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I.E.E.E. Industry Applications SocietySeminar on 3 Phase Motor Starting -- 2004.02.21

I.E.E.E. -- I.A.S.Motor Starting Seminar

By: James S. Nasby, Director of EngineeringMaster Contr ol Systems, Inc. (mastercontrols.com)

Seminar Details & Background

Background (History of Seminar)National Fir e Pr otection Association (NFPA)

Pumps for Fire Protection Systems

NEMA Standar d MG-1Motors and Generator s

See Also: Section VIII .References Cited

Topics to be Covered

I. Induction Motors General

II. Electrical Power Supply

III. Induction Motor Parameters

IV. 3 Motor Starting Types (8+ 1)

V. 3 Motor Running Types (3)

VI. Common Motor Wiring Types (14)

VII. Installation Considerations

VIII. References Cited

I. Motors GeneralMotor Types

Induction Motors

Three Phase

Non-Salient Pole Motors:

Usually Squirrel Cage Rotor Motors -but-

can be Wound Rotor (Slip Ring)

Induction Motors

Usually Squirr el Cage

Design Type: Usually NEMA Design BNormal Starting Torque

Normal Starting Current (KVA) Synchronous Motors Not Covered

I. Induction MotorsGeneral Definitions

Motor Poles Even Numbers (2, 4, 6, etc.)

Synchronous Speed (No Load Speed - Slip)

Starting Region Fixed Impedance

Running Region Energy Converter

Torques:Stall = Locked = Zero Speed Torque

Pull-up Torqu e

Breakdown Torque

Rated Torque

Starting Amps, KVA & Locked Rotor Code

Motor Starting Region contdMotor Torque Curve

Motor Torque and Pump Torque Curves

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II. Electr ical Power SuppliesPower Sources - Mains

Types of Power Source Three Phase A.C.

Power Source Characteristics

(Parameters)

Voltage (Utilization Voltage) -at-

Low voltage or Medium Voltage

Frequency 50 Hz or 60 Hz

Starting Voltage Drop -vs- Starter

Runn ing Voltage Drop -vs- Motor

Power Supply Characteristics contd- Power Quality -

Source Capacity - Weak or Stiff Source Starting Voltage Drop (15% of Controller Rated) Running Voltage Drop (5% of Motor Ra ted)

Method of Calculating - NEMA ICS-14

Gen-Sets - Frequency & Voltage

Voltage Balance (Amount of Imbalance)Small Voltage "Unbalnace" = Lar ge CurrentImbalance. (See NEMA MG-1, par t 1-14.36)

Voltage Har monics (Heats Windings)

Power Factors - Affected by Motor

III. Induction Motor Parameters

General Motor Cha racteristics

Induction Motor Types

Wound Rotor Motor

(Slip Ring Motor )

= Rotary Transformer

Squirr el Cage Motor = Ditto

But with Slip Rings Shorted

Frequency 50 Hz -vs- 60 Hz

NEMA Design Type B (MG-1)

NEMA Design Types

StandardThree Phase

InductionMotors are

NEMADesign B

( Rated Full Load Torque)

Rated || Speed (RPM)

Induction Motors - contdMotor Parameters - Electrical

Locked Rotor Code (KVA per Hp)

Service Factors

Usually 1.15 Maximum Allowed

Often Higher for Smaller Motors

Usually 1.0 Max. when used with VFD's

Service Factor (S.F.) -vs- Ideal Conditions

Max. Temperatur e (40 C Max.) -and-

Max. Altitude (3,300 ft /1,000 m Max.) -and-

Max. Voltage Imbalance (1% Max.)

Motor Parameters contdAbbreviations & Acronyms

Motor Currents FLA = Motor Full Load Amperes

FLC = Motor Full Load Current = FLA

LRC = LRA = Locked Rotor Current (Amps)

SFA = Service Factor Amps

Locked Rotor Code* Codes F & G Common

*May be Much Higher for Smaller Motors

and for Energy Efficient Motors

Power Factor (PF) Real -vs- ImaginaryStarting PF = 30% / 40% Typically

Running PF = 80% down to 8.0% from

Full Load to No Load, Typically

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Motor Parameters contdMotor Current Curve

Motor Current -vs- RPM Curves

Rated Running Current = 100%

Induction Motor Locked Rotor Codes

Table M-02 -- Motor Locked Rotor Code KVA Data and Allowed Horsepowers

"F" "G" "H" "J"Code Letter

Min. Max. Min. Max. Min. Max. Min. Max.

