# Transformer question blowing fuses



## Jack30802 (Jul 6, 2013)

Have a machine that has a 3kva 480 to 110 and just wanted to know if anyone heard of transformer cause large fuse at throw switch to pop with out tripping anything else ?


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## Safari (Jul 9, 2013)

Jack30802 said:


> Have a machine that has a 3kva 480 to 110 and just wanted to know if anyone heard of transformer cause large fuse at throw switch to pop with out tripping anything else ?


I didn't get your question right. did. you mean you have a transformer with a fuse that. will open incase of. fault without tripping anything else


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## Jack30802 (Jul 6, 2013)

No I'm not at machine just going by what one of the guys I work with that's there is saying he said that a fuse blown at the main disconnect that feed a breaker panel then it goes from there to 3 machine that have there own control panels and is saying one of the transformer In one of the control cabinet is the reason why it blew the main fuse just wouldn't think a small transformer would do that


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## wendon (Sep 27, 2010)

Is it a Time delay fuse? Has someone let the magic smoke out of the transformer? Does the transformer have a fuse inside the cabinet that protects it? What type of machine? Need mo info!


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## Hmacanada (Jan 16, 2014)

Jack30802 said:


> No I'm not at machine just going by what one of the guys I work with that's there is saying he said that a fuse blown at the main disconnect that feed a breaker panel then it goes from there to 3 machine that have there own control panels and is saying one of the transformer In one of the control cabinet is the reason why it blew the main fuse just wouldn't think a small transformer would do that


Dead short at the transformer?
If so absolutely could. Depending on install .
Fault currents


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## wildleg (Apr 12, 2009)

of course that could happen. without a doubt. did anyone check the trip setting at the main versus the subpanel/disconnect, etc.?


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## Jack30802 (Jul 6, 2013)

There wires that's buried in ground are shorted how would you check for short because when you ohm the 2 legs feeding transformer it ohms out to 0 but I check another and get the same reading the transformer feed is on a breaker


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## wildleg (Apr 12, 2009)

Jack30802 said:


> There wires that's buried in ground are shorted how would you check for short because when you ohm the 2 legs feeding transformer it ohms out to 0 but I check another and get the same reading the transformer feed is on a breaker


you disconnect them and meg. are you expecting us to believe that noone thought of that ? are you an electrician ? are you Cletis ? What's up with a question like this ?


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## Jack30802 (Jul 6, 2013)

So actually meg transformer ?


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## JRaef (Mar 23, 2009)

Jack30802 said:


> Have a machine that has a 3kva 480 to 110 and just wanted to know if anyone heard of transformer cause large fuse at throw switch to pop with out tripping anything else ?


Without knowing enough of what you have to give anything more useful, the answer is, yes, it could happen. A transformer, ANY transformer, has what is called "inrush current" when you first apply power to it. That inrush current can theoretically be as much as 20X the FLA of the transformer under the right circumstances. That's why you are supposed to use Time Delay Fuses feeding it. We don't know what you mean by "large fuses" so no way to offer any more help than that.


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