This document discusses motor parameters and starting types for three-phase induction motors. It covers topics such as motor types, electrical power supplies, motor parameters, starting torque curves, and eight common starting types including across-the-line, part-winding, primary resistor, primary reactor, wye-delta open and closed transition, soft start, and autotransformer starting. Tables provide motor locked rotor codes, currents, and allowable horsepowers. Diagrams illustrate motor torque and current curves as well as the operation of various starting methods.

1. Factory Mutual Approvals
Motor Parameters & Starting
By: James S. Nasby -- Columbia Engineering

2. Seminar Details & Background
♦ Background (History of Seminar)
National Fire Protection Association (NFPA)
“Pumps for Fire Protection Systems”
♦ NEMA Standard MG-1
Motors and Generators
♦ See Also: Section VIII.
References Cited

3. Topics to be Covered
I. Induction Motors – General
II. Electrical Power Supply
III. Induction Motor Parameters
IV. 3Ø Motor Starting Types (8+1)
V. 3Ø Motor Running Types (3)
VI. Common Motor Wiring Types (14)
VII. Installation Considerations

4. I. Motors – General
Motor Types
♦ Induction Motors
♦ Three Phase
♦ Non-Salient Pole Motors:
Usually Squirrel Cage Rotor Motors -but-
can be Wound Rotor (Slip Ring)
Induction Motors
♦ Usually Squirrel Cage
♦ Design Type: Usually NEMA Design “B”
Normal Starting Torque
Normal Starting Current (KVA)
♦ Synchronous Motors Not Covered

5. I. Induction Motors
General 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 Torque
Breakdown Torque
Rated Torque
♦ Starting Amps, KVA & Locked Rotor Code

6. Motor Starting Region –
cont’d
Motor Torque Curve
Motor Torque and Pump Torque Curves

7. II. Electrical Power Supplies
Power 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
– Running Voltage Drop -vs- Motor

8. Power Supply Characteristics – cont’d
- Power Quality -
♦ Source Capacity - Weak or Stiff Source
– Starting Voltage Drop (15% of Controller Rated)
– Running Voltage Drop (5% of Motor Rated)
– Method of Calculating - NEMA ICS-14
– Gen-Sets - Frequency & Voltage
♦ Voltage Balance (Amount of Imbalance)
Small Voltage "Unbalance" = Large Current
Imbalance. (See NEMA MG-1, part 1-14.36)
♦ Voltage Harmonics (Heats Windings)
♦ Power Factors - Affected by Motor

9. III. Induction Motor Parameters
General Motor Characteristics
♦ Induction Motor Types
– Wound Rotor Motor
(Slip Ring Motor)
= Rotary Transformer
– Squirrel Cage Motor = Ditto
– But with Slip Rings Shorted
♦ Frequency – 50 Hz -vs- 60 Hz
♦ NEMA Design Type “B” (MG-1)

10. NEMA Design Types
Standard
Three Phase
Induction
Motors are
NEMA
Design “B”
( Rated Full Load Torque)
Rated | Speed (RPM)

11. Induction Motors - cont’d
Motor 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. Temperature (40 °C Max.) -and-
– Max. Altitude (3,300 ft /1,000 m Max.) -and-
– Max. Voltage Imbalance (1% Max.)

12. Motor Parameters – cont’d
Abbreviations & 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- Imaginary
Starting PF = 30% / 40% Typically
Running PF = 85% down to 8.0% from
Full Load to No Load, Typically

13. Motor Parameters – cont’d
Motor Current Curve
Motor Current -vs- RPM Curves
Rated Running Current = 100%

14. Induction Motor
Locked Rotor Codes
Maximum Allowed Motor Locked Rotor Codes
per NFPA-20:
♦ Code "F" for 15 Hp & up -or-
5.0 thru 5.59 KVA/Hp = approx. 540% FLA
♦ Code "G" for for 15 Hp & up
5.6 thru 6.3 KVA/Hp = approx. 600% FLA
♦ Code "H" for 5 thru 10 Hp
(up to 7.1 KVA/Hp = approx. 685% of FLA)
♦ Code "J" for 5 Hp only
(up to 8.0 KVA/Hp = approx. 772% of FLA)

15. 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 7.99
LRA/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.

