Transformer mag current 1

[Marke]

Hi

What would be the typical range of magnetizing current for power transformers in the 50KVA - 500KVA 11KV/400V be? percent of rated current.

Best regards,
Mark

Mark Empson
Advanced Motor Control Ltd

 

[Skogsgurra]

Da bin ich überfragt.

Had to use a German expression that I recently learned. It means: "Just this question, I cannot answer with enough certainty, so I do not answer. Not this time. I can answer any other question, of course, but not this one. At least not with the certainty you need and deserve. You really ought to know what questions to ask! This is not a good question to ask."

Apart from that, it depends a lot on how close to saturation the flux is taken. And what the core material is. One guy that I know, is making a distribution transformer with extremely low magnetizing current. The reasoning is that rural distribution transformers idle a lot and that the idling losses shall be minimized. I will be back with his home page when I have found it.

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[prc]

There are two types of construction for this range of distribution transformers- with stacked core or wound cores with magnetizing currents of max 3 or 2 % of full load current. In case of wound core transformers, typical values are 0.5 % ( with best grade of CRGO)and 1.5 %( with standard grade of silicon steel). % current increases with smaller the kVA. Another interesting point is that no-load power factor of today's transformers is quite high 0.7-0.9 compared to 0.05-0.25 of yesterdays ( see Transformer Engineering -L.F Blume and others,John Wiley,1939,1951)This has happened due to the better manufacturing techniques used for core plus the drastic reduction in the exciting VA/kg of better grades of CRGO being used today. Reduction in VA/kg was quite high compared to reduction in W/kg .The ratio of VA/kg to W/kg at working flux density was 5-20(Blume) compared to today's less than 2.

 

[Skogsgurra]

There are no data available at the Hexaformer's site. Bu there's a video with "electroporn".

http://www.hexaformer.com/Video-about-Hexaformer.htm

If you browse the site (

http://www.hexaformer.com),

you will find data on idling and full load losses for different transformer sizes. But nothing on magnetizing current.

I think that prc's data for wound core transformers are close to what you find in these transformers.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.