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IEC Standards vs. NEMA Standards for Electrical Performance

What is IEC?

IEC is also known as the International Electrotechnical Commission. IEC is a European based organization that sets and publishes standards for mechanical and electrical equipment worldwide.

What is NEMA?

NEMA is also known as the National Electrical Manufacturers Association. NEMA is a North American based organization that sets and publishes standards for mechanical and electrical equipment throughout North America.

What’s the takeaway? Although they are standards defined for different locations, IEC and NEMA motors have similar output power, efficiency ratings, and size.

Dimensional & Frame Comparison

IEC Standard are expressed in metric units while NEMA frame standards are expressed in imperial units. IEC motors are commonly made with cast aluminum or cast iron frames whereas NEMA motors are commonly made with rolled steel or cast iron frames.

NEMA Motors are made with the conduit box mounted on the side of the motor frame (F1 or F2 position) while IEC motors are made with the conduit box mounted on top the motor frame (F3 position) as seen in the below in Figure 1. NEMA motors are compatible with a C face kit and a D flange whereas the IEC frames are compatible with a B14 face and a B5 Flange.

 

Diagram of three different frame mounts, F-1 Mount, F-2 Mount, F-3 Mount

Figure 1: NEMA vs. IEC Mount

 

 

Diagram showing NEMA vs IEC Dimension and HP Comparison
Figure 2: NEMA vs IEC Dimension and HP Comparison

IEC/NEMA COMPARISON

 

  DIMENSION IN MILLIMETERS KW/HP~ FRAME ASSIGNMENTS
3 Phase-TEFC
ICE NEMA D E F H U BA N-W 2 Pole 4 Pole 6 Pole
56 NA 56
-		 45
-		 35.5
-		 5.8
-		 9
-		 36
-		 20
-		 -
-		 -
-		 -
-
63 NA 63
-		 50
-		 40
-		 7
-		 11
-		 23
-		 .25KW
1/3HP		 .18KW
1/4HP		 -
-		 -
-
71 42 71
66.7		 56
44.5		 45
21.4		 7
7.1		 14
9.5		 45
52.4		 30
-		 .55
3/4		 .37
1/2		 -
-
80 48 80
76.2		 62.5
54		 50
34.9		 10
8.7		 19
12.7		 50
63.5		 40
38.1		 1.1
1-1/2		 .75
1		 .55KW
3/4HP
90S 56 90
88.9		 70
61.9		 50
38.1		 10
8.7		 24
15.9		 56
69.9		 50
46.6		 1.5
2		 1.1
1-1/2		 .75
1
90L 56 90
88.9		 70
69.8		 62.5
50.8		 10
8.7		 24
22.2		 56
57.2		 50
57.2		 2.2
3		 1.5
2		 1.1
1-1/2
100L 145T 100
88.9		 80
69.8		 70
63.5		 12
8.7		 28
22.2		 63
57.2		 60
57.2		 3
4		 2.2
3		 1.5
2
112L 182T 112
114.3		 95
95.2		 57
57.2		 12
10.7		 28
28		 70
70		 60
69.9		 3.7
5		 2.2
3		 1.5
2
112M 184T 112
114.3		 95
95.2		 70
68.2		 12
10.7		 28
28		 70
70		 60
69.9		 3.7
5		 4
5-4/5		 2.2
-
132S 213T 132
133.4		 108
108		 70
69.8		 12
10.7		 38
34.9		 89
89		 80
85.7		 7.5
10		 5.5
7-1/2		 3
-
132M 215T 132
133.4		 108
108		 89
88.8		 12
10.7		 38
34.9		 89
89		 80
85.7		 -
-		 7.5
10		 5.5
7-1/2
160M* 254T 160
158.8		 127
127		 105
104.8		 15
13.5		 42
41.3		 108
108		 110
101.6		 15
20		 11
15		 7.5
10
160L* 256T 160
158.8		 127
127		 127
127		 15
13.5		 42
41.3		 108
108		 110
101.5		 18.5
25		 15
20		 11
15
180M* 284T 180
177.8		 139.5
139.8		 120.5
120.2		 15
13.5		 48
47.6		 121
121		 110
117.5		 22
-		 18.5
25		 -
-
180L* 286T 180
177.8		 139.5
139.8		 139.5
139.8		 15
13.5		 48
47.6		 121
121		 110
117.5		 22
-		 18.5
25		 -
-
200M* 324T 180
203.3		 159
158.8		 133.5
133.4		 19
16.7		 55
54		 133
133		 110
133.4		 30
40		 30
40		 -
-
200L* 326T 200
203.2		 159
158.8		 152.5
152.4		 19
16.7		 55
54		 133
133		 110
133.4		 37
50		 37
50		 22
30
225S* 364T 225
228,6		 178
117.8		 143
142.8		 19
16.7		 60
60.3		 149
149		 140
149,2		 -
-		 37
50/75		 30
40
225M* 365 225
228.6		 178
177.8		 155.5
155.6		 19
16.7		 60
60.3		 149
149		 140
149.2		 45
60/75		 45
60/75		 37
50
250M* 405T 250
254		 203
203.2		 174.5
174.6		 24
20.6		 65
73		 168
168		 140
182.2		 55
75/100		 55
75/100		 -
-
280S* 444T 280
279.4		 228.5
228.6		 184
184.2		 24
20.6		 75
85.7		 190
190		 140
215.9		 -
-		 -
-		 45
60/100
280M* 445T 280
279.4		 228.5
228,6		 209.5
209.6		 24
20.6		 75
85.7		 190
190		 140
215.9		 -
-		 -
-		 55
75/125