16. Table M-03 -- Maximum Motor Locked Rotor Currents
Motor Voltage - 60 Hz values
Rated
Horsepower
Code
Letters 200 Vac 208 Vac 230 Vac 460 Vac 575 Vac
5 F - J 106 102 92 46 37
7.5 F - H 147 142 128 64 51
10 F - H 186 179 162 81 65
15 F - G 267 257 232 116 93
20 F - G 334 321 290 145 116
25 F - G 421 405 366 183 146
30 F - G 499 480 434 217 174
40 F - G 667 641 580 290 232
50 F - G 833 801 724 362 290
60 F - G 1,001 962 870 435 348
75 F - G 1,249 1,201 1,086 543 434
100 F - G 1,668 1,603 1,450 725 580
125 F - G 2,088 2,008 1,816 908 726
150 F - G 2,496 2,400 2,170 1,085 868
200 F - G 3,335 3,207 2,900 1,450 1,160
250 F - G 4,198 4,036 3,650 1,825 1,460
300 F - G 5,060 4,865 4,400 2,200 1,760
350 F - G 5,865 5,639 5,100 2,550 2,040
400 F - G 6,670 6,413 5,800 2,900 2,320
450 F - G 7,475 7,188 6,500 3,250 2,600
500 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 using
voltage proportion.
Induction Motor Locked Rotor
Currents

17. Motor Parameters – cont’d
Motor Stalled (Locked Rotor)
Power Factor = Approx 40%

18. Motor Parameters – cont’d
Motor Theory and Formulae
♦ Purpose – Electrical to Mechanical
♦ Energy Conversion
– Motor Starting Region (Rotary Solenoid)
– Running Region (Energy Converter)
♦ Motor Torque & Motor Current Draw
-vs- Speed Curves
♦ A-T-L-Starting
(Basic Motor Characteristics)
– Power Factor & Phase Angles
– Efficiencies

19. Motor Starting -vs-
Motor Running Regions

20. Motor Starting -vs-
Motor Running Regions
Motoring
Region
Starting Region

21. Motor Parameters – cont’d
Motor Torque Curve
Motor Torque and Pump Torque Curves

22. Motor Parameters – cont’d
Motor Torque Curve
Motor Torque and Pump Torque Curves

23. Motor Parameters – cont’d
Motor Current Curve
Motor Current -vs- RPM Curves
Rated Running Current = 100%

24. Motor Parameters – cont’d
Motor Current Curve
Motor Current -vs- RPM Curves
Rated Running Current = 100%
Motoring
RegionStarting Region

25. Motor Theory and Formulae
Motor Starting Region
For a Motor at Stall, Motor
Impedance is Constant. So:
I = E / Z (Ohm’s Law)
Current is Directly Proportional to
Motor Voltage. I.E.:
Motor Current = Voltage /
Impedance
Power Factor (P.F.) is Typically 30%
to 40% at Stall (and for most of the
starting region)

26. Motor Theory and Formulae
Motor Starting Region – cont’d
In the Starting (Accelerating) Region:
Torque is Proportional to the Square
of the Applied Motor Voltage
T = K1 x V2 -or- Since Current
is proportional to Voltage (see
above):
T = K2 x I2
Thus: Torque is also Proportional to
the Square of the Motor Current

27. Motor Theory and Formulae
Motor Starting Region – cont’d
Example of Starting Torque
Proportional to the Square of Applied
Motor Voltage.
E.G. 57% Volts = 33% Rated Stall

28. Motor Theory and Formulae
Motor 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)

29. Motor Running -vs-
Motor Starting Regions
Rated Torque (100%) times Rated Speed (E.g. 1750
RPM) yields Motor Rated Horsepower.

30. IV. Motor Starting
♦ General - Overview – Types of Reduction
– Voltage Reduction: Wye–Delta, Soft Start, and
Autotransformer
– Current Reduction: Primary Impedance (Primary
Resistor, Primary or Neutral Reactor)
– Motor Impedance (Wound Rotor)
♦ Two Specialty Types
– Medium Voltage – Four Common Types: A-T-L,
Primary Reactor, Neutral Reactor -and-
Autotransformer
– Low Voltage - Wound Rotor (Not U.L. Listed)

