Ferroresonnance in earthed singe phase supply.

[prc]

Will it feasible to occur ferroresonnace in earthed single phase suppy? To be specific, in 27.5 kV traction supply where return path is rail.Any experience or references?

 

[davidbeach]

I wouldn't think so... All the explanations I've seen involve 3-phase transformers; whether that's because it requires 3-phases or if it's because that's what the target audience deal with I'm not sure.

 

[ssantoshr]

Ferroresonance occurring on single phase are very rare but I have read some cases where the ferroresonance situation occurred on single phase transformer (240/120V). The transformer was in series resonance with the cable capacitance. Ferroresonance can occur in a series inductive (transformer) - capacitive (cable) circuit.

however I never came across your scenario but i dont think there would be any problem.

 

[busbar]

A de facto document is ANSI standard IEEE C57.105-1978 IEEE Guide for Application of Transformer Connections in Three-Phase Distribution Systems §7, that be of some help.

 

[magoo2]

I tend to agree with the opinion that ferroresonance doesn't occur with single-phase circuits. After all, one of the key ingredients for it to occur is single-phase switching on three-phase circuits and getting an open phase condition with a three phase transformer or bank of single-phase transformers. You can find a lot of IEEE papers on the subject by Hopkinson, Dave Smith and more recently by Reigh Walling.

For the single-phase energization resulting in overvoltages, it is possible to have a tuned circuit. This resonance is not associated with ferroresonance and it's pretty rare. This is not a play on words; this condition is essentially different than ferroresonance.

 

[prc]

May be resonnace or ferroresonance, but it is seen 25 kV PTs suddenly burst during light load/ switching in operation.2nd and 8 th harmonics are also seen in the 25 kV system.What does it mean? Any sympathetic magnetising inrush current? If ferroresonance, we can put resistor across the secondray of PT. What are the mitigation measures for resonance?

 

[ssantoshr]

Here is the paper that has some case studies on ferroresonance

 

[jghrist]

Ferroresonance depends on getting the transformer winding in series with cable capacitance. This won't happen with a Ø-n connected transformer, but I guess it could with a Ø-Ø connected single phase transformer.