Wiring on power pole

[Brad_C]

Originally Posted By: Shannow

True but there are still some (not many) single wire rural houses in my country.


Still quite a lot of SWER in rural WA.

 

[SHOZ]

Those gizmos are disconnects for the high voltage to the transformer. Around me they use to have fuses in the lines but now thy use self resetting circuit beakers. No need to send someone out to change fuse.

 

[turtlevette]

Originally Posted By: Shannow
Originally Posted By: ZeeOSix
Depends if it's a Wye or Delta AC configuration. Typically all three phases are never perfectly balanced, so they will use a Wye setup with a current carrying neutral that all 3 phases are tied to.

http://www.achrnews.com/articles/93448-more-delta-vs-wye-transformers

http://www.ecmag.com/section/your-business/wye-does-it-matter


True but there are still some (not many) single wire rural houses in my country.

Where I'm usually at, there's only three big conductors (and a massive earth grid)


All residential is single phase. Unless you have some massive place with waterfalls that need greater than 10hp pumps.

You may see 3 phase running down the street, but only one phase is tapped.

The transformer has one phase supply thru a fused cutout. Normally the gate will blow open and hang when the fuse is blown.

At the substation, relays with inverse time overcurrent curves and instantaneous functions provide feeder protection. Typically the relay will autoreclose the breaker 3 times. The first shot will miscoordinate with feeder fuses in the event the fault is temporary. Subsequent shots will force the fuse to isolate the permanent fault allowing the rest of the feeder to be restored. This technology is 75 years old.

New methods attempt to provide better reliability and safety by detecting arcing faults such as a conductor laying on the ground or a car sputtering yet not causing enough current draw to trip traditional over current devices.

 

[SHOZ]

Hate Wye three phase. No voltage showing up on one leg is very deceiving and potentially dangerous.

 

[BRZED]

Originally Posted By: SHOZ
Those gizmos are disconnects for the high voltage to the transformer. Around me they use to have fuses in the lines but now thy use self resetting circuit beakers. No need to send someone out to change fuse.


And are those similar looking devices right on top of the transformer also disconnects? Do you see any lightning arrestors? How do they differ in looks from a disconnect?

 

[SHOZ]

Here's my neighbors transformer. The red thing on top is an animal guard. The fuse looking thing is a disconnect,

Here's my transformer. Better view of the disconnect. We don't have lightning arresters here.

 

[exranger06]

This is a cutout:

The gray, pinecone-looking thing on the left is a porcelain insulator. It does not carry any electric current; it's just something for the metal brackets on the top and bottom to attach to. The cylinder on the right is a fuse holder. It's a hollow tube with a fuse inside. The fuse is basically a length of wire in the tube. The primary (high voltage) wire connects to the nut at the top. The electricity flows through that top metal bracket, through the fuse, and down to the lower bracket. The wire that connects to the transformer, or to a side-tap, or whatever other equipment, connects to the nut at the bottom.

If the fuse blows, you'll see it hanging down like this:

Note how the cutout on the left is open, and the one on the right is closed. Also note the circle hook at the top of the fuse holder. This is so a lineman can open the cutout manually as a way to disconnect and isolate lines or equipment using a hot stick (also shown in the second picture).

 

[BRZED]

Very interesting. Thank you! And I presume a lightning arrestor is a spark gap device that allowsm in case of a lightning strike, current to arc from a power carrying line to the ground.

 

[exranger06]

This is a transformer:

The pinecone-looking thing on the right is the high side bushing. This is what the primary wire connects to. The other pinecone-looking thing on the left is a lightning arrester. Note the wire connecting the bushing to the arrester on the top. Also note the wire connecting the bottom of the arrester to the tank of the transformer. The tank of the transformer is grounded. There is actually a wire that connects to the tank, runs down the pole, and connects to an 8 ft metal rod buried in the ground. Since the bottom of the arrester is connected to the tank, it too is grounded. The arrester is made out of a high-resistance material, and under normal conditions/voltages, there is no current flowing through it. If there were, the primary would have a dead short to ground, since it's connected to the top of the arrester. If there is an unusally high voltage event (like a lightning strike), that higher voltage overcomes the resistance of the arrester and the "excess" voltage goes right to ground, protecting the transformer.

