04/04/2022

Size of earthing conductor in rotating machines

Earthing connection

  • Each machine is provided with earthing terminal however, the machine shall be neither earthed nor provided earth terminal when
  • They fitted with supplementary insulation
  • They have rated voltage up to 50 V AC or 120 V DC and are intended to do SELV circuit. 
  • If the machine rating greater than 50 V AC or 120 V DC but not exceeding 1000 V AC or 1500 V DC, the terminal for earthing conductor is provided in the terminal box. 
  • If the rating of machine greater than 100 kW or 100 kVA, the earthing terminal shall be provided on the frame.
  • If the rotor winding and bearing of a machine is insulated, the shaft shall be electrically connected with earthing terminal unless the manufacture provided separate protection for it.

You may also like to read this articles :

What is tertiary winding?

Construction and working of earthing transformer

Construction and working of hysteresis motor

Compare distribution transformer and power transformer

 

Size of earthing conductor

The size of earthing conductor

  • That of live conductor if the cross-section area of live conductor less than 25 mm2
  • 25 mm2 if the cross-section area of live conductor lies between 25 mm2 and 50 mm2
  • 50% that of live conductor if the cross-section area of live conductor exceeds 50 mm2

Cross section area of earthing conductor


Cross section area of live conductor ( mm2 )

Cross section area of earthing conductor ( mm2 )

4

4

6

6

10

10

16

16

25

25

35

25

50

25

70

35

95

50

120

70

150

70

185

95

240

120

300

150

400

185

 


No comments:

Post a Comment