Open and short circuit test of transformer

1. Open Circuit (No Load) and
Short Circuit Test
by:
Dr Sunil Singh
Associate Professor, EED
GB Pant University of Ag & Tech Pantnagar
by Prof Sunil Singh (visit on YouTube)

2. Open circuit (no load) and Short circuit test
 Why ?
 To calculate equivalent circuit parameters (Re, Xe, and Rc, Xm).
 To measure core loss at rated voltage and copper loss at full load.
 To calculate efficiency.
 To calculate voltage regulation.
 To calculate the turns ratio
by Prof Sunil Singh (visit on YouTube)

3. Open Circuit or no load Test
 Procedure
 A, V, W is connected on
LV side : why ?
 HV side is left open or Connect a voltmeter
 Apply the rated voltage on primary (LV) side
 Take the reading of voltmeter, ammeter and
wattmeter.
by Prof Sunil Singh (visit on YouTube)

4. Calculation of shunt branch parameters
 Let at rated voltage the reading of
 Voltmeter V0 (rated voltage)
 Wattmeter P0 (core loss at rated voltage)
 Ammeter I0 (no load or exciting current,
3 to 5%)
 P0 = V0 I0 cos ϕ0
cos ϕ0 = V0 I0 / P0
 Ic = I0 cos ϕ0
 Im = I0 sin ϕ0
 Rc =V0 / Ic
 Xm =V0 / Im
by Prof Sunil Singh (visit on YouTube)

5. Short Circuit Test
 Procedure
 Connect A, V, and W on
HV side : why ?
 Short circuit the LV side
 Adjust the voltage till full load primary current
flows. (KVA/ HV rated voltage)
 Take the reading of voltmeter, ammeter and
wattmeter.
by Prof Sunil Singh (visit on YouTube)

6. Calculation of series branch parameters
 Let the reading of A,V, and W at full load
current
 Voltmeter, Vsc ( 5 to 12 % voltage)
 Wattmeter, Psc (Full load Copper loss)
 Ammeter, Isc (full load current)
 ZeH = Vsc /Isc
 reH = Psc / Isc
2
 𝑋 𝑒𝐻 = (𝑍𝑒𝐻2 −reH
2 )
 X1 = X2 = ½ XeH
 r1 = r2 =½ reH
by Prof Sunil Singh (visit on YouTube)

7. by Prof Sunil Singh (visit on YouTube)

8. by Prof Sunil Singh (visit on YouTube)

9. Thank You
For your attention
To Watch the YouTube video
Please visit my channel Prof Sunil Singh
Link of one video is being given, from where you can to
channel. Search the topic followed by my name.
https://youtu.be/RMp3SUrfL5M
by Prof Sunil Singh (visit on YouTube)