 

 

 

Cooling and Insulation Duty Cycle Index

IEC motors has additional designations indicating how the motor is cooled which is represented by a two-digit IC code, where as NEMA enclosure designation indicates how the motor is cooled.

 

 

IEC NEMA
IC 01 Open Design
IC 40 TENV
IC 41 TEFC
IC 48 TEAO

NEMA Classes

NEMA motors commonly have 4 winding insulation classes: A, B, F and H, based on the max temperature ratings with a reference to a 40°C ambient temperature.

NEMA also specifies the allowable temperature rises for motors operating under full load at certain service factors.

Example: For a Class B insulated, 1.15 SF motor, if we add the NEMA allowable rise of 80°C to the reference ambient temperature of 40°C: result is a motor with an operating temperature of 120°C.

 

 

Class: A 105° C
Class: B 130° C
Class: F 155° C
Class: H 180° C

 


 1.0 SF 1.15 SF
Class: A 60°C 70°C
Class: B 80°C 90°C
Class: F 105°C 115°C
Class: H 125°C

IEC Classes

IEC motors identify multiple thermal classes based on the maximum allowable temperature.

Note: Duty cycles are different. Where NEMA commonly designates either continuous, intermittent, or special duty (typically expressed in minutes), IEC uses eight duty cycle designations.

 

IEC Thermal Class Designation Letter Designation
90 Y
105 A
120 E
130 B
155 F
180 H
200 N
220 R

IEC Duty Cycle Designations Guide

S1 Continuous duty. The motor works at a constant load for enough time to reach temperature equilibrium.
S2 Short-time duty. The motor works at a constant load, but not long enough to reach temperature equilibrium, and the rest periods are long enough for the motor to reach ambient temperature.
S3 Intermittent periodic duty. Sequential, identical run and rest cycles with constant load. Temperature equilibrium is never reached. Starting current has little effect on temperature rise.
S4 Intermittent periodic duty with starting. Sequential, identical start, run and rest cycles with constant load. Temperature equilibrium is not reached, but starting current affects temperature rise.
S5 Intermittent periodic duty with electric braking. Sequential, identical cycles of starting, running at constant load, electric braking, and rest. Temperature equilibrium is not reached.
S6 Continuous operation with intermittent load. Sequential, identical cycles of running with constant load and running with no load. No rest periods.
S7 Continuous operation with electric braking. Sequential identical cycles of starting, running at constant load and electric braking.
No rest periods.
S8 Continuous operation with periodic changes in load and speed.
Sequential, identical duty cycles of start, run at constant load and given speed, then run at other constant loads and speeds.
No rest periods.

 

NEMA motor efficiencies have two standard levels defined as “Energy Efficient” and “Premium Efficient” in the NEMA standards. NEMA Premium is trademarked and the term should only be used by manufacturers who are part of NEMA’s premium motor program. IEC 60034-30-1 defines the efficiency classes for motors. IEC IE2 is equivalent to energy efficient and IE3 is mostly equivalent to premium efficiency.

 

 

Efficiency Levels for 60 Hz Motor Designs
NEMA IEC
N/A IE1
Energy Efficient IE2
Premium Efficient IE3

 

IEC and NEMA designs have a wide range of electric motors available, understanding the differences and similarities between these two design standards will help you select the right motor for your application. To find the right motor for you, visit the Regal Rexnord NEMA Motors Catalog or the IEC Motors Catalog. 

 

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