Download How to Calculate/Find the Rating of Transformer in kVA (Single

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Document related concepts

Electrical ballast wikipedia, lookup

Ground (electricity) wikipedia, lookup

Current source wikipedia, lookup

Chirp spectrum wikipedia, lookup

Power engineering wikipedia, lookup

Stepper motor wikipedia, lookup

Ohm's law wikipedia, lookup

Electrical substation wikipedia, lookup

Buck converter wikipedia, lookup

Bode plot wikipedia, lookup

Surge protector wikipedia, lookup

Rectifier wikipedia, lookup

Stray voltage wikipedia, lookup

Voltage optimisation wikipedia, lookup

Mercury-arc valve wikipedia, lookup

Tesla coil wikipedia, lookup

Rectiverter wikipedia, lookup

Switched-mode power supply wikipedia, lookup

Resonant inductive coupling wikipedia, lookup

Metadyne wikipedia, lookup

Opto-isolator wikipedia, lookup

History of electric power transmission wikipedia, lookup

Mains electricity wikipedia, lookup

Electrical wiring in the United Kingdom wikipedia, lookup

Alternating current wikipedia, lookup

Transformer wikipedia, lookup

Three-phase electric power wikipedia, lookup

Transcript
How to Calculate/Find the Rating of Transformer in kVA (Single Phase and
Three Phase)?
We know that, Transformer always rated in kVA. Below are the two simple formulas
to find the rating of Single phase and Three phase Transformers.
Find Rating of Single Phase Transformer
Rating of Single Phase Transformer:
P = V x I.
Rating of a single phase transformer in kVA
kVA= (V x I) / 1000
Rating of a Three Phase Transformer
Rating of a Three Phase Transformer:
P = √3. V x I
Rating of a Three phase transformer in kVA
kVA = (√3. V x I) /1000
But Wait, A question is raised here… Look at the General nameplate rating of a
100kVAtransformer.
Did you notice something????Anyway, I don’t care what is your answer
lets me try to explain.
Here is the rating of Transformer is 100kVA.
But Primary Voltages or High Voltages (H.V) is 11000 V = 11kV.
And Primary Current on High Voltage side is 5.25 Amperes.
Also Secondary voltages or Low Voltages (L.V) is 415 Volts
And Secondary Current (Current on Low voltages side) is 139.1 Amperes.
In simple words,
Transformer rating in kVA = 100 kVA
but
Primary Voltages = 11000 = 11kV
Primary Current = 5.25 A
Secondary Voltages = 415V
Secondary Current = 139.1 Amperes.
Now calculate for the rating of transformer according to
P=V x I (Primary voltage x primary current)
P = 11000V x 5.25A = 57,750 VA = 57.75kVA
Or P = V x I (Secondary voltages x Secondary Current)
P= 415V x 139.1A = 57,726 VA = 57.72kVA
Once again, we noticed that the rating of Transformer (on Nameplate) is 100kVA but
according to calculation…it comes about 57kVA…
The difference comes due to ignorance of that we used single phase formula instead
of three phase formula.
Now try with this formula
P = √3 x V x I
P=√3 Vx I (Primary voltage x primary current)
P =√3 x 11000V x 5.25A = 1.732 x 11000V x 5.25A = 100,025 VA = 100kVA
Or P = √3 x V x I (Secondary voltages x Secondary Current)
P= √3 x 415V x 139.1A = 1.732 x 415V x 139.1A= 99,985 VA = 99.98kVA
Consider the (next) following example.
Voltage (Line to line) = 208 V.
Current (Line Current) = 139 A
Now rating of the three phase transformer
P = √3 x V x I
P = √3 x 208 x 139A = 1.732 x 208 x 139
P = 50077 VA = 50kVA