31. Motor Starting - cont’d
Eight (+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

32. Motor Starting – cont’d
Across-the-Line (Direct On Line)

33. Full
Voltage
Start
------------
Across-
the-Line

34. Motor Starting – cont’d
Across-the-Line (Direct On Line)

35. Motor Starting – cont’d
Part Winding Start
Note: The Motor Must be Wound
Specifically for Part Winding Starting.

36. Part
Windin
g Start

37. Motor Starting – cont’d
Part Winding Start

38. Motor Starting – cont’d
Primary Resistor Start

39. Primary Reactor Start

40. Motor Starting – cont’d
Primary Resistor Start
Note: 65% Resistor Impedance is
1.24 - 0.40 = 0.84 pu

41. Motor Starting – cont’d
Primary Reactor Start

42. Motor Starting – cont’d
Primary (or Neutral) Reactor
Start
Note: 65% Reactor Impedance is
1.54 – 1.00 = 0.54 pu

43. Motor Starting Torque
Comparison
Curves B, C & D are at 65% Motor Starting
Voltage
(Reference Source Credit on Next Slide)
“0”
“0”

44. Motor Torque Comparison – cont’d
A=ATL, B=A.T., C=Pri. Res., D=Reactor
Gerhart W. Heumann (G.E.), “Magnetic
Controls of Industrial Motors”, Wiley &
S

45. Motor Starting – cont’d
Primary (or Neutral) Reactor
Start

46. Wye-
Delta
Open
Transitio
n

47. Motor Starting – cont’d
Wye-Delta Open Transition
LPM Module = Leading Phase Monitor®

48. First Half Cycle Offset
Waveforms
2.83 x LRA = 6 x 2.83 x FLA = 17.0 x FLA
Maximum Theortical This curve shows starting a motor which
still has BACK EMF (voltage) present.

49. Motor Starting – cont’d
Wye-Delta Open Transition

50. Motor Starting – cont’d
Wye-Delta Open Transition

51. Motor Starting – cont’d
Wye-Delta Open Transition

52. Motor Starting – cont’d
Wye-Delta Transition Hazard
Closed
Leading
Lagging

53. Motor Starting – cont’d
Wye-Delta Closed Transition

54. Wye-Delta Closed
Transition

55. Motor Starting – cont’d
Wye-Delta (Open or Closed Xtn.)

56. Wye-Delta
Starting;
Truths
and Myths
Page 1 of 4

57. Wye-Delta
Starting;
Truths
and Myths
Page 2 of 4

58. Wye-Delta
Starting;
Truths
and Myths
Page 3 of 4

59. Wye-Delta
Starting;
Truths
and Myths
Page 4 of 4

60. Motor Starting - cont’d
Soft (Solid State - SCR) Start

61. Soft Start (Solid State - SCR)

62. Motor Starting - cont’d
Soft (Solid State - SCR) Start

63. Motor Starting - cont’d
Autotransformer Start

64. Autotransformer Start

65. Motor Starting - cont’d
Autotransformer Start

66. Motor Starting
Characteristics
Parameter Chart
Fire Pump Starting Type Characteristics
- for -
Electric Fire Pump Motors and Controllers
Starting Characteristics (at Stall) -- Typical Values -for- Fully Load Pump (1)
Starting Starting Starting Accelerate
Motor Motor Amps Amps Starting Power Starting Full Load
Type 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)
Primary Resistor Any 2 Yes 65 390 80 314 42 Yes (c)
Primary 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)

67. Motor Starting
Characteristics
Parameter 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 not
accelerate 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 three
and 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 loaded
pump if it has no large torque dip or cusp. See the text discussion on Part Winding Starting
for 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 a
fully 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 and
maximum 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.

68. 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

69. Motor Running - cont’d
Variable Speed Running
♦ Wound Rotor Control
- Changes Motor Secondary Impedance -and-
- Motor Torque Curve
♦ Variable Frequency - Variable Speed
Control (VFDs)
- Changes Motor Torque and Current Curves
- Changes Motor Synchronous Speed –and-
- Changes Motor Running (Loaded) Speed

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

71. Wound Rotor Speed-Torque
Curves
- Flipped and Rotated -
Gerhart W. Heumann (G.E.), “Magnetic
Controls of Industrial Motors”, Wiley &
S

