Operating challenge associated with of 34,500 volts?

[mbrooke]

What is the down sides in using 34.5kv overhead distribution? Saw this in a local POCO report:




I thought higher voltage was the way to go. Less loss, thinner wire. Seems like 12.47kv is better?

 

[electrofelon]

I know ferroresonance is more of a problem with 35kv class.

Another issue cited with higher voltage distribution is wider coverage per circuit thus more widespread outages from failures and tree damage.

 

[mbrooke]

I know ferroresonance is more of a problem with 35kv class.

Another issue cited with higher voltage distribution is wider coverage per circuit thus more widespread outages from failures and tree damage.

Could be the case.

Any idea of the cost of 35kv equipment vs 15kv equipment?

 

[electrofelon]

Could be the case.

Any idea of the cost of 35kv equipment vs 15kv equipment?

Funny you should ask, I have been meaning to start a thread asking the same question. I dont quite get the "longer lines thus more people out during an outage" argument against 35 KV class. It seems you could utilize the advantages of less current, less losses, smaller wire, less voltage regulators without taking the line to a wider area coverage over what 15KV would be. Perhaps the equipment is substantially more expensive? I have checked and clearances are not any different, but perhaps more tree trimming is prudent?

 

[electrofelon]

This is a good document:

http://www.idc-online.com/technical_references/pdfs/electrical_engineering/Primary_Distribution_Voltage_Levels.pdf

Although it says this which sounds lame:

"- Crews do not like working on higher-voltage distribution systems."

 

[mbrooke]

Funny you should ask, I have been meaning to start a thread asking the same question. I dont quite get the "longer lines thus more people out during an outage" argument against 35 KV class. It seems you could utilize the advantages of less current, less losses, smaller wire, less voltage regulators without taking the line to a wider area coverage over what 15KV would be. Perhaps the equipment is substantially more expensive? I have checked and clearances are not any different, but perhaps more tree trimming is prudent?

You know, I have the same questions are you lol. 35kv fascinates me. But I see POCOs that don't want to touch it.

 

[mbrooke]

This is a good document:

http://www.idc-online.com/technical_references/pdfs/electrical_engineering/Primary_Distribution_Voltage_Levels.pdf

Although it says this which sounds lame:

"- Crews do not like working on higher-voltage distribution systems."

Thanks

Some utilities would refer to this as subtransmission, others as distribution.

When making my drawings, I would call it "bulk distribution"

 

[Hv&Lv]

You know, I have the same questions are you lol. 35kv fascinates me. But I see POCOs that don't want to touch it.

Would you?
I mean physically touch it...
If it’s damp, it hurts...

 

[mbrooke]

Would you?
I mean physically touch it...
If it’s damp, it hurts...

I don't think you can bare hand 15kv. At least not in typical line work where you are changing stuff out. Standing on one wire with proper clearance and a mesh suit yes but why would you?

 

[Hv&Lv]

I don't think you can bare hand 15kv. At least not in typical line work where you are changing stuff out. Standing on one wire with proper clearance and a mesh suit yes but why would you?

I mean with rubber gloves. It still hurts under the right conditions.

And yes, if you can bare hand transmission, you can barehand 15kV. It’s just not done.

Gloving off the pole is going by the wayside also.

 

[mbrooke]

I mean with rubber gloves. It still hurts under the right conditions.

And yes, if you can bare hand transmission, you can barehand 15kV. It’s just not done.

Gloving off the pole is going by the wayside also.

How is 23kv? I've heard of 23kv tracking down hook sticks in pouring rain just enough that the linemen feel it.

I'm immensely debating 15 vs 25 vs 35kv like you wouldn't believe it.

 

[Hv&Lv]

How is 23kv? I've heard of 23kv tracking down hook sticks in pouring rain just enough that the linemen feel it.

I'm immensely debating 15 vs 25 vs 35kv like you wouldn't believe it.

15 kV can be done in damp conditions hot.
25 and 35 hurts when it’s damp or wet. Summer hot work starts to hurt also when everything’s wet and salty...if your sticks clean it won’t track that bad. That’s why they say clean them often..

 

[mbrooke]

15 kV can be done in damp conditions hot.
25 and 35 hurts when it’s damp or wet. Summer hot work starts to hurt also when everything’s wet and salty...if your sticks clean it won’t track that bad. That’s why they say clean them often..

How much more does 35kv hurt over 25kv?

I know national grid avoids 25 and 35kv as much as possible.

 

[mbrooke]

I mean with rubber gloves. It still hurts under the right conditions.

And yes, if you can bare hand transmission, you can barehand 15kV. It’s just not done.

Gloving off the pole is going by the wayside also.

One thing I don't like about 35kv is ferroresonance. I like everything in delta. These guys are either suicidal, or know something the rest of us do not:







So how do they even switch this on?

 

[Hv&Lv]

How much more does 35kv hurt over 25kv?

I know national grid avoids 25 and 35kv as much as possible.

It’s all relative...
Can I tell the difference between 25 and 35? Probably not.everything dry, no sweat in gloves, no problem.. it just kind of vibrates in your hand.

 

[Hv&Lv]

One thing I don't like about 35kv is ferroresonance. I like everything in delta. These guys are either suicidal, or know something the rest of us do not:


View attachment 2552020


View attachment 2552021

So how do they even switch this on?

Fuses on pole

 

[mbrooke]

Fuses on pole

Close one, close the other... about to close the third... BBBRRRRRRDRRRRRRRDRRRRRRRDRRRRRRRRDRRRRRRRRDRRRRRRR...

 

[mbrooke]

It’s all relative...
Can I tell the difference between 25 and 35? Probably not.everything dry, no sweat in gloves, no problem.. it just kind of vibrates in your hand.

Well...

 

[Hv&Lv]

It’s not that bad.. smaller step down substation transformers are done the same way.

You want to put 200Es on a station XF. Same thing...

 

[mbrooke]

It’s not that bad.. smaller step down substation transformers are done the same way.

You want to put 200Es on a station XF. Same thing...

Then why do so many POCOs want a wye primary? T and delta connected 15kv pigs are everywhere for sale on the net, but 25 and 35kv are exclusively wye.

In my mind 200Es on a station transformer will not be much of a risk due to customer load dampening ferro out. Just drop the unit via some SF6 load breaks.