Why CT secondary should not Open condition- Live Test Demo

Why CT secondary should not Open condition-:

Basically CT nothing but current transformer. It works like a step up transformer.

As the diagram said

V1= primary voltage of the current transformer


V2= Secondary voltage of the current transformer

I1= Primary current

I2= Secondary current

L= length of the conductor (main CT secondary core length)

A = cross section of the conductor

CT ratio: 4000/1 amps.

Any type of load inductive or resistive

 


The Transformer equation:

V1 x I1 =V2 x I2

Generated EMF in Sec side if it’s in open

  • V2= V1 x I1/I2————————————–1
  • Consider V1=pL x I1 /A
  • HERE p=RESISTIVIE OF THE CONDUCTOR
  • L= LENGTH OF THE CONDUCTOR
  • A= CROSS SECTION OF THE CONDUCTOR
  • Approximately p=1.72 x 10-8Ω.m.
  • Length= 1 mtr
  • Area= 180 Sqmm
  • V1=1.72 x 10-8 x 1×4000/180 x 10^-6
  • V1=0.382 V
  • Put V1 in Equ 1
  • V2= 0.382 x 4000/1
  • V2=1528V
  • CT secondary Voltage goes very high when it is in open condition. there is a chance of flash over or insulation failure.

      To avoid that it must be kept short .

Video Tutorial in English:


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