Previous in Forum: Need Help With Motor Selection   Next in Forum: Two Phase Electricity
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
11 comments
Rate Comments: Nested
S SRINIVASAN
Associate

Join Date: Jan 2010
Posts: 25
Good Answers: 1

Design of MCC Feeder

06/30/2010 7:35 PM

As a case study for feeding a 90 KW motor, what are all the design criteria?

Sizing of conductor, selection of contator, cable size, earthing, etc.

Whether I should feed from the existing MCC or tap directly from the PCC in my sub-station.
Register to Reply
Pathfinder Tags: contactor sizing of conductor
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
Tornado
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21017
Good Answers: 795
#1

Re: Design of MCC feeder

06/30/2010 7:42 PM

Would this be a case study, or a basket case study?

Voltage? Motor FLA? How long of cable run to each location? What empty buckets of suitable size, if any, are available in each location? What type of starting method? And no doubt some other questions....

__________________
 In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
2
lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#2

Re: Design of MCC feeder

06/30/2010 7:43 PM

This question reeks of homework or untrained persons trying to perform tasks outside their area of competence.
Register to Reply Good Answer (Score 2)
Go to Next Good Answer
2
kvsridhar
Guru
India - Member - New Member

Join Date: Sep 2009
Location: Temporarily at Ashburn, VA
Posts: 2744
Good Answers: 164
#3

Re: Design of MCC Feeder

06/30/2010 9:44 PM

Tornado and Lynlynch are quite right you know, you should furnish more data. Also, you should do some searches and then come here when you hit a wall.

However, assuming you are in India, many companies here have readymade recommendations for what you seem to be needing. Here is a pdf from ABB: Starter kits

i am also assuming : this is not homework, voltage is 415V 3Φ, you are NOT looking for a solid-state starter, you have enough empty feeder space in your MCC. (Do not take this from your PCC). You should also be aware that you need to provide a proper SCPD for giving Type 2 co-ordination.

__________________
 Nothing worthwhile can ever be taught, it can only be learnt.
Register to Reply Good Answer (Score 2)
No more Good Answers.
kabeerta
Active Contributor
Technical Fields - Technical Writing - New Member Engineering Fields - Energy Engineering - New Member Fans of Old Computers - UNIVAC - New Member Hobbies - Automotive Performance - New Member Popular Science - Genetics - New Member Safety - ESD - New Member

Join Date: Jun 2010
Posts: 23
#4

Re: Design of MCC Feeder

07/01/2010 1:06 AM

Cable size- 4Run of 70 sqmm unarmoured copper cable
Contactor- 200Amps 3Pole- 3Nos
We are suggesting VFD / soft strter for this higher capacity motors. Star Delta starters will make more surge currents
Earthing- 25x3 Flat copper
If MCC is having capacity to feed additional 200Amps, You can connect to MCC through a MCCB, Otherwise feed from PCC in substation
Register to Reply Score 1 for Off Topic
Tornado
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 21017
Good Answers: 795
#5
In reply to #4

Re: Design of MCC Feeder

07/01/2010 1:32 AM

Sorry, but without the voltage, you don't know what the amps are, and so you cannot rate the contactor.

__________________
 In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply
electricalexpert65
Guru

Join Date: Oct 2009
Posts: 2061
Good Answers: 169
#6

Re: Design of MCC Feeder

07/01/2010 7:47 AM

I suggest you attend to our training programme on "Electrical Design of Switchgear Assemblies". Please mail me thro this forum for further details.
Register to Reply
Anonymous Poster
#8
In reply to #6

Re: Design of MCC Feeder

07/01/2010 10:15 PM

Dear sir,

I thankyou for your reply. you can contact me to my mail id ssnzc@yahoo.co.in

regards

s.srinivasan
Register to Reply
electricalexpert65
Guru

Join Date: Oct 2009
Posts: 2061
Good Answers: 169
#9
In reply to #8

Re: Design of MCC Feeder

07/02/2010 1:31 AM

Just now mailed you our latest training calender.
Register to Reply
PWSlack
Guru
United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

Join Date: Jan 2007
Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on.
Posts: 32175
Good Answers: 839
#7

Re: Design of MCC Feeder

07/01/2010 9:09 AM

→ British Standard 7671. <yawn>.

__________________
 "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
Register to Reply
BB Raina
Commentator

Join Date: Jun 2010
Posts: 75
#10

Re: Design of MCC Feeder

07/02/2010 2:07 AM

MCCs are usually used for feeding motors of KW rating < 55 KW. You have a 90 KW motor, I suggest you tap it directly from PCC in your substation. You should consider the following factors for feeding the motor successfully:

a) Check/ Review the bus bar rating of your PCC in the light of additional load of 90 KW.

b) Select a cable (Al/ Cu) based on FLC of motor. Apply derating factors based the route and method of laying you propose to follow. ( I mean u/g or o/h).

c) Distance between the motor and PCC for calculating voltage drop which should be not more than 10%.

d) The feeder feeding the motor should preferably be a circuit breaker (ACB) which are usually of 630A rating.

e) Choose appropriate protection system using integrated Motpro relay.

f) For internal earthing 1/2 C of the 3 1/2C X .... cable should be used. For external earthing 40X5 mm earthing strip to be used at both ends -PCC end and motor end.

BB Raina
Register to Reply
Anonymous Poster
#11

Re: Design of MCC Feeder

07/05/2010 8:51 AM

Why are you doing this if you havent got a clue on what to do? Why not ask for instructioons on how to defuse an explosive device?Just as dangerous.You obvioulsy have never seen a high voltage arc flash explosion, have you?

Check out this video:http

http://www.youtube.com/watch?v=4bBvmPRqfmo

Copy and paste if link doesn't work.

Do you still want to do this work for which you are obviously not qualified or prepared?
Register to Reply
Register to Reply
Have a Different Question?
11 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

Anonymous Poster (2); BB Raina (1); electricalexpert65 (2); kabeerta (1); kvsridhar (1); lyn (1); PWSlack (1); Tornado (2)

Previous in Forum: Need Help With Motor Selection   Next in Forum: Two Phase Electricity

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (70 right now)
Show Members
Advertisement