input

IGBT

Output

Stage

Motor

Output

0-400V,0-50Hz

Fixed AC - DC- Filter DC -Variable AC



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.

What is a frequency converter ?What to specify in a AC VFD ?

Control

V & FSpeed

Reference

EMC/RFI

Filters ?

AC / DC Rectifier(with built in Surge suppressors?)

2 Limb DC LinkHarmonic

chokes?

AC

Input

Supply

IGBT

Standard Motor ?

De rating ?

DC / AC Conversion

Motor Cable Length ?3x 380- 500V+/-10%

wide range?

Long life DC filter

capacitors?No need to

have AC

Line

chokes?

Built in Safety stops standards?

Unlimited o/p switching?

( when output contactor drops?)



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AC DRIVES & MOTORSAC DRIVES & MOTORSAC DRIVES & MOTORSAC DRIVES & MOTORSAC DRIVES & MOTORSAC DRIVES & MOTORSAC DRIVES & MOTORSAC DRIVES & MOTORSSOME BASIC ISSUESSOME BASIC ISSUESSOME BASIC ISSUESSOME BASIC ISSUESSOME BASIC ISSUESSOME BASIC ISSUESSOME BASIC ISSUESSOME BASIC ISSUES

MOTOR EQUIVALENT CIRCUIT



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LOAD TYPESLOAD TYPES

• CONSTANT TORQUE

• VARIABLE TORQUE




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CONSTANT TORQUE LOAD

60%

70%

80%

90%

100%

110%

120%

130%

140%

150%

0% 5% 10%

15%

20%

25%

30%

35%

40%

45%

50%

55%

60%

65%

70%

75%

80%

85%

90%

95%

100%

SPEED

T

O

R

Q

U

E




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VARIABLE TORQUE

0

%

5

0

%

1

0

0

%

1

5

0

%

0% 5% 10% 15% 20%

25%

30%

35%

40% 45%

50% 55% 60%

65%

70%

75%

80%

85%

90% 95%10

0%

SPEED

TO

RQ

UE




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“The True Potential Lies Beneath The Surface”

Below the surface Below the surface Integration approach minimize operating & maintenance costs, optimize savings typically realize ROI within 1-3 years.

On the surfaceOn the surface

VFD is often viewed as a pure capital expenditure item.

However,best cost efficiency is realized when drive is fully integrated into the system.



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• RELIABILITY OF THE DRIVE

• CORROSIVE ENVIRONMENT

• MOTOR-VFD CABLE DISTANCE

• LIFE OF THE DRIVE

• SERVICE SUPPORT

• RESPONSE TIME

• SPARES AVAILABILITY

• USER FRIENDLY KWH MONITORING

SOME BASIC ISSUES RELATED TO USE OF SOME BASIC ISSUES RELATED TO USE OF SOME BASIC ISSUES RELATED TO USE OF SOME BASIC ISSUES RELATED TO USE OF SOME BASIC ISSUES RELATED TO USE OF SOME BASIC ISSUES RELATED TO USE OF SOME BASIC ISSUES RELATED TO USE OF SOME BASIC ISSUES RELATED TO USE OF VFDVFDVFDVFDVFDVFDVFDVFD’’’’’’’’ssssssss



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How critical is the environment

One cannot “see” how critical an environment is.

It essentially depends on 4 factors:

Concentration of pollutants present

Dirt (which becomes conductive in the presence of

moisture)

Relative Humidity

Temperature



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Examples of critical applications

Different constituents attack metals,

• e.g, Sulphur Di-Oxide attacks all metals except Noble metals• Nitrogen, Ammonia and Ammonia Salts attack copper and brass• Hydrogen Sulphide attacks Silver and copper



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How to plan for such installations

Danfoss Drives can support long Motor cables up to 300 meters in length without use of output chokes



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Supply the cabinet with fresh clean air as corrosion process is slow at low humidity and low temperature

It is important to maintain low Humidity and temperature



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IP 66

Protection

OR IP66 Stand alone module upto 90 KW Web_DKDDPB91T102.pdf



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Enclosure

Enclosure

• Side-by-side

mounting

• IP00/chassis

• IP20/chassis

• IP21/NEMA Type 1

• IP55/NEMA Type 12

• IP66



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IP 55 & 66 – stand alone

Enclosure

• Disconnection

switch



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Coated PPCB’s for VLT’s

• For harsh environments e.g. aggressive gasses

• Protects against environmental pollution, moisture and dust

• Confirms to International standards and Marine approval standards



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Ventilation and cooling tips



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Intelligent heat management

Two different cooling modes can take place in ways to offer sets of benefits:

