Standard motors and ratings

Standard motor features

There is no IEC publication covering standard ratings associ­ated with frame sizes, but British Standard BS 5000 : Part 10 does give ratings against frame size and shaft number gener­ally from 56 up to 315 sizes depending upon the type of motor. Although this standard was first published during 1978, and has been amended more recently, it is still current and forms the ba­sis for standard ratings for motors within this range.

The motors covered by the Standard are described as “general purpose induction motors” and meet various parts of British Standard BS 4999 (this generally therefore meets the IEC pub­lications on which BS 4999 is based where appropriate). The motors are suitable for connecting to 3-phase, 415 V, 50 Hz supplies but by agreement may be wound for any voltage not exceeding 660 V. Class E, Class B or Class F insulation may be used with the ambient conditions not exceeding 40°C or 1000 m altitude. BS 5000: Part 10 should be consulted for full details.

Standard motor ratings

The standard ratings are specified for single-speed motors with synchronous speeds of 3000,1500,1000 or 750 r/min. Inmost cases the shaft sizes are the same for all speeds, except for 3000 r/min on some of the larger standard frame sizes.

Table 13.6 gives standard outputs and shaft sizes for totally en­closed fan-ventilated (TEFC) cage motors where the cooling system is defined as IC411 and the degree of protection as IP44. These motors are fitted with either feet or flanges. The standard allows the same ratings for airstream rated motors with feet or flanges without specifying the air velocity.

Frame No.

Output (kW)

Shaft No.

Synchronous speed (r/min)

3000

1500

1000

750

3000

1500 or less

D56

0.09 & 0.12

0.06 & 0.09

9

9

D63

0.18 & 0.25

0.12 & 0.18

11

11

D71

0.37 & 0.55

0.25 & 0.37

14

14

D80

1.1

0.75

0.55

19

19

D90S

1.5

1.1

0.75

0.37

24

24

D90L

2.2

1.5

1.1

0.55

24

24

D100L

3

2.2 &3

1.5

0.75 & 1.1

28

28

D112M

4

4

2.2

1.5

28

28

D132S

5.5 & 7.5

5.5

3

2.2

38

38

D132M

7.5

4 & 5.5

3

38

38

D160M

11 & 15

11

7.5

4 & 5.5

42

42

D160L

18.5

15

11

7.5

42

42

D180M

22

18.5

48

48

D180L

22

15

11

48

48

D200L

30 & 37

30

18.5 & 22

15

55

55

D225S

37

18.5

55

60

D225M

45

45

30

22

55

60

D250M

55

55

37

30

60

65

D280S

75

75

45

37

65

75

D28CM

90

90

55

45

65

75

D315S

110

110

75

55

65

80

D315M

132

132

90

75

65

80

Table 13.6 Standard outputs and shaft numbers for totally enclosed fan-ventilated (TEFC) cage motors

In the case of airstream rated motors with pad or mountings classified as IC418, the ratings are as given in Table 13.7 with the average air velocity at least the value given by Table 13.8 when measured 50mm radially from mounting pads.

Frame

No.

Output (kW)

Shaft No.

Synchronous speed (r/min)

3000

1500

1000

750

3000

1500 or less

D80

1.1

0.75

0.55

19

19

D90L

1.5 & 2.2

1.01 & 1.5

0.75 & 1.1

0.37 & 0.55

24

24

D100L

3

2.2 &3

1.5

0.75 & 1.1

28

28

D112M

4

4

2.2

1.5

28

28

D132M

5.5 & 7.5

55 & 75

3, 4 & 5.5

2.2 &3

38

38

D160L

11, 15 & 18.5

11 & 15

7.5 & 11

4, 5.5 & 7.5

42

42

D180L

22

18.5 & 22

15

11

48

48

D200L

30 & 37

30

18.5 & 22

15

55

55

D225M

45

37 & 45

30

18.5 & 22

55

60

D250M

55

55

37

30

60

65

Table 13.7 Standard outputs and shaft numbers for pad or rod mounted cage motors

The standard ratings for enclosed ventilated cage motors are given in Table 13.9. These motors have a cooling system clas­sified as IC01 and a degree of protection classified as IP22.

Frame No.

Average air velocity (m/s)

Synchronous speed (r/min)

3000

1500

1000

750

D80

10

7.5

6.5

5

D90

12.5

9

7.5

6

D100

15

10

8

7

D112

16.5

11

9

7.5

D132

18

12

9.5

8

D160

19

12.5

10.5

8.5

D180

20

13.5

11

9

D200

21

14

11.5

9.5

D225

22

14.5

12

10

D250

23

15

12.5

10.5

Table 13.8 Average air velocity for cooling totally enclosed airstream rated motors

Output (kW)

Shaft No.

Frame No.

Synchronous speed (r/min)

3000

1500

1000

750

3000

< 1500

C160M

11, 15

11

7.5

5.5

48

48

C160L

18.5 & 22

15 & 18.5

11

7.5

C180M

30

22

15

11

55

55

C180L

47

30

18.5

15

C200M

45

37

22

18.5

60

60

C200L

55

45

30

22

C225M

75

55

37

30

60

65

C250S

90

75

45

37

65

75

C250M

110

90

55

45

C280S

110

75

55

65

80

C280M

132

132

90

75

C315S

160

160

110

90

70

90

C315M

200

200

132

110

Table 13.9 Standard outputs and shaft numbers for enclosed ventilated cage motors

It should be noted that the air velocities specified in Table 13.8 are in many cases extremely low for low hub-to-tip ratio axial flow fans which have a high flowrate. In consequence the air velocities flowing over the motor will be considerable greater than those given in the Table. The power produced can there­fore be appreciably greater, without exceeding safe tempera­ture rises in the windings or the motor surfaces. Fan motors may therefore take advantage of this situation provided that the nose motor bearing can accommodate both the increased torque requirement and also the radial and thrust loads im­posed by the fan impeller.

This has lead the major fan manufacturers, some of whom manufacture their own electric motors, to develop machines specifically appropriate to the application. Such solutions are especially the case in the smaller frame sizes where quantity requirements make such motors economically viable.

Posted in Fans Ventilation A Practical Guide


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