EARTHING STANDERDS FOR HT SWITCHGEAR AND HT MOTORS

[narsimha23]

IS THERE ANY DIFFERECNE BETWEEN A HT SWITCHGEAR AND HT MOTOR WHILE PROVIDING NO OF EARTH CONNECTIONS FOR ITS PROTECTION ? WHAT DOES IEC STANDERD SAY IN THIS REGARD ?IF IT IS NOT SAME ,THEN WHY SO ?

 

[peebee]

It's not clear what your asking -- can you rephrase the question?

 

[narsimha23]

AS PER IEC TWO EARTHING CONNECTIONS ARE PROVIDED TO A 3.3KV HT/415V LT PANEL WHERE AS ONLY ONE EARTHING CONNECTION IS SHOWN TO HT/LT MOTOR OV SAME VOLTAGE RATING.IS IT CORRECT ?IF SO GIVE TECH REASONS FOR IT ?. IN SHORT WHY TWO EARTH CONNECTIONS ARE PROVIDED TO HT PANEL WHERE AS HT MOTOR IS PROVIDED ONE EARTHING OF SAME VOLTAGE RATING ?I HOPE NOW THE QUESTION IS CLEAR ? WILL SOME MEMBER FROM IEC ANSWER?

 

[dpc]

narsimha23,

Please look around your computer keyboard for your caps lock and turn it off. All upper case is hard to read.

Multiple grounding connections to major equipment is common as an added margin of safety and to lower the impedance to ground. This is what we often call a "belt and suspenders" approach. If one is good, two are better.

I have no idea what IEC requirements are, but making two ground connections will not hurt anything.

 

[streeta]

Can someone tell me where i can look up the standards for all earth sizes, with a particular size conductor. (what size earth is needed for a cable)?. also where excatly the groundings should be (one on the motor the other at the switchgear)?.
Thankyou

 

[Janus101]

streeta,

Whilst several standards give certain guidelines, national codes will dictate earth conductor sizes alongside with the system application. What Im trying to say is; It depends...