• Conventional cooling

with speed controlled fan

• Air not passing electronic

components

• Cold plate cooling



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FEATURES YOU SHOULD EXPECT

FROM A COST SAVINGCOST SAVING DRIVE

IP 54/66 ENCLOSURE INBUILT TRANSMITTER ISOLATED

NO-NEED OF PANEL POWER SUPPLY I/Os

STANDARD MOTOR AUTO MANUAL INBUILT TRANSMITTERCOMPATIBILITY SWITCH POWER SUPPLY



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FEATURES YOU SHOULD EXPECT

FROM A RELIABLERELIABLE DRIVE

USER FRIENDLY SELF PROTECTING WITH STAND MAINS

FLUCTUATIONS

DIAGNOSTIC SKIP FREQUENCIES FLYING STARTFUNCTIONS



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VECTOR CONTROL AUTOMATIC ENERGY VARIABLE

OPTIMISATION TORQUE

AUTOMATIC MOTOR PID CONTROLLER HARMONIC

ADAPTATION FILTERS

FEATURES YOU SHOULD EXPECT FROM A ENERGY SAVINGENERGY SAVING DRIVE



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TWO (2) SET POINT PIDTWO (2) SET POINT PID

• Ideal for Retrofit with no requirement

of PLC

• Energy Savings are

- Precise

- Process Specific

- Consistent

IN A CLOSED LOOP



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TWO (2) SET POINT PID (Contd)TWO (2) SET POINT PID (Contd)……

• Calculation on 2

feedback signals:

� Minimum

� Maximum

� Sum

� Difference

� Average

• 2 Zone control

with 2 feedback's and 2 set-points

1. Minimum

2. Maximum



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Built-in harmonic filter

Low harmonic emission: THID < 48%

No voltage drop => full output voltage

Built-in DC link filters

Reduces installation cost

Fulfils EN 61000-3-2/3-12

Displacement power factor (cos φ ≈ 1)

True power factor 0.9



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System protection

Protecting the motor

• Thermal monitoring (ETR) / thermistor

• Overload current and torque

Protecting the drive

• Short circuit on motor

• Switching on mains and motors

• Earth fault on motor

• Control I/O short circuit



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Connections

Digital/analogue/

RS 485

Spring loaded

Looping

Thin or thick wires

Pluggable terminals

PC connections

USB 1.1

RS 485



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Plug & Play

Plug & Play connection

to PC via USB

Easy upgrade via plug-

in options

(automatic

configuration)

Modular design makesfor real plug & play operation



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VLT® style design

Smaller footprint

Allocation to same terminal numbers

VLT FC 301 is replacing VLT® 5000

VLT FC 302 is replacing VLT® 5000 Flux

Backwards compatible



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SENSOR POSITIONING THE KEY TO ENERGY SAVINGSSENSOR POSITIONING THE KEY TO ENERGY SAVINGS( for closed loop systems)( for closed loop systems)

System curve:The theoretical squared curve showing the pressure required for any flow

Control curve : The squared curve between the sensor setpoint and the max. operating

point. This curve dictates the actual operating points with variable speed.

Sensor setpoint : The pressure needed to keep the system "primed" for design conditions.



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Energy savings

The area between the control curve and the pump or fan curve graphically represents the savings.

A) Incorrect sensor placement results in linear savings

B) Correct sensor placement results in near cubic savings

A B

SENSOR POSITIONING IMPACT ON ENERGY SAVINGSSENSOR POSITIONING IMPACT ON ENERGY SAVINGS



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PAYBACK !PAYBACK !

AN EXAMPLE AN EXAMPLE



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PAYBACK !PAYBACK !




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PAYBACK !PAYBACK !




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Harmonic distortion by nonlinear loads

Non-linear LoadNon-linear Load

Current DistortionCurrent Distortion Voltage DistortionVoltage DistortionSystem

Impedance

Disturbance to

other users

Disturbance to

other usersContribution to

system losses

Contribution to

system losses

� Current distortion is apparatus level performance

� Voltage distortion is system level performance

HARMONICSHARMONICS



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Harmonic Limitings Standards - Overview

Hong KongrecommendationHK Code of Practice

EuropeStandardEN 61000-3-2

EuropeFuture StandardEN 61000-3-12

UKRecommendationG5/4

NetherlandsRecommendationEnergieNed

North AmericaRecommendationIEEE 519-1992

CountriesTypeName



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1

~

~

~

a

b

c

2 3

64 5

IDC

IDC

Vab Vac Vbc

Ia

Ib

Ic

� Non-sinusoidal currents are drawn from the supply� Pulsating power from the supply source

