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Anonymous Poster #1

Fault Level for MCCB or MCB Selection.

10/24/2014 2:46 AM

Hi,

How to find fault levels for induction motors protection? Because upto 10 kA, we can use MCB and from 15kA to 65 kA we can use MCCB.

Regs,
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lyn
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Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: Fault level for MCCB or MCB selection.

10/24/2014 3:50 AM

Your assignment for tomorrow is to find what the purpose of a circuit breaker is.

Report your findings here.
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Anonymous Poster #2
#2

Re: Fault level for MCCB or MCB selection.

10/24/2014 3:54 AM

CR4 ADMIN: Deleted Post

Spam: This post was deleted because it contained advertising outside the Commercial Space forum. Please review Section 14 of the CR4 Site FAQ about advertising.
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lyn
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#3
In reply to #2

Re: Fault level for MCCB or MCB selection.

10/24/2014 4:01 AM

Reported as SPAM.
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ade_jkrs
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Join Date: Jun 2014
Posts: 19
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#4

Re: Fault level for MCCB or MCB selection.

10/24/2014 9:00 AM

Hi,

Prospective fault current at any point in an electrical installation is determined from the supply transformer (Tx) MVA, Tx p.u impedance, cable impedance between Tx and point of fault and rotating electrical machinery connected downstream from the fault. Whether the connected equipment is induction motor, or other plants/equipment is immaterial. Strictly speaking, it is not motors, but motor circuits that need protection from short circuits. Motors are protected from overloads by overload relay installed in a motor control panel.

Regards
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Crabtree
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Join Date: Jul 2007
Location: Commissariat de Police, Nouvions, occupied France, 1942.
Posts: 2599
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#5

Re: Fault level for MCCB or MCB selection.

10/24/2014 9:34 AM

Yout don't. These things are there to protect the cable!

If you want to protect the motor as well, use a motor overload device as well.

__________________
 Good moaning!
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Gareth
Participant

Join Date: Oct 2014
Posts: 2
#6

Re: Fault Level for MCCB or MCB Selection.

10/25/2014 5:35 AM

http://www.ece.mtu.edu/faculty/bamork/EE5223/Old_Rpts/file_2.pdf
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ade_jkrs (1); Anonymous Poster (1); Crabtree (1); Gareth (1); lyn (2)

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