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VT Error

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Cerkit

Electrical
Joined
Jan 18, 2016
Messages
100
Location
GB
Hi,

Does anyone know how I can calculate the Voltage Error and Phase error for a VT at a given output voltage if I know the error for other output voltages?

So in this instance a single phase VT has voltage error +0.8%,phase error 15minutes at output of 20VA with unity power factor. For an output of 110VA unity power factor the voltage error is -0.1%, phase error -3 minutes.

How can I calculate the the voltage and phase error at an output of 150VA unity power factor?

Thanks
 
You said "output voltages", but it sounds like you want to calculate the accuracy at a different burden (power output).

The accuracy of a VT (at a given voltage) moves linearly/proportionately with changes in burden (VA).

So you can plot the 2 points that you know and then extend the load line to 150VA.

This bulletin talks a bit about this. The ratings are in IEEE-speak, but the concept is the same.

 
Hi,

So if I plot two graphs, one Verror vs Burden and another Phase error vs Burden I can extrapolate, is this correct?

Thanks
 
No, please see the link I posted above. The graph is phase angle error and ratio error plotted at various burdens.
 
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