Harmonic current of a basic 6-pulse rectifier



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Europe: IEC 61000 - 2 -4

USA: IEEE 519 - 1992

Planing level of voltage distortion

10 %5 %3 %THvD

Dedicatedsystem

General systemSpecial/Critical

application

10 %8 %5 %THvD

Class 3Class 2Class 1



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01 2 3 4 5 6 7

-1

-0.5

0

0.5

1

01 2 3 4 5 6 7

-1

-0.5

0

0.5

1

All periodic signals can be

represented as a sum of sine-

functions with periods equal to

integer numbers of the

fundamental component

∑= )sin()( 1thatf h ω

Harmonics is decomposition of a

signal into different (integer of

fundamental) frequencies

Harmonic Analysis



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HARMONIC CURRENT ANALYSIS

---------------------------------------------

Fund. Current38.57 ATHD 104.52%RMS current 55.79 A

5’th Harmonic 30.41 A

7’th Harmonic 23.64 A

11’th Harmonic 10.01 A13’th Harmonic 5.07 A---------------------------------------------

Input Current of a basic rectifier without Input choke

Input current of rectifier with dcInput current of rectifier with dc--link inductorlink inductor

HARMONIC CURRENT ANALYSIS------------------------------------------------Fund. Current36.22 ATHD 42.51%RMS current 39.47 A

5’th Harmonic 12.91 A7’th Harmonic 7.03 A11’th Harmonic 3.06 A13’th Harmonic 2.10 A------------------------------------------------

Input current for rectifier with acInput current for rectifier with ac--side inductorsside inductors

HARMONIC CURRENT ANALYSIS------------------------------------------------Fund. Current36.84 ATHD 43.84%RMS current 40.22 A




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Harmonics ReductionPrice

Performance

Optimum

Solution!

DC Coils

DC+AC No Coils

PassiveFilter

12 Pulse18 Pulse

Active Filter

Active Frontend

Harm. trap

5%

10%

Harmonic Reduction Techniques

Advance Harmonic filters ( AHF)-A Cost effective solution !!!

AlsoAlso-- Harmonic Analysis softwareHarmonic Analysis software--MCT 31 is available MCT 31 is available ––Free!!!Free!!!



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0

200000

400000

600000

800000

1000000

1200000

1yr 2yr 3yr 4yr 5yr

Cost

Rs. save

1 x 30 kW CT Fan VLT6042

Installed cost of Rs.

1,80,000/-

Annual energy savings

of Rs. 2,19,000/-

Payback period : 10 months

Cumulative Cost vs Cumulative Savings

Energy Savings ...



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SOME APPLICATIONS(SOME APPLICATIONS(SOME APPLICATIONS(SOME APPLICATIONS(SOME APPLICATIONS(SOME APPLICATIONS(SOME APPLICATIONS(SOME APPLICATIONS(--------CONTD)CONTD)CONTD)CONTD)CONTD)CONTD)CONTD)CONTD)

ENERGY SAVINGS ON COMPRESSORENERGY SAVINGS ON COMPRESSORENERGY SAVINGS ON COMPRESSORENERGY SAVINGS ON COMPRESSORENERGY SAVINGS ON COMPRESSORENERGY SAVINGS ON COMPRESSORENERGY SAVINGS ON COMPRESSORENERGY SAVINGS ON COMPRESSOREnConEnConEnConEnConEnConEnConEnConEnCon in Compressed Air Systemsin Compressed Air Systemsin Compressed Air Systemsin Compressed Air Systemsin Compressed Air Systemsin Compressed Air Systemsin Compressed Air Systemsin Compressed Air Systems--------BHELBHELBHELBHELBHELBHELBHELBHEL--------MAR05.pptMAR05.pptMAR05.pptMAR05.pptMAR05.pptMAR05.pptMAR05.pptMAR05.ppt


Danfoss Drives A/S

Automotive Components Factory,IKKT,TN

Motor/VFD Rating : 37KW

Details of Compressor : 210 CFM (Retrofit)Date of commissioning : Aug-2003

Unit consumed per hour W/O VLT : 32units (a)

Energy consumed per hour with VLT : 24 units (b)

Energy saved/ hour : 8 unitsCost of energy : Rs.5.00Operation Hours & Days /year : 16*300

Energy saved / Year : Rs.192,000/-


Danfoss Drives A/S

Automotive Components Factory,Chennai

Motor/VFD Rating : 45KW

Details of Compressor : 224 CFM (New comsing)Date of commissioning : Feb-2003

Unit consumed per hour W/O VLT : 37units (a)

Energy consumed per hour with VLT : 28 units (b)

Energy saved/ hour : 9 unitsCost of energy : Rs.5.00Operation Hours & Days /year : 24*300

Energy saved / Year : Rs.324,000/-



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ENERGY SAVING some POTENTIAL Applications

a) Pumps

b) Fans & Blowers

c) Air compressors ( Rotary screw & Recip)

d) Cooling tower ( Fans & Pumps)

e) HVAC system (Various VT Loads)

f) Roots blowers,Aerators etc.,

g) Agitators/Reactors..\Introduction\5_Retrofitting Drives.ppt



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HVAC APPLICATIONS HVAC APPLICATIONS –– Energy saving potentialEnergy saving potential

