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Join Date: Jun 2011
Posts: 14

# Calculate/Measuring Zero Sequence Current in Tertiary Winding of Transformer

09/30/2017 7:11 AM

We have 135MVA Transformer, HV - Star , LV - star and inbetween Tertiary winding -Delta (didn't be connected to any load) configuration. We need to calculate or measure Zero sequence current that flows through Tertiary winding.

Please tell me how to calculate or measure Zero sequence current that flows through Tertiary winding.

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Guru

Join Date: Apr 2010
Posts: 5998
#1

### Re: Calculate/measuring Zero Sequence Current in Tertiary winding of Transformer

09/30/2017 11:30 AM

Perhaps this will help:

Transformer Modelling Guide

Active Contributor

Join Date: Sep 2017
Location: Russia, Moscow
Posts: 23
#2

### Re: Calculate/measuring Zero Sequence Current in Tertiary winding of Transformer

10/02/2017 2:45 AM

Delta are filter for Zero Sequence Current. Why is you need it?

Power-User

Join Date: Sep 2016
Location: SPAIN
Posts: 205
#3

### Re: Calculate/measuring Zero Sequence Current in Tertiary winding of Transformer

10/02/2017 3:01 AM

You could install a residual voltage relay, AKA zero sequence voltage/neutral displacement relay, such as "ABB SPAU 110 C".

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Join Date: Sep 2017
Location: Russia, Moscow
Posts: 23
#4

### Re: Calculate/measuring Zero Sequence Current in Tertiary winding of Transformer

10/02/2017 3:11 AM
Guru

Join Date: Dec 2010
Posts: 1263
#5

### Re: Calculate/Measuring Zero Sequence Current in Tertiary Winding of Transformer

10/02/2017 3:38 PM

Obvious first question - does tranfo terminal diagram plate show external terminals for tertiary windings? How arranged?

Does transfo specification have any data on tertiary windings, such as rated current, voltage and impedance? How do rated voltage & current for primary and secondary windings compare?

Usually, current in tertiary winding is due to single phase load on secondary windings & in proportion to it but tertiary winding will also carry third harmonic currents from the secondary, shunting them away from primary.

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