KVA per Hp 5.00 5.59 5.60 6.29 6.30 7.09 7.10 7.99LRA/FLA 482% 540% 540% 608% 608% 685% 685% 772%Allowed Hp 15 Hp and up 15 Hp and up 5 thru 10 Hp 5 Hp only

Note: The LRA/FLA ratios shown are approximate for illustration only.

Table M-03 -- Maximum Motor Locked Rotor Currents

Motor Voltage - 60 Hz valuesRated

HorsepowerCode

Letters 200 Vac 208 Vac 230 Vac 460 Vac 575 Vac

5 F - J 106 102 92 46 377.5 F - H 147 142 128 64 5110 F - H 186 179 162 81 6515 F - G 267 257 232 116 9320 F - G 334 321 290 145 11625 F - G 421 405 366 183 14630 F - G 499 480 434 217 17440 F - G 667 641 580 290 23250 F - G 833 801 724 362 29060 F - G 1,001 962 870 435 34875 F - G 1,249 1,201 1,086 543 434

100 F - G 1,668 1,603 1,450 725 580125 F - G 2,088 2,008 1,816 908 726150 F - G 2,496 2,400 2,170 1,085 868200 F - G 3,335 3,207 2,900 1,450 1,160250 F - G 4,198 4,036 3,650 1,825 1,460300 F - G 5,060 4,865 4,400 2,200 1,760350 F - G 5,865 5,639 5,100 2,550 2,040400 F - G 6,670 6,413 5,800 2,900 2,320450 F - G 7,475 7,188 6,500 3,250 2,600500 F - G 8,338 8,017 7,250 3,625 2,900

Note: The 460 Vac LRA values are from NFPA 20 Table 6-5.1.1. Others are calculated usingvoltage proportion.

Induction Motor Locked Rotor CurrentsMotor Parameters contd

Motor Stalled (Locked Rotor)Power Factor = Approx 40%

Motor Parameters contdMotor Theory and Formulae

Pur pose Electrical to Mechanical

Ener gy Conversion

Motor Star ting Region (Rotary Solenoid)

Running Region (Ener gy Converter )

Motor Torque & Motor Current Draw

-vs- Speed Curves

A-T-L-Starting

(Basic Motor Char acteristics)

Power Factor & Phase Angles

Efficiencies

Motor Starting -vs-Motor Running Regions

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Motor Starting -vs-Motor Running Regions

MotoringRegionStarting Region

Motor Parameters contdMotor Torque Curve


Motor Parameters contdMotor Torque Curve



Motor Curr ent -vs- RPM Curves



Motor Current -vs- RPM Curves


MotoringRegionStarting Region

Motor Theory and FormulaeMotor Starting Region

For a Motor at Stall, Motor Impedance isConstant. So:

I = E / Z (Ohms Law)

Current is Directly Proportional toMotor Voltage. I.E.:

Motor Current = Voltage / Impedance

Power Factor (P.F.) is Typically 30% to40% at Stall (and for most of thestarting region)

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Motor Theory and FormulaeMotor Star ting Region contd

In the Starting (Accelerating) Region:Torque is Proportional to the Square of

the Applied Motor Voltage

T = K1 x V2 -or- Since Current isproportional to Voltage (see above):

T = K2 x I2

Thus: Torque is also Proportional to theSquare of the Motor Current

Motor Theory and FormulaeMotor Star ting Region contd

Example of Starting Torque Proportional tothe Square of Applied Motor Voltage.

E.G. 57% Volts = 33% Rated Stall Torque.

Motor Theory and FormulaeMotor Running Region

Motor Running Region (Energy Converter):

Mechanical Power is Torque x Speed:

Pm = K3 x Tq x RPM

Motor Torque is Whatever the Load Requires

Electrical Power Input is:

Pe = Pm + Motor Losses = Pm / Efficiency

But, Electrical Power Input is also given as:

Pe = K4 x V x Ireal (Volts x Real Current)

So: Ireal = K5 x Pe / Volts

Thus Motor Current is Inversely Proportionalto Motor Voltage with a Running Motor

Motor Running -vs-Motor Starting Regions

Rated Torque (100%) times Rated Speed (E.g.1750 RPM) yields Motor Rated Hor sepower.

