Current through primary winding?
- Thread starter EEC
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stew
Senior Member
- Location
- federal way,washington
magnetization current will flow. hence the hum when energized.
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
Agreed. There is a complete circuit, so current will flow, regardless of what is happening on the secondary.
shamsdebout
Senior Member
- Location
- Macon,GA
Dare I mention to add that this current the primary winding draws will be very low. Could even be less than 0.5% of the transformer's full load current, but sometimes 1-2%.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
110224-1953 est
EEC:
In an ideal transformer the primary current would be zero with no load on the secondaries. But we only have ideal transformers in our mind and on paper.
shamsdebout's comment is probably a reasonable value for a real world transformer.
The unloaded input current is non-linear and has a large inductive component. All the standby heat loss in the transformer translates to the no-load resistive component of the standby primary current.
At my website http://beta-a2.com/EE-photos.html see photo P8 for a scope picture of the unloaded excitation current to a transformer with nominal input voltage. The peaking of the current results from the core starting into saturation.
.
EEC:
In an ideal transformer the primary current would be zero with no load on the secondaries. But we only have ideal transformers in our mind and on paper.
shamsdebout's comment is probably a reasonable value for a real world transformer.
The unloaded input current is non-linear and has a large inductive component. All the standby heat loss in the transformer translates to the no-load resistive component of the standby primary current.
At my website http://beta-a2.com/EE-photos.html see photo P8 for a scope picture of the unloaded excitation current to a transformer with nominal input voltage. The peaking of the current results from the core starting into saturation.
.
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