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guruprasad
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Join Date: Feb 2011
Location: INDIA
Posts: 3

Design of Overcurrent Relay

02/26/2011 2:52 PM

Can someone out there help me design an overcurrent relay to protect a welding transformer whose load current measured through a C.T (current transformer) shows 2 amperes on secondary side of the C.T?
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Paulusgnome
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New Zealand - Member - Kiwi

Join Date: Oct 2007
Location: Christchurch, New Zealand
Posts: 328
Good Answers: 29
#1

Re: design of overcurrent relay

02/26/2011 3:54 PM

The simplest and surest way to protect your welding transformer is with a circuit breaker, either an MCB if your welder draws less than 63A or an MCCB if it draws more. The effort and cost involved in using the CT will almost certainly be greater for no real advantage.

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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: design of overcurrent relay

02/26/2011 4:13 PM

What sort of O/L do you want, thermal or instantaneous?

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guruprasad
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Join Date: Feb 2011
Location: INDIA
Posts: 3
#3
In reply to #2

Re: design of overcurrent relay

03/02/2011 9:19 AM

thermal overload.
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PWSlack
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United Kingdom - Member - Indeterminate Engineering Fields - Control Engineering - New Member

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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.
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#4
In reply to #3

Re: design of overcurrent relay

11/22/2018 9:27 AM

There's no point in designing one when numerous temperature-operated switches and relays exist on the open market already. An internet search engine will reveal them and then all that is needed is the correct selection of one that is suitable.

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