IV. Motor Starting

General - Overview Types of Reduction

Voltage Reduction: WyeDelta, Soft Start, a ndAutotransformer

Curr ent Reduction: Primar y Impedance (Primar yResistor, Primary or Neutral Reactor)

Motor Impedance (Wound Rotor)

Two Specialty Types

Medium Voltage Four C ommon Types: A-T-L,Primary Reactor, Neutral Reactor -and-Autotransformer

Low Voltage - Wound Rotor (Not U.L. Listed)

Motor Starting - contdEight (+1) Common Low Voltage Starting Types:

Across-the-Line (A-T-L or Direct-On-Line)

Part Winding (Half Winding) Start

Primary Resistor Start

Primary (or Neutral) Reactor Start

Wye-Delta (Star-Delta) - Open Transition

Wye-Delta (Star-Delta) - Closed Transition

Soft Start / Soft Stop (SCR Phase Modulation)

Autotransformer

VFD Ramp-up (and Ramp-down on some)

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Motor Starting contdAcross-the-Line (Direct On Line)

Motor Starting contdAcross-the-Line (Direct On Line)

Motor Starting contdPart Winding Start

Note: The Motor Must be WoundSpecifically for Part Winding Starting.

Motor Starting contdPart Winding Start

Motor Starting contdPrimary Resistor Start

Motor Starting contdPrimary Resistor Start

Note: 65% Resistor Impedance is

1.24 -0.40 = 0.84 pu

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Motor Starting contdPrimary Reactor Start

Motor Starting contdPrimary (or Neutral) Reactor Start

Note: 65% Reactor Impedance is

1.54 1.00 = 0.54 pu

Motor Starting Torque Comparison

Curves B, C & D are at 65% Motor Starting Voltage(Reference Source Credit on Next Slide)

00

Motor Torque Comparison contdA=ATL, B=A.T., C=Pri. Res., D=Reactor

Gerhart W. Heumann (G.E.), MagneticControls of Industrial Motors, Wiley & Sons.

Motor Starting contdPrimary (or Neutral) Reactor Start

Motor Starting contdWye-Delta Open Transition

LPM Module = Leading Phase Monitor

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Motor Starting contdWye-Delta Transition Hazard

Closed

Leading

Lagging

Motor Starting contdWye-Delta Closed Transition

Motor Starting contdWye-Delta (Open or Closed Xtn.)

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Motor Starting - contdSoft (Solid State - SCR) Start

Motor Starting - contdSoft (Solid State - SCR) Start

Motor Starting - contdAutotransformer Start

Motor Starting - contdAutotransformer Start

Motor Starting CharacteristicsParameter Chart

Fire Pump Starting Type Characteristics- for -

Electric Fire Pump Motors and Controllers

Starting Chara cteristics (at Stall) -- Typical Values -for- Fully Load Pump (1)

Starting Starting Starting AccelerateMotor Motor Amps Amps Starting Power Starting Full LoadType Contactors Closed & KVA & KVA Power % F.L. Torque to

Starting Type Note Note (3) Transition % LRA % FLA Factor Note (4) % ATL Full Speed Notes

Across-the-Line Any 1 N/A 100% 600% 40% 240% 100% Yes (a)

Part Winding Special (2) 2 Yes 65 390 40 156 48 Usually (b)Primar y Resistor Any 2 Yes 65 390 80 314 42 Yes (c)

Primar y Reactor Any 2 Yes 65 390 28 111 42 Yes (c)

Neutral Reactor 6/12 Lead 2 Yes 65 390 28 111 42 Yes (c)

Wye-Delta Open 6/12 Lead 3 No 33/100 200/600 40 80/240 33 No (d)Wye-Delta Closed 6/12 Lead 4 Yes 33/100 200/600 40 80/240 33 No (d)(e)

Soft Start/Stop Any 1/2 Yes 40/67 240/400 Varies Ramps 16/44 Yes (f)

Autotransformer Any 3 Yes 46 276 40 110 42 Yes (c)(g)

Motor Starting CharacteristicsParameter Notes to Chart

Motor Starting Characteristics Chart

Notes(1) Refer to Factory details.

