4160v primary single phase transformer

[jackman435]

The 3 transformers we are installing are single phase. The primary feeder is 3 ph. 4160/2400 gr Y . Each transformer has an H1 and H2 bushing. H1 is going to be A, B, or C phase respectfully. Is H2 on each transformer the neutral? Does the neutral get terminated with the same type of load break as the phase wire?

 

[kwired]

The 3 transformers we are installing are single phase. The primary feeder is 3 ph. 4160/2400 gr Y . Each transformer has an H1 and H2 bushing. H1 is going to be A, B, or C phase respectfully. Is H2 on each transformer the neutral? Does the neutral get terminated with the same type of load break as the phase wire?

Is transformer primary rated voltage 2400 or 4160? If you connect to neutral you are only applying 2400, that will be a problem if it is looking for 4160.

 

[Bugman1400]

If it has an H1 & H2 bushing, my guess is that it is rated to be connected 4160 L-L in delta config on the high side. However, you could connect the H2 to ground which would make the high side 2400 L-N. It is not typical to connect the high side as a G-wye since that would supply ground fault current to a fault on the primary side and may confuse protection relays. Typically, the xfmr will be connected as a delta 4160 L-L on the high side.

What's the ratio or the X wdg rating?

 

[kwired]

If it has an H1 & H2 bushing, my guess is that it is rated to be connected 4160 L-L in delta config on the high side. However, you could connect the H2 to ground which would make the high side 2400 L-N. It is not typical to connect the high side as a G-wye since that would supply ground fault current to a fault on the primary side and may confuse protection relays. Typically, the xfmr will be connected as a delta 4160 L-L on the high side.

What's the ratio or the X wdg rating?

How do you connect a single phase transformer in delta configuration?





BTW I do understand you can connect two or three single phase transformers in a delta configuration, or you can connect just one as a single phase system.

I also agree if it has two bushings it is likely intended to be connected 4160 L-L, but one should check nameplate rating regardless.

 

[templdl]

The 3 transformers we are installing are single phase. The primary feeder is 3 ph. 4160/2400 gr Y . Each transformer has an H1 and H2 bushing. H1 is going to be A, B, or C phase respectfully. Is H2 on each transformer the neutral? Does the neutral get terminated with the same type of load break as the phase wire?

4160 is nothing to screw around with. What concerns me is if you have previous experience with work with medium voltage which is a whole different ballgame than working with voltages up to 600v. Do you intend to do the install yourself or are you just curious?

 

[Bugman1400]

How do you connect a single phase transformer in delta configuration?





BTW I do understand you can connect two or three single phase transformers in a delta configuration, or you can connect just one as a single phase system.

I also agree if it has two bushings it is likely intended to be connected 4160 L-L, but one should check nameplate rating regardless.

The OP said he had 3 single-phase xfmrs so, wouldn't you connect PhA_H2 to PhB_H1 and then PhB_H2 to PhC_H1 and etc? Since he said 3 xfmrs, I assumed it was a closed delta config.

 

[kwired]

The OP said he had 3 single-phase xfmrs so, wouldn't you connect PhA_H2 to PhB_H1 and then PhB_H2 to PhC_H1 and etc? Since he said 3 xfmrs, I assumed it was a closed delta config.

OP did say he had three transformers, did not say if he was building a three phase bank out of them. Could be supplying three single phase separately derived systems as well.

OP also did not answer some questions - in particular nameplate voltage. He stated supply is 4160/2400, then asks if neutral connects to H2. Seems to me the answer to this question alone completely depends on rated input voltage. If it is 4160 then you do not connect H2 to the neutral or you are only supplying that 4160 volt coil with 2400 volts.

 

[Tony S]

If the OP can?t say if either the left or right sections in this drawing are correct then he should walk away from this job.

Sorry if this sounds harsh, but HV isn?t a game for the unwary to play.

 

[kwired]

If the OP can?t say if either the left or right sections in this drawing are correct then he should walk away from this job.

Sorry if this sounds harsh, but HV isn?t a game for the unwary to play.

And answers to some of my questions will be a big factor in determining which one is right, both are right, but each has different conditions that apply.

 

[Bugman1400]

OP did say he had three transformers, did not say if he was building a three phase bank out of them. Could be supplying three single phase separately derived systems as well.

OP also did not answer some questions - in particular nameplate voltage. He stated supply is 4160/2400, then asks if neutral connects to H2. Seems to me the answer to this question alone completely depends on rated input voltage. If it is 4160 then you do not connect H2 to the neutral or you are only supplying that 4160 volt coil with 2400 volts.

Good point....I only assumed a 3PH load and not 3 1PH loads.

 

[jackman435]

We have extended an existing aerial 4160/2400 gr y. circuit - 3 acsr phase wires and 1 acsr neutral. This will be feed the primary side of 4 single phase transformers. The approved drawings have come back with H1 & H2 bushings indicated. Based on the voltage of the primary feeder, that would require 2 legs (A & B for example) to be terminated on the 2 bushings. That would be delta 4160 L - L. These are my questions:

1) Is the primary neutral required to carry back the unbalanced current? 2) Is a grounding conductor required to complete a fault current path back to the source? 3) Should the transformers be protected against voltage surges with a surge protector? Should each phase have it's own surge protector?

 

[Bugman1400]

1.) No neutral is required. It is typical for 3PH distribution xfmrs to be connected delta on the primary side. But, there are many sites that have a g-wye/g-wye application. If there is an alternate source or you plan to parallel sources, make sure both are in phase with each other.
2.) You'll need the appropriate grounds for the xfmrs.
3.) Yes. They should be on each phase and be rated some percentage above L-N and should be coordinated with nearby surge arrestors. IOW, if you install an arrestor that is a lower rating than the others, yours would conduct first and could possibly burn out quickly. If all the arrestors are at the same rating then the surge is clamped among the arrestors evenly.

 

[kwired]

We have extended an existing aerial 4160/2400 gr y. circuit - 3 acsr phase wires and 1 acsr neutral. This will be feed the primary side of 4 single phase transformers. The approved drawings have come back with H1 & H2 bushings indicated. Based on the voltage of the primary feeder, that would require 2 legs (A & B for example) to be terminated on the 2 bushings. That would be delta 4160 L - L. These are my questions:

1) Is the primary neutral required to carry back the unbalanced current? 2) Is a grounding conductor required to complete a fault current path back to the source? 3) Should the transformers be protected against voltage surges with a surge protector? Should each phase have it's own surge protector?

Again I ask what is the voltage rating of the primary side of the transformer(s)?
If they are 4160 volt the only way you can supply that from what you have for a source is two phase conductors.
If they are 2400 volt the only way you can supply that from your source is a phase and a neutral conductor - even if both inputs are via an insulated bushing the transformer still needs proper input voltage or you will release the smoke from the winding insulation.

If both H1 and H2 are via insulated bushings and you need to use neutral for one of them you may need to provide your own bonding to the transformer case. Exactly how this may need to be done will depend on if this is NEC or NESC application.