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Muthuvel
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Join Date: Jun 2012
Posts: 115

Relay Protection for Motor

09/08/2012 12:51 AM

can anybody list out what are the fault relay protection needed for motor protections
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Crabtree
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Join Date: Jul 2007
Location: Commissariat de Police, Nouvions, occupied France, 1942.
Posts: 2599
Good Answers: 77
#1

Re: relay protection for motor

09/08/2012 4:07 AM

Yes, Guv. Anybody can do this when they see the motor rating plate, because the full load current is stamped onto the plate.

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TonyS
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United Kingdom - Member - New Member

Join Date: Aug 2010
Location: Resting under the Major Oak
Posts: 4347
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#2

Re: relay protection for motor

09/08/2012 7:50 AM

Sorry the homework answering sevice is off line.

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pnaban
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Join Date: Jun 2010
Location: srilanka
Posts: 2725
Good Answers: 5
#3

Re: Relay Protection for Motor

09/09/2012 1:25 AM

OC,SC,EF,phase reversal,phase unbalance,phase failure,winding temperature,under-current,bearing temperature etc depending on the rating of the motor.

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electricalexpert65
Guru

Join Date: Oct 2009
Posts: 2061
Good Answers: 169
#4

Re: Relay Protection for Motor

09/09/2012 9:31 AM

It depnds upon many factors.

MOTOR PROTECTION - How Much Protection is enough?

The answer depends on:

Rewinding Cost

Loss of Production

Effect on Downtime

New versus old installation

Need for communication

Metering & Control

MOTOR PROTECTION - PRACTICES

Less than 10kW: Bimetal Overload Relay with built-in protection against single-phasing

10kW to 50kW:

Thermal Overload

Over current

Earth fault

Unbalance

Locked Rotor

50kW & above:

Thermal overload

Over current

Earth fault

Locked Rotor

Unbalance

Repeat Starts

Under load

Prolonged Start

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V.I.Abraham
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Safety - ESD - New Member India - Member - New Member Engineering Fields - Energy Engineering - New Member

Join Date: May 2007
Location: Pune , India
Posts: 875
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#5

Re: Relay Protection for Motor

09/09/2012 11:53 PM

This is a normal general question which I used to ask candidates coming for job interviews or written tests. You need to study the subject to answer.

Better read the following link .This may help you.

http://www.l-3.com/wp/wp-content/uploads/2010/10/Motor-Protective-Settings1.pdf
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obouill
Commentator
France - Member - New Member

Join Date: Feb 2012
Location: Grenoble, France
Posts: 76
Good Answers: 4
#6

Re: Relay Protection for Motor

09/10/2012 4:15 AM

Refer to :

http://www.electrical-installation.org/enwiki/Motor_protection_functions
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Users who posted comments:

Crabtree (1); electricalexpert65 (1); obouill (1); pnaban (1); TonyS (1); V.I.Abraham (1)

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