(2) Part Winding Motors must be wound specifically for this service. Some motors may notaccelerate to full speed in the starting mode. See Note (b).

(3) Units with two or more contactors have two basic steps (Accelerate & Run) with steps threeand four being for transitions.

(4) Starting KW Power as a percent of motor full load power requirement.

(a) Also called "A-T-L" or Direct-On-Line. Motor Power Factor taken as 40%. Other values

shown are due to the effects of the controller.(b) Part Winding Parameters vary with the motor. Starting Amps & KVA vary from around

60% to 70%, Starting Torque from around 45% to 50%. The motor can start a fully loadedpump if it has no large torque dip or cusp. See the text discussion on Part Winding Startingfor details.

(c) Figures are for tap set at 65% which yields a motor voltage of 65% of line (mains) voltage.(d) The Dual Figures are for Starting and Transition. The transition values are to finish

accelerating a fully loaded pump. Examples include deluge or open systems, re-starting afully loaded pump after a power failure or interruption, and failure of another pump feeding

the same system.(e) Ignores the momentary transition resistor loads.

(f) Varies with pump load and particular Soft Starter used. Values shown are initial andmaximum for a typical fully loaded pump. MCS uses the second (Start) contactor for

isolation. Others use only the Bypass contactor.(g) The 46% Starting Amps & KVA figures include the Autotransformer exciting current.

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V. Motor Running Types

Constant Speed Running Full Voltage Running

- Synchronous Speeds (3,600 RPM & etc.)

- Slip Frequencies - Running (Rated) Speeds

Motor Lead Wire Running Currents

- Three Lead = Full Motor Current

- Six Lead Parallel Run (Part Winding Start)

= 50% of FLC per set

- Six Lead (Wye-Delta Start)

= 58% (57.7%) of FLC per set

Motor Running - contd

Variable Speed Running Wound Rotor Control

- Changes Motor Secondary Impedance -and-

- Motor Torque Curve

Variable Frequency - Variable SpeedContr ol (VFDs)

- Changes Motor Torque and Current Curves

- Changes Motor Synchronous Speed and-

- Changes Motor Running (Loaded) Speed

Wound Rotor Speed-Torque Curves(Reference Source Credit on Next Slide)

Wound Rotor Speed-Torque Curves- Flipped and Rotated -

Gerhart W. Heumann (G.E.), MagneticControls of Industrial Motors, Wiley & Sons.

VI. Motor Wiring Motor LeadConfigurat ions (Fourteen)

Three Lead Three Coil

(Single Voltage) (T1-T3)

Six Lead Thr ee Coil

Wye Runing (T1-T3 & T4-T6) Delta Running (T1-T3 & T4-T6)

Par allel Run (Six Lead - Six Coil)

T1-T3 and T7-T8 - or -

Both Sets Labeled T1-T3

Motor Lead Configurations3 Lead 3 Coil - Wye Running

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Motor Lead Configurat ions3 Lead 3 Coil - Delta Running

Motor Lead Configurations6 Lead - 3 Coil - Wye Running

Motor Lead Configurat ions6 Lead 3 Coil - Delta Running

6 Lead 6 Coil - Wye RunningParallel Running

6 Lead - 6Coil - Delta RunningParallel Running Motor Wir ing contd

Nine Lead (Dual Voltage) (T1-T9)

Wye Wound

Delta Wound

Suitable for Par t Winding Start ?

