Transformer rating; apparent power?

[CPM]

Hi

I've got a uni assigment which includes build an equivalent circuit.
The transformer is rated at 2.2kVA which I thought was the apparent power.
But if I calculate the apparent power by using Vp x Ip then I get 220VA.
To find the phase angle Im confused do I use the 2.2kVA or 220VA for the following
cos-1(realpower/apparent).
Help needed please.
Cheers

 

[The Ghost]

How about a bit of research?
True, Reactive, and Apparent Power : Power Factor - Electronics Textbook - http://www.allaboutcircuits.com/textbook/alternating-current/chpt-11/true-reactive-and-apparent-power/

 

[CPM]

How about a bit of research?
True, Reactive, and Apparent Power : Power Factor - Electronics Textbook - http://www.allaboutcircuits.com/textbook/alternating-current/chpt-11/true-reactive-and-apparent-power/

Yeah i found that but it doesnt answer my question, which I didnt lay out very when.
When performing an open circuit test. To I recalculate the apparent power, which is this case will give me 220VA or do I use the rated power which is 2.2kVA?

 

[The Ghost]

Well surely you are trying to find the PF no? which is True power/apparent power. As you say in your opening words the KVA is the rated power. What exactly is it you are trying to do? Anyway hope some industrial spark comes along and enlightens both of us on this.

 

[CPM]

Well surely you are trying to find the PF no? which is True power/apparent power. As you say in your opening words the KVA is the rated power. What exactly is it you are trying to do? Anyway hope some industrial spark comes along and enlightens both of us on this.

Trying to find the phase angle of the no load current.

 

[Lucien Nunes]

'Rated power' means the maximum power the TX can handle at rated voltage without overheating, i.e. under full load conditions. You are talking about a no-load test, so the rated power is unimportant here. The power you are interested in is the one you calculate from the Vp and Ip measured under no-load conditions, which I assume is the 220VA figure mentioned.

The rated power becomes relevant when deciding what current to apply for a short-circuit test.

 

[CPM]

'Rated power' means the maximum power the TX can handle at rated voltage without overheating, i.e. under full load conditions. You are talking about a no-load test, so the rated power is unimportant here. The power you are interested in is the one you calculate from the Vp and Ip measured under no-load conditions, which I assume is the 220VA figure mentioned.

The rated power becomes relevant when deciding what current to apply for a short-circuit test.

Thats brilliant. Cheers for your help.
Now I've calculated Resistive and Inductive current. Core loss resistance and magnetising reactance.
Now for the short circuit test the Transformer Rated current is needed. How is that calculated?
Cheers

 

[CPM]

I've got the short circuit primary voltage as 15V and power as 50W.