�Supply Air Fan

�Return Air Fan

�Secondary Pump

�Cooling Tower Fan

�Condenser Pump

�Exhaust Fan

�Fume Hood

�Primary Pump



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Soft Start TypesSoft Start Types

A.C.Switch Type

• SCR - Diode• SCR - SCR

Number Of Phases Controlled

• 1 Phase Control• 2 Phase Control• 3 Phase Control

Control Method

• Open Loop Control• Closed Loop Control



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Single Phase Control

T1

T2

T3

Motor

T1

T2

T3

Motor

Two Phase Control



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Danfoss MCI LH4N2

L1

L2

L3

T1

T2

T3

Motor

Open Loop Control

L1

L2

L3

T1

T2

T3

Motor

Closed Loop Control

..\..\My Documents\Soft Starter Share Folder\MCD 3000\MCD3000 - Product Familiarisation.ppt



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PAYBACK ! PAYBACK !

• Payback varies with

- Application

- Hours of operation

- Cost of energy

- Speed reduction

• Typical payback…

- 1 - 2 yrs on air side

- 1- 2 yrs on water side

- 1-2 yrs for compressor



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User Friendliness

Operational Flexibility

Compliance to Norms

Enhancement of total system efficiency

Upgradability

Safety

Desirable Requirements For Effective Usage



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Points to consider while procurements Points to consider while procurements

of Drives or Soft starters of Drives or Soft starters

� Suppliers Profile/background

� Product Technology

� Application/Process knowledge

� User Friendliness of the product

� After sales support

� Spares Availability even if the

product is obsolete

� AMC support availability

� Faster/Quality service support



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Thanks Thanks



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What is a frequency inverter?

• It is an electronic device that takes a fixed AC supply and converts this into a variable output voltage and frequency to control the speed of a standard induction motor.

• The speed of the motor is dependant on the number of poles in the motor and the supplied frequency.

Motor rpm = Frequency x 60

(no. of pole pairs)

4 pole motor rpm = 50 x 60 = 1500 rpm

2



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.

Control

V & FSpeed

Reference

AC / DC Rectifier

Fixed

380V,

60Hz

Input

IGBT

Output

Stage

Motor

DC

LinkVariable voltage

and frequency

output

What is a frequency inverter?



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How does a frequency inverter produce this

variable voltage and frequency output?

• Most frequency inverters today use a method of “creating” an AC voltage from the fixed DC voltage called PWM (pulse width modulation):

• Output transistors switched on/off at a fast rate (typically ≥4.5KHz) according to a “switching” pattern which creates a series of rectangular pulses of fixed amplitude and varying pulse width

• This pulse width modulation simulates a sinusoidal voltage at the fundamental operating frequency plus harmonic voltages – together they equal the total voltage

• Only the voltage at fundamental frequency (e.g. 0 – 50Hz) creates useful torque

• The harmonic voltage components produce heat in the motor, torque ripple and increased acoustic motor noise



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• The switching on/off of the transistors applies a series of varying width pulses with a magnitude of either +Vdc or –Vdc to the phase outputs (U, V, W)

• The switching pattern which creates the varying width of these pulses has can affect the motor performance

• There are “standard” and “enhanced”switching patterns

• “Enhanced” = better motor performance and compatibility

+Vd

c

-Vdc

PWM switching principle



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• Many frequency inverters use this type of switching pattern

• Also called “sine coded” or “sine weighted” PWM

• Main limitation of Standard PWM is that the maximum output voltage to the motor is limited to 87% of the inverter’s input voltage:

Standard PWM



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.

Motor

V1dc = Vpeak = (Vin x √2)

+V2dc = -V2dc

= (V1dc / 2) = ((Vin x √2) / 2)

Phase-to-Phase

(rms) input

voltage:

Vin = (Vpeak / √2)

Maximum phase to earth peak output voltage = V2dc

Therefore maximum phase to earth rms output

voltage Vpout = (V2dc / √2)

Therefore, maximum phase-to-phase

rms output voltage = (√3 x Vpout))

= (√3 x (V2dc / √2))

= (√3 x ((Vin x √2) / 2) x √2))

= (√3 / 2) x Vin = 0.866 x Vin

Standard PWM – why only 87% mains input voltage

available at output?



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“YES!!”

Does having reduced motor voltage at full speed/full load affect motor performance?