 

[BRZED]

Thanks for taking the time.

 

[SHOZ]

Originally Posted By: BRZED
Very interesting. Thank you! And I presume a lightning arrestor is a spark gap device that allowsm in case of a lightning strike, current to arc from a power carrying line to the ground.
Most single phase pole wiring has the ground wire on top with he voltage wire beneath it. I don't know what good a lightning arrestor would have with miles of electrical lines. As mentioned before every pole has a ground wire.

 

[BRZED]

Infortunately, wikipedia does not elaborate on the usefulness of lightning arrestors.

 

[SHOZ]

My coop has whole hose lightning arrestor systems. I have a giant surge protector made by GE that is meant to be lightning arrest. It is wired across the two hot legs at the top of my panel.

 

[exranger06]

Originally Posted By: SHOZ
Originally Posted By: BRZED
Very interesting. Thank you! And I presume a lightning arrestor is a spark gap device that allowsm in case of a lightning strike, current to arc from a power carrying line to the ground.
Most single phase pole wiring has the ground wire on top with he voltage wire beneath it. I don't know what good a lightning arrestor would have with miles of electrical lines. As mentioned before every pole has a ground wire.

Not EVERY pole has a ground wire. Any pole with a piece of equipment on it (transformer, regulator, capacitor bank, etc) should have a ground wire. If there's no equipment, just wires, it doesn't need a ground wire. Although you need to have a ground every couple of poles or every several hundred feet or so (there's an exact number of feet that I don't remember). So if there's a line of poles going down the road and it's just wire and no equipment for a half mile, there will be some poles with ground wires, but not necessarily every one.

 

[SHOZ]

In my coop the new poles have the ground wire stapled too them. They all do have ground wires.

 

[Brad_C]

Originally Posted By: turtlevette

All residential is single phase. Unless you have some massive place with waterfalls that need greater than 10hp pumps.


There are loads of residences here with 3 phase.. like.. mine, and every house within a block either way of mine. Not everybody lives in a backwater.

My 3hp bore pump is 3 phase, as is my A/C compressor.

 

[Shannow]

not worth it

 

[turtlevette]

Originally Posted By: Brad_C
Originally Posted By: turtlevette

All residential is single phase. Unless you have some massive place with waterfalls that need greater than 10hp pumps.


There are loads of residences here with 3 phase.. like.. mine, and every house within a block either way of mine. Not everybody lives in a backwater.

My 3hp bore pump is 3 phase, as is my A/C compressor.


Really?

Low HP 3 ph motors are expensive and unnecessary. Most of he worlds residental is since phase. I suspect you don't really know what you have.

 

[MolaKule]

Originally Posted By: SHOZ
Originally Posted By: BRZED
So the shared neutral phase is grounded at (every?) pole? Did I get that right?


Yes. They run a copper wire down the pole.

That picture is two three phase circuits. The single and three phase feeders around me will always have a ground tied to the pole ground too.


What they use around here is "copper-clad" a steel wire with copper cladding:

http://www.southwire.com/support/copper-clad-steel-gets-theft-deterrence.htm

 

[turtlevette]

Originally Posted By: MolaKule
Originally Posted By: SHOZ
Originally Posted By: BRZED
So the shared neutral phase is grounded at (every?) pole? Did I get that right?


Yes. They run a copper wire down the pole.

That picture is two three phase circuits. The single and three phase feeders around me will always have a ground tied to the pole ground too.


What they use around here is "copper-clad" a steel wire with copper cladding:

http://www.southwire.com/support/copper-clad-steel-gets-theft-deterrence.htm


[censored]. Most everything in service is copper or aluminum.