Electrical Engineering - Transformers - Discussion
Discussion Forum : Transformers - General Questions (Q.No. 1)
1.
What kVA rating is required for a transformer that must handle a maximum load current of 8 A with a secondary voltage of 2 kV?
Discussion:
121 comments Page 1 of 13.
Santhosh said:
1 decade ago
Hello my dear friends we have to follow these steps to select transformer
we know that
p=VIcosQ for single phase and p=root3*v*i*cosQ for three phase
so power = 2000*8*0.95
= 15200= 15.2kw
Then
we know that power factor=KW/KVA
Consider 0.95 PF for transformer
0.80 PF for generator
so KVA=KW/PF=15200/0.95 = 16KVA
we know that
p=VIcosQ for single phase and p=root3*v*i*cosQ for three phase
so power = 2000*8*0.95
= 15200= 15.2kw
Then
we know that power factor=KW/KVA
Consider 0.95 PF for transformer
0.80 PF for generator
so KVA=KW/PF=15200/0.95 = 16KVA
Madhusudhan. M said:
1 decade ago
It's simple. A transformer transfors electrical power at one level of voltage & current to another another level of voltage & current without any change. With this basics we can say,
Apparent power=KVA= V1 * I1 = V2 * I2,
So, here KVA Rating = v2 * i2 = 2 kv * 8 A
= 16 KVA
Apparent power=KVA= V1 * I1 = V2 * I2,
So, here KVA Rating = v2 * i2 = 2 kv * 8 A
= 16 KVA
Jayadeva said:
9 years ago
The output power of transformer is depending pf, so it is not to be rated for kw.
ex, if v = 10V.
A = 2A.
pf = 0.8.
P = v * i * pf .
p = 10 * 2 * 0.8 ,
p = 16w.
And
p = v * i.
p = 10 * 2,
p = 20.
ex, if v = 10V.
A = 2A.
pf = 0.8.
P = v * i * pf .
p = 10 * 2 * 0.8 ,
p = 16w.
And
p = v * i.
p = 10 * 2,
p = 20.
Sanchayan Singha Roy said:
5 years ago
In the question, it is said that the load current is 8A and the secondary voltage is 2KV.
We know that the kva rating of a transformer remains constant be it in primary side or secondary side.
so,
V1*I1= V2*I2.
V2 = 2KV,
I2 = 8A.
KVA rating = V2*I2.
= 2*8 kVA,
= 16 KVA.
We know that the kva rating of a transformer remains constant be it in primary side or secondary side.
so,
V1*I1= V2*I2.
V2 = 2KV,
I2 = 8A.
KVA rating = V2*I2.
= 2*8 kVA,
= 16 KVA.
(11)
Sudipt jena said:
1 decade ago
Transformer is always rated in kva or mva instead of kilowatt or megawatt because of the absence of power factor unlike the motors. And this kva or mva can be derived by multiplying the system voltage with the current. Here the system voltage is 2000 volts and current is 8 amp.
Kiran said:
1 decade ago
Guys, some come across true power and apparent power and some tell us about copper lose and core loss but I am convinced with @Santosh answer after that @Sudipt told there will be no pf then its tricky again want to know pf should be considered or not in calculation.
Athi said:
1 decade ago
We know that
p=VIcosQ for single phase and p=root3*v*i*cosQ for three phase
So power = 2000*8*0.95
= 15200= 15.2kw
Then
We know that power factor=KW/KVA .
Consider 0.95 PF for transformer.
0.80 PF for generator.
So KVA=KW/PF=15200/0.95 = 16KVA.
p=VIcosQ for single phase and p=root3*v*i*cosQ for three phase
So power = 2000*8*0.95
= 15200= 15.2kw
Then
We know that power factor=KW/KVA .
Consider 0.95 PF for transformer.
0.80 PF for generator.
So KVA=KW/PF=15200/0.95 = 16KVA.
Hakim said:
10 years ago
Apparent Power (VA) = Root-square 3*V*I. That is for 3 phase transformers only.
Apparent Power (VA) = V*I. That is for single phase transformers only.
In the equation they did not mentions the type of the transformer either single or three phase.
Apparent Power (VA) = V*I. That is for single phase transformers only.
In the equation they did not mentions the type of the transformer either single or three phase.
ADITYA PRASAD TRIPATHY said:
1 decade ago
We know that KVA=VOLATGE*CURRENT/1000
SO VOLTAGE =2 KV= 2000 VOLT
CURRENT=8 AMP
SO KVA = 2000 * 8 / 1000
=16000 /1000
16
SO KVA=16 SO SIMPLE.
SO VOLTAGE =2 KV= 2000 VOLT
CURRENT=8 AMP
SO KVA = 2000 * 8 / 1000
=16000 /1000
16
SO KVA=16 SO SIMPLE.
L P RAI said:
1 decade ago
We know
E2/E1=N2/N1=I1/I2
>E2/E1= I1/I2
>E1*I1=E2*I2
=2Kv *8A
=16 KVA
We should note (in this question) the rating of transformer meanse input kva rating the out put voltage and current i.e load current is already given.
E2/E1=N2/N1=I1/I2
>E2/E1= I1/I2
>E1*I1=E2*I2
=2Kv *8A
=16 KVA
We should note (in this question) the rating of transformer meanse input kva rating the out put voltage and current i.e load current is already given.
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