Effect of voltage variation on induction motor characteristics

-20

-15

-10

-5

0

5

10

15

20

-20 -15 -10 -5 0 5 10 15 20

Percent voltage variation

Pe

rce

nt

ch

an

ge

in

mo

tor

pe

rfo

rma

nc

e

Full Load Amps

Power Factor

Efficiency

Starting and Maximum Torque

Starting Amps



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• For a motor operating from a fixed supply frequency (50Hz), to produce motor nameplate rated shaft torque when the mains supply is -10% below motor nameplate rated voltage results in the following:

21% increase in slip to produce rated torque,

2% decrease in efficiency,

9.5% increase in full load amps,

6 - 7°C temperature rise,

for every +10°C. temperature riserise above rated, the lifelife of the motor is reducedreduced 50%50%

Poor motor performance with Standard PWM



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• Switching pattern modulation index can be increased or third harmonic injection can be used to increase output voltage from standard PWM frequency inverters

• Both methods increase fundamental output voltage however but also increase harmonic voltages = limitations

• Theoretically it is possible to achieve a fundamental output voltage 95% of the input voltage however this still means motor operates at best in a 5% under voltage condition

• If try to increase output voltage any further increases harmonicfrequencies in motor = increased motor temperature + torque ripple + acoustic noise = reduced motor performance and efficiency

Can Standard PWM output voltage be improved?



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• In reality what happens if using a standard PWM frequency inverter to control a motor?

• The motor must be derated

It cannot be used for full load output power/torque (e.g. a

15kW motor can only be used for a load which requires

maximum 13kW shaft power)

Due to over-design of systems and selection of standard frame

size motors this might be OK for some applications but this is

a serious limitation of standard PWM – what if you need full

flow, full power, full torque for only 5% of the time?

• Frequency inverter supplier relies on fact that motor has over design built in as part of the motor’s service factor (i.e. lifetime) to compensate for the inverter performance

• This is often true, but is that what a service factor is for?

Standard PWM – the reality !



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• Not all frequency inverters use Standard PWM switching pattern today

• Some frequency inverters have used an enhanced version of PWM (e.g. Danfoss VVCplus) for many years, others are now introducing this

• Enhanced PWM (e.g. VVCplus) = improved performance

Full motor voltageSinusoidal output currentMinimizes motor heating = same motor temp rise as on mains supply Maximizes inverter efficiency

• Many frequency inverters still use Standard PWM and rely on the over design in the system, over sizing of the motor, or result in reduced performance or lifetime of the motor

Enhanced PWM (e.g. VVCplus)



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• Unlike sine weighted PWM, VVC is based on a digital generation of the output voltage.

• Ensures output voltage reaches rated value of input voltage, motor current is sinusoidal and the motor operates as it does on the mains.

Enhanced PWM (e.g. VVCplus)



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• Enhanced PWM (e.g. VVCplus)

Enhanced PWM vs Standard PWM Motor Voltage Difference !

• Standard PWM14%



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• A motor controlled by a frequency inverter using “enhanced”PWM switching technique:

With rated mains supply voltage applied to the drive input,

full rated fundamental output voltage is applied to the motor at rated frequency.

The motor is able to develop its rated power and torque at rated voltage, current, and speed.

The motor operates within its rated temperature rise allowing full thermal life of the motor to be maintained.

Harmonics in the motor are minimized

• The frequency inverter is compatible with the motor

Enhanced PWM (e.g. VVCplus) – Advantages



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• All frequency inverters are non-linear loads resulting in harmonic currents in the mains supply

• Most frequency inverters have one or two basic solutions to reduce harmonics

DC link reactor OR AC input reactor

Other design factors affecting available motor voltage– harmonic filter solutions

1 2 3

64 5

AC-side inductors

~~~

1

~~~

2 3

64 5

DC-side inductor(s)



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• Both DC reactors and AC reactors give similar reduction in harmonics

Other design factors affecting available motor voltage – harmonic filter solutions

HARMONIC CURRENT ANALYSIS------------------------------------------------Fund. Current 36.22 ATHD 42.51%RMS current 39.47 A




• DC reactors





• AC reactors



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• BUT – AC reactors result in a lower DC link voltage and therefore lower voltage available to the motor

• How much lower voltage?

• Example, a 3% AC reactor for an 11kW frequency inverter with a rated current of 25 amps may have an impedance of 1.2mH

• On 60Hz supply this has an impedance XL=2x∏xfxL = 0.45 ohms

• At 25 amps this equates to a voltage drop across reactor of:

V = I x XL = 11.3 volts = 3% of 380V

• Voltage drop across reactor is 90 degrees out of phase with supply voltage so not full 3% drop (Note: DC reactor has no voltage drop)