Twelve Lead (T1-T12)

Dual Voltage

Single Voltage (Para llel Run )

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9 Lead - 6 Coil - Wye RunningSeries Running

9 Lead - 6 Coil - Wye RunningParallel Running

9 Lead - 6 Coil - Delta RunningSeries Running

9 Lead - 6 Coil - Delta RunningParallel Running

12 Lead - 6 Coil - Wye RunningSeries Running

12 Lead - 6 Coil - Wye RunningParallel Running

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12 Lead - 6 Coil - Delta RunningSeries Running

12 Lead - 6 Coil - Delta RunningParallel Running

Typical 12 Lead Motor Wiring Diagram

Courtesy of Marathon Electric

VII. Induction Motors --Installation Considerations

Physical

Location - Ideally Within Site of Controller

Motor Protection: Fire, Security, Other Hazards

Access All Sides & Condu it Access

Electrical N.E.C. (NFPA 70) - 430 (& 695)

Conduit & Hubs

Environmental

Conductor Sizing Incoming & Motor Cir cuit

Voltage Drops: Start & R un

Cable Impedances and Run Lengths(See NEMA ICS-14)

Motor Installation contdStart-up (Commissioning)

Current Measurements

Voltage Measurements

Estimating Motor Load

- FLA -vs- Voltage

- SFA (115%) - Max. AllowedUnder Any Conditions(Temperature, Altitude, VoltageImbalance) on ANY Phase

Starting Methods -vs- Motor Types

Table M-04 - Mot or and Start ing Types

Starting Type Motor Type Starting Type Motor Type

Full voltage Standard/Any Primary Reactor Standard/Any

Part Winding Part Winding Primary Resistor Standard/Any

Wye Delta - Closed Delta Run Autotransformer Standard/Any

Wye Delta - Open Delta Run Soft Start (SCR) Standard/Any

Neutral Reactor Wye Running Wound Rotor Wound rotor

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Motor Types -vs- Starting Types

Motor Description(a)

Starting Method(b)

Run Type Number of Leads PartWinding

Wye (Star)Delta

(c)

NeutralReactor

"Other 5" Figure

W ye R un T hr ee L ea d N o N o N o Y es 7- 4

Delta Run Three Lead No No No Yes 7-5

Wye Run Six Lead, Single Coil No No Yes Yes 7-6

Delta Run Six Lead, Single Coil No Yes No Yes 7-7

Wye Run Six Lead Parallel Some(d)

No No Yes 7-8

D el ta Run S ix Lead P ar al lel S om e(d)

No No Yes 7-9

Wye Run Nine Lead Ser ies No No Ye s Ye s 7-10

Wye Run Nine Lead Parallel Some(d) No No Yes 7-11

De lt a R un N ine L ea d Ser ie s N o N o N o Ye s 7- 12

D el ta Run N in e Lead P ar al lel N o(e)

No No Yes 7-13

Wye Run Twelve Lead Seri es No No Ye s Ye s 7-14

Wye Run Twelve Lead Parallel Some(d) No Yes Yes 7-15

De lt a R un T we lve L ea d Se ri es N o Y es N o Ye s 7- 16

Delta Run Twelve Lead Parallel Some(d)

Yes No Yes 7-17

Notes:(a) The Motor "Type" (Wye or Delta) is theRunning configuration, regardless of how the motor is started.

Wound Rotor Motors are not covered in this chart.(b) "Other 5" are: Full voltage (A-T-L), Primary Resistor, Primary Reactor, Soft Start and Autotransformer.(c) Either Open or Closed Transition Wye-Delta (Star-Delta).(d) "Some" = May be usedonly of the motor is labeled as suitable for Part Winding Starting.(e) The 9 lead "Double Delta" method has unequal currents and is not suitable for standard Part Winding controllers.

Table M-06 -- Motor SuitabilityMotor Types -vs-Starting Types VIII. References Cited

A. National Fire Protection Association (NFPA)

Kenneth I. I sman, Milosh T. Puchovsky,

"Pump for Fire Protection Systems"

B. NEMA Standard MG-1,

"Motors and Generators"

C. NEMA ICS-14,

"Application Guide for Fire PumpControllers"

D. Institute of Electrical and Electronic Engineers(I.E.E.E.) numerous papers on motors.

Pumps for Fire Protection Systems-by- Ken Isman & Milosh Puchovsky

- with -

Chapters on

- PowerSources

- Motors,

- and -

- Controllers

by Jim Nasby

NEMA Standard MG-1Motors and Generators

NEMA ICS-14Fire Pump Controller Application Guide Thank You !!

The Chicago Chgapter of the I.E.E.E.

Industrial Applications Society

-- and from --

Jim Nasby, Mastercontrols.com

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