LV Switchgear

Considering the short circuit fault, which switchgear is preferable, SFU OR MCCB? Which operates faster?
which one is popular in Indian Market and why?
2) Define SCPD. What is type2 co-odination?

3) Why the contactor rating is higher for the fuseless selection than for fuse selection? whether the ratinf of SFU or MCCB remains the same in both the cases?

4) If the HP rating is known then can you calculate the ratings of L.V Switchgear(SFU/MCCB, contactor, OLR) without using the selection chart?

Questions by jayashreeraut

Showing Answers 1 - 4 of 4 Answers

veena_gyanchandani

  • Feb 22nd, 2010
 

During short circuit faults, the most reliable switchgear is SFU. It is fastest to operate and takes only a few miliseconds to operate.
The operator just has to replace the blown fuse in SFU.
MCCB is better than SFU for overvoltage protection.

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veena_gyanchandani

  • Feb 24th, 2010
 

During short ckt. faults, the most reliable switchgear is SFU. It is fastest to operate and takes only few miliseconds. The operator just has to replace the fuse.
MCCB is good for overload protection.

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veena_gyanchandani

  • Feb 24th, 2010
 

2) SCPD - Short Ckt. Protection Device.eg - SFU.
Type 2 coordination says that there should be no danger to personnel as well as no damage to the controller for downstream faults.
Light contact welding is allowed that could break on on-off operation.
Benefits of Type 2 coordination are safety, reduced cost, increased productivity etc.

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