72. VFD = Motor Running Only
(No Motor Starting Region)
Starting Region
(Reference Only)

73. Variable Speed
Controllers
Power Circuit Schematic
. .
* Was Optional

74. Variable
Speed
Control

75. VFD – Principles of
Operation
3 Phase
Line Freq.
AC / DC
Smoothing
DC / AC
At “X” Khz

76. VI. Motor Wiring – Motor Lead
Configurations (Fourteen)
♦ Three Lead – Three Coil
(Single Voltage) (T1-T3)
♦ Six Lead – Three Coil
– Wye Running (T1-T3 & T4-T6)
– Delta Running (T1-T3 & T4-T6)
♦ Parallel Run (Six Lead - Six Coil)
– T1-T3 and T7-T8 - or -
– Both Sets Labeled T1-T3

77. Motor Lead Configurations
3 Lead – 3 Coil - Wye Running

78. Motor Lead Configurations
3 Lead – 3 Coil - Delta Running

79. Motor Lead Configurations
6 Lead - 3 Coil - Wye Running

80. Motor Lead Configurations
6 Lead – 3 Coil - Delta Running

81. 6 Lead – 6 Coil - Wye Running
Parallel Running

82. 6 Lead – 6 Coil - Delta Running
Parallel Running

83. Motor Wiring – cont’d
♦ Nine Lead (Dual Voltage) (T1-T9)
– Wye Wound
– Delta Wound
– Suitable for Part Winding Start ?
♦ Twelve Lead (T1-T12)
– Dual Voltage
– Single Voltage (Parallel Run)

84. 9 Lead - 6 Coil - Wye Running
Series Running

85. 9 Lead - 6 Coil - Wye Running
Parallel Running

86. 9 Lead - 6 Coil - Delta Running
Series Running

87. 9 Lead - 6 Coil - Delta Running
Parallel Running

88. 12 Lead - 6 Coil - Wye Running
Series Running

89. 12 Lead - 6 Coil - Wye Running
Parallel Running

90. 12 Lead - 6 Coil - Delta Running
Series Running

91. 12 Lead - 6 Coil - Delta Running
Parallel Running

92. Typical 12 Lead Motor Wiring Diagram
Courtesy of Marathon Electric

93. Starting Methods -vs- Motor Types
Table M-04 - Motor and Starting 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

94. Motor Types -vs- Starting Types
Motor Description (a)
Starting Method(b)
Run Type Number of Leads Part
Winding
Wye (Star)
Delta(c)
Neutral
Reactor
"Other 5" Figure
Wye Run Three Lead No No No Yes 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
Delta Run Six Lead Parallel Some(d)
No No Yes 7-9
Wye Run Nine Lead Series No No Yes Yes 7-10
Wye Run Nine Lead Parallel Some(d)
No No Yes 7-11
Delta Run Nine Lead Series No No No Yes 7-12
Delta Run Nine Lead Parallel No(e)
No No Yes 7-13
Wye Run Twelve Lead Series No No Yes Yes 7-14
Wye Run Twelve Lead Parallel Some(d)
No Yes Yes 7-15
Delta Run Twelve Lead Series No Yes No Yes 7-16
Delta Run Twelve Lead Parallel Some(d)
Yes No Yes 7-17
Notes:
(a) The Motor "Type" (Wye or Delta) is the Running 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 used only 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 Suitability
Motor Types -vs- Starting Types

95. VII. Induction Motors --
Installation Considerations
♦ Physical
– Location - Ideally Within Site of Controller
– Motor Protection: Fire, Security, Other Hazards
♦ Access – All Sides & Conduit Access
♦ Electrical N.E.C. (NFPA 70) - §430 (& § 695)
– Conduit & Hubs
– Environmental
– Conductor Sizing – Incoming & Motor Circuit
– Voltage Drops: Start & Run
– Cable Impedances and Run Lengths
(See NEMA ICS-14)

96. Motor Installation – cont’d
Start-up (Commissioning)
♦ Current Measurements
♦ Voltage Measurements
♦ Estimating Motor Load
- FLA -vs- Voltage
- SFA (115%) - Max. Allowed Under
Any Conditions (Temperature,
Altitude, Voltage Imbalance) on
ANY Phase

97. Motor Installation – cont’d
Environmental
♦ Open Drip Proof (ODP)
♦ Totally Enclosed Fan Cooled (TEFC)
♦ Outdoor
♦ Hazardous Locations, Explosion Proof:
– Motor, Controller, Wiring
♦ Other
– Salt Air
– Wind Blown Sand or Dust
– Temperatures
– Altitude

98. Questions ?
Jim Nasby,
Columbia Engineering
847-677-3468
JamesSNasby@ieee.org