• But AC chokes also increase diode commutation time

• Typically results reduction in DC link voltage = 0.5 x % inductance

• e.g. 3% AC reactor = 1.5% reduction in DC link voltage,

5% reactor = 2.5% reduction 1 2 3

64 5

AC-side inductors

~~~

Other design factors affecting available motor voltage –

harmonic filter solutions



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• BUT – AC reactors result in a lower DC link voltage and therefore lower voltage available to the motor

• How much lower voltage?

• Example, a 3% AC reactor for an 11kW frequency inverter with a rated current of 25 amps may have an impedance of 1.2mH

• On 60Hz supply this has an impedance XL=2x∏xfxL = 0.45 ohms

• At 25 amps this equates to a voltage drop across reactor of:

V = I x XL = 11.3 volts = 3% of 380V

• Voltage drop across reactor is 90 degrees out of phase with supply voltage so not full 3% drop (Note: DC reactor has no voltage drop)

• But AC chokes also increase diode commutation time

• Typically results reduction in DC link voltage = 0.5 x % inductance

• e.g. 3% AC reactor = 1.5% reduction in DC link voltage, 5% reactor = 2.5% reduction

1 2 3

64 5

AC-side inductors

~~~

Other design factors affecting available motor voltage– harmonic filter solutions

Statement in inverter supplier’s manual



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Standard PWM and AC reactors – the reality !

4 pole 4kW and 5.5kW motor nominal full load torque

0

5

10

15

20

25

30

0 300 600 900 1200 1500 1800

Speed rpm

To

rqu

e N

m

Motor Nominal Torque (4 pole, 4kW) Nm

Motor Nominal Torque (4 pole, 5.5kW) Nm



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Standard PWM

Example of available 4kW and 5.5kW motor shaft torque

0

5

10

15

20

25

30

0 300 600 900 1200 1500 1800

Speed rpm

To

rqu

e N

m



Motor Torque available (4 pole, 5.5kW) with Standard PWM Frequency Inverter Nm (Supplier A)

Motor Torque available (4 pole, 4kW) with Standard PWM Frequency Inverter Nm (Supplier A)

Full torque at full

speed/full load not

available w ith

Standard PWM

frequency inverters -

typically best max

90% FLT available

(especially if AC input

reactors used for

harmonic reduction)



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Standard PWM


0

5

10

15

20

25

30

0 300 600 900 1200 1500 1800

Speed rpm

To

rqu

e N

m





Full torque at full

speed/full load not

available w ith

Standard PWM

frequency inverters -

typically best max

90% FLT available

(especially if AC input

reactors used for

harmonic reduction)



Danfoss Drives A/S

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Standard PWM

Centrifugal Pump or Fan Application

Requirement to oversize frequency inverter and motor

depending on full flow torque requirement

0

5

10

15

20

25

30

0 300 600 900 1200 1500 1800

Speed rpm

To

rqu

e N

m





Centrifugal Pump or Fan load torque Nm

Required full f low

torque not available

w ith standard PWM

therefore need to use

5.5kW frequency

inverter and motor to

give required full f low

torque = increased

cost



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Enhanced PWM and DC reactors – the advantage

Enhanced PWM


0

5

10

15

20

25

30

0 300 600 900 1200 1500 1800

Speed rpm

To

rqu

e N

m



Motor Torque available (4 pole, 4kW) with Enhanced PWM Frequency Inverter Nm (Supplier B)

Motor Torque available (4 pole, 5.5kW) with Enhanced PWM Frequency Inverter Nm (Supplier B)

Full torque at full

speed/full load is

available w ith

Enhanced PWM

frequency inverters

(especially if DC

reactors used for

harmonic reduction)



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124

Enhanced PWM and DC reactors – the advantage

Enhanced PWM

Centrifugal Pump or Fan Application

Same motor as for fixed speed application (4kW)

and 4kW frequency inverter required

0

5

10

15

20

25

30

0 300 600 900 1200 1500 1800

Speed rpm

To

rqu

e N

m


Motor Torque available (4 pole, 4kW) with Enhanced PWM Frequency Inverter Nm (Supplier B)

Centrifugal Pump or Fan load torque Nm

Required full f low

torque is available

w ith enhanced PWM

therefore can use

same 4kW motor as

for fixed speed

application, w ith 4kW

frequency inverter =

low est cost + best

performance



Danfoss Drives A/S

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• By selecting or specifying a frequency inverter which uses an enhanced PWM switching pattern (e.g. VVCplus) and using DC reactors instead of AC input reactors you can be sure the motor will get it’s nameplate rated voltage when operating at full speed, full load and therefore be able to provide full motor shaft torque and power without overloading the motor, or reducing it’s lifetime

• This ensures compatibility with the motor and ensures it operates from the frequency inverter, just as it would if connected to the mains supply

• Inverter duty rated motors, oversized (de-rated) motors are NOT required

• For centrifugal pump and fan HVAC applications – enhanced PWM + DC reactors = standard motors can always be used no matter what the speed/flow range

Motor Compatibility



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• Another important factor to consider is whether the motor’s insulation is compatible with the voltage supply from a frequency inverter

