Cut-Out Arrestor Combination on Primary Feed-Through

[eeee]

I was curious if the arrestor that is normally connected to the cut-out on the primary feed-through which traverses from the 12,460 volt primary overhead line down the utility pole riser to go underground is a lighting arrestor or a surge arrrestor (otherwised known as a spike arrestor)?

This arrestor is seen in-line with my cutout, located between the cut-out and the riser on the utility pole. The cut-out is located between the primary 12,460 volt overhead and the arrestor.

Some folks keep indicating I am installing a lighting arrestor. That confuses me since a lighting arrestor takes a parallel path to ground I thought and is not in line with the circuit.

I have a drawing which indicates it is called a polymer arrestor. I assume this means ceramic polymer (need to go back and check my chemistry), but does not tell me if it is for lighting arresting or voltage spike (otherwise called surge) arresting??

 

[eeee]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

Actually a lighting arrestor should be a circuit by itself and not take a parallel or in-line path, but rather be its own circuit to ground in oder to protect active circuits from lighting I would think.

So it must be a surge arrestor I would think?

 

[bphgravity]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

I wish I knew what you are talking about because it sounds really cool, but I am only familiar with equipment after the service point.

Perhaps one of the utility guys or enigneers can step in on this one.

 

[eeee]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

I just looked at it again and interfaced with an inspector. It appears the surge arrestor must be located above the cut-out. A surge arrestor is brown in color since it is ceramic. The white ridged system located above the cable comming out of the top of the riser on the utility pole, which traverses down the conduit (that I saw) is a termination system (note that it can not be an arrestor since it is whiteor off-white in color) used to terminate the overhead cable (via the skinny stinger comming off of the cut-out) to the fat black cable which traverses down the riser to go underground.

Most of my facilities do not have a surge arrestor located above the cut-out (but this is a feasible design if you think you absolutely need it), although I did see a facility with a pin insulator in-line with the cut-out and a lighting arrestor in a parallel path to ground connecting just above the pin insulator. I suppose the lighting arrestor would have a high enough resistance not to take current away from the primary destined for the transformer, only in case of a high voltage lighting strike.

For the responder that just wrote, a cut-out is a device usually located above the utility pole that can be hit with an electic stick from electricians sitting high above in a lift truck bucket to cut off the electricity from the primary ovehead in order to work on the pad mounted transformers below.

A ceramic surge arrestor is sometimes placed above the cut-out to bleed off voltage spikes that last more than one cycle I would assume simplistically put.

 

[bob]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

For the responder that just wrote, a cut-out is a device usually located above the utility pole that can be hit with an electic stick from electricians sitting high above in a lift truck bucket to cut off the electricity from the primary ovehead in order to work on the pad mounted transformers below.

A cutout is a device that holds a system fuse. It may be fused for 1 transformer or it may be fuse for several transformers. It can be used to disconnect the primary system from the cable by using a hot stick to open it.
Most utility arrestors are for lightning surges.
The arrestor is connected to the system primay conductor and to a path to ground. You generally have an arrestor mounted on each riser pole. The arrestor has an arc gap the will discharge when a lightning surge exceeds the gap voltage requirements.

 

[bdarnell]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

Originally posted by eeee:
The white ridged system located above the cable comming out of the top of the riser on the utility pole, which traverses down the conduit (that I saw) is a termination system

Typically referred to as a "pothead" in utility-speak.

 

[jim dungar]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

Ceramic devices may be any color. Please do not make guesses about equipment (function or voltage class) simply based on color.

Many years ago the primary color of electrical ceramic was changed from brown to gray. Brown may still be customed ordered but it is becoming rare.

 

[jtester]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

I think Brad is correct, the device around your ug cable is a terminator, not an arrester.

I worked for utilities for 18 years and have consulted as a PE for 20 more, and have never installed any type of an arrester in series with a phase wire in a distribution system.

There are gapped silicon dioxide arresters, the old ones, or more modern nongapped metal oxide varistor type arresters, but both are in parallel with the cable not in series.

Jim T

 

[charlie]

Re: Cut-Out Arrestor Combination on Primary Feed-Through

We know that a terminator is for terminating cable and a pothead is ceramic for terminations and is filled with a potting compound. Potheads are rarely used anymore since we use almost exclusively terminators.

For medium voltage applications, we use lightning arresters and they are connected to the phase wire with a short piece of wire and another short piece of wire to the grounding system on the pole from the bottom of the lightning arrester.