• The voltage supply from a PWM frequency inverter can be very different to the voltage from the mains supply

Motor Insulation – Peak Voltage and Rise Time

• Although not common, this can potentially affect the motor insulation

Voltage Current

Motor Compatibility



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127

• This is generally NOT a problem with “good” quality standard motors and frequency inverters on mains supplies <500V AC

• It can be a problem on higher voltage mains supplies, with “low cost” motors and on special applications – for these special precautions can be taken to prevent problems

• However, for 220V/380V/480V mains supplies, using motors complying with IEC60034-17 and “good” quality frequency inverters, there should be no problems and no need to use inverter rated motors

• Following slides, explain why potentially there can be problems and how to avoid these problems


Motor Compatibility

* Following information comes Danfoss internal studies, studies at Dresden University, Germany and from a study into this topic by GAMBICA (UK drives industry association) and REMA (UK motor manufacturers association)



Danfoss Drives A/S

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• It is a fact that motor winding insulation experiences higher voltage stresses when supplied by a frequency inverter than when connected to sinusoidal AC mains supply

• These higher stresses are dependant on motor cable length and are caused by the interaction of the fast rising voltage pulses of the frequency inverter and transmission line effects in the cable

• To ensure compatibility with a motor, it is necessary to ensure the motor terminal peak voltage (voltage and rise time) are below the levels that the motor insulation is immune to


Motor Compatibility



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• PWM frequency inverters use fast switching IGBTs to create the PWM voltage waveform

• A series of square wave voltage pulses are applied to the motor cable

• The motor draws current and due to the large inductance of the motor this consists of mainly a sinusoidal current waveform at the required frequency of operation


PWM Frequency Inverter – Output Voltage



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• Each pulse of the PWM waveform created by the fast switching IGBTs has a fast rise time (at the output of a typical frequencyinverter this could be approx 100 – 300 ns)

• Rise times are so fast that as it travels along length of the motor cable to the motor it can change the shape of the pulse and may produce voltage overshoot (and change the rise time)

• At the motor, one pulse of the PWM waveform can look very different to the square wave at the frequency inverter output


PWM Frequency Inverter - Motor Terminal Voltage



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• To understand this effect, due to the fast rising pulse, it is necessary to consider the motor cable as a transmission line

• Transmission line effects can then be considered = pulse travelsalong the cable and is reflected at the motor like a wave

• A transmission line consists of a long string of inductor/capacitor sections as shown below (only one phase is considered here):





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• At each fast rising pulse edge the frequency inverter has to charge the inductance and capacitance of the cable so a pulse of energy is delivered into the cable

• Transmission line theory shows pulse travels at velocity

= [1 / √(LC)] m/s

L and C = inductance (Henries) and capacitance (Farads) per metre

• Velocity of a pulse in typical PVC insulated cable

= approx 1.7 x 108 m/s

= in 100ns the pulse travels 17m

• Different cable types give slightly different velocities, but generally the differences are only small

• With this information can study how the fast rising pulse on output of frequency inverter travels along the cable to the motor and how the motor terminal voltage appears as shown 2 slides ago





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• In this theoretical/ideal explanation:

tr = rise time of pulse at frequency inverter output

tp = time taken for pulse to travel length of cable

tr < tp (which is typical for cable lengths >30m)

• Time t = tr• Pulse enters cable at t = 0 and rises to DC link voltage Ud in time tr



• Time t = tr + tp• Pulse travels from inverter to motor

• When reaches motor it is reflected because motor high frequency impedance is > cable impedance

• Reflection causes pulse to rise towards 2 x original peak = 2 x Ud



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• Time t = 2tr + 2tp (i.e. after the pulse has traveled to the motor and back to the inverter)

• Reflected pulse returns to inverter

• Because inverter impedance is low pulse is reflected in a negative sense

• Inverter clamps voltage to Ud resulting in negative pulse as it travels back along cable to motor


• Time t = 2tr + 3tp (i.e. after the pulse has traveled to the motor, back to the inverter and back to the motor)

• Negative pulse is reflected again at the motor and is doubled again = -2 x Ud

• This counteracts the original motor terminal voltage increase




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• In ideal case of previous 2 slides reflections would cause voltage to oscillate continuously

• In the “real world” voltage rise time is increased due to high frequency losses in the cable and waveforms become rounded

• Also due to high frequency losses peak voltage oscillations over one pulse time decay to and stabilise at the DC link voltage (Ud)

• This diagram shows “real world”motor terminal voltage waveform with 42m motor cable





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• Motor peak voltage is therefore a function of cable length and rise time• If the cable length is such that the time for the pulse to travel along

the cable is > the rise time, potentially 2 x Ud peak voltages could occur at the motor

• (Note: Ud is approx the peak voltage of the sinusoidal mains supply at input of the inverter)

• Motor terminal peak voltage will be less with shorter cables (above a certain length – typically >30-50m the peak voltage does not increase)

• Motor terminal peak voltage can be less if the frequency inverter output voltage pulses have a longer rise time for the same motor cable length



Measurements with 460V mains supply



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•When considering the effects of these higher motor terminal peak voltages on the motor insulation, the pulse rise time is important

• IEC 600034-17 and NEMA MG1 Part 30 have different definitions of pulse rise time as shown below

• These diagrams show that with exactly the same waveform, the rise time value can be different by a factor of 2

• Important to understand this if using IEC or NEMA motors





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• Motor terminal peak voltage is an important factor to consider to ensure motor insulation is not damaged

• However, with “good” quality standard motors the peak voltage alone has little effect because the main motor insulation systems between phases and between phases and earth are designed to withstand large over voltages

• However, because of the fast rise time, the peak voltage stresses insulation between turns and especially between randomly touching conductors within a coil or between coil ends


PWM Frequency Inverter - Motor Winding Voltage



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• The pulse voltage travels around motor winding just as it does along the cable

• Diagram shows how this may result in a large % of the pulse voltage appearing between turns, at random points within a coil or between coil ends

• (With a sinusoidal supply the voltage is distributed evenly in the winding)





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• Depending on motor (rating, type of winding, number of turns etc.) and the rise time, the % of the peak terminal voltage appearing between turns or randomly within a coil may reach 30%–90%

• This diagram shows possible variations in 1st coil voltage as a % of the motor terminal peak voltage vs rise time

• With a sinusoidal supply the coil ends only experience a fraction of the phase voltage (determined by number of coils)


• With a PWM frequency inverter it is a combination of the peak motor terminal voltage and the rise time that can cause considerable increase in voltage stress within a coil



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• That’s the bad news …. now the good news !

• “Good” quality motors have adequate insulation systems to prevent damage or reduced lifetime of the insulation when controlled by PWM frequency inverters

• What is a “good” quality motor?

• How do “good” quality motors prevent insulation failure due to these fast rising, high motor terminal peak voltages?


Motor Compatibility



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• There are basically two types of motor winding used for low voltage motors up to 690V


Motor Compatibility

Form wound – often used for higher power motors

Random wound – often used for low power motors



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• Both random wound and form wound motors have similar essential elements in their insulation system

• Phase to earth and phase to phase insulation

In “good” quality motors this is provided by slot liners, slot closures and end winding and will typically consist of polyesterfilm/meta-aramid paperIn low cost, low power motors, this inter-phase “paper”insulation is omitted (PWM frequency inverters should use output LC filters if used with this type of low cost motor)

• Inter-turn insulation

In random wound motors this is provided by multi-layer polyester/polyamide enamel on the conductor

In form wound motors this is provided by mica/polyester wrapped film around the rectangular form wound turns


Motor Compatibility



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• At each fast rising pulse edge the frequency inverter has to charge the inductance and capacitance of the cable

• Depending on the length of cable, the cable charging currents can be high

• For small motors on long cables, the cable charging current can be similar to the motor full load current

• All frequency inverters have a maximum motor cable length based on the rating of it’s internal components (can vary 10m – 300m depending on supplier)

• If frequency inverter not selected correctly can get nuisance tripping with long motor cables – check maximum motor cable length (shielded/screened and unshielded/unscreened)

Other important issues

PWM Frequency Inverter – Maximum Motor Cable Length



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• With the correct selection of frequency inverter it is possible to ensure full compatibility with standard IEC motors without requiring the use of inverter duty motors

• A frequency inverter can provide full protection of the motor but depending on it’s motor current monitoring and fault protection circuits, the reliability of that protection may differ between different suppliers

• Operation of frequency inverters at full load when total mains loss occurs is very short unless a back-up power supply is provided

• Operation of frequency inverters at full load when voltage sags/dips occur according to Semi F47 can vary depending on the frequency inverter design

Frequency Inverters Motor Compatibility, Protectionand Operation on Mains Voltage Sags/Dips

Conclusion



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Highly accurate controls possible

Less or inaccurate systemAccuracy 6

The life of motor increases.

Maximum 1.5 timesThe motor current is 6-7 timesof Rated current

Starting Current5

Trouble free operationMaintenance freeRegular maintenance requiredMaintenance4

Sizes of Motor & associated switchgearreduces

95-98% based operating speed

50-70% based on operating speed

Efficiency3

Better control option0-100%10-85% Speed Variation range

2

Very high efficient & reliable system as no moving parts

Pure Static electronic device

Electromagnetic coupling between Motor & load

Control technology1

SignificanceInverter DriveEddy Current DriveFeaturesSl

Comparison between Eddy Current Drive & Inverter Drive