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Thanks for your reply! I saw that section as well but this is going to be outdoor and will definitely be exposed to sunshine/weather. I'm still struggling to locate any guidelines on this.

I've looked through the NEC but I can't seem to find anything that points to the allowable fill for outdoor precast cable trench. Does anyone know the applicable guide/section for this?

I've been searching for what the line-ground clearance for a transmission type structure within a substation fence over a drive path. I am having a difficult time finding a specific rule. We are using a transmission-type structure with phase-over-phase (lines attach vertically) attaching to an...

I had the opportunity to watch a 230 kV line switch closing to tie the 230 kV line to the new substation that was built for a 230 / 13 kV substation which was energized. I noticed that when the switch was closed, there was arcing as the switch was being closed. Is this arcing normal or is...

Typically, power transformers are paralleled because the load growth has exceeded the capacity of the existing transformer and the age of the transformer precludes scrapping or relocating them and purchasing a new larger one. With that said, is a LTC only necessary if the existing transformer...

So, basically, if the transformers have the same characteristics (voltage rating, impedance, X:R ratio, etc.) and placed on the same tap then a LTC is not required. Otherwise, circulating currents and unequal load sharing will result. Is this correct?

Is a load-tap-changer (LTC) required for all paralleled transformers? If so, why? If not, what are the circumstances that one will not be required?

We actually have a CT going to a relay but the relay is reading zero amps and zero degrees so we are thinking that a shorting screw was left in place somewhere. What we were wondering was if we took a ammeter if we could test the current near the CT to see if this was the case. The ammeter...

I have a bushing current transformer on a transmission circuit breaker. If I short the current transformer and ground it, does current still flow through the closed loop?

Does anyone know of any good learning references for relaying and controls for transmission substations?

Also, I am trying to think of the advantages and disadvantages of such schemes.

I am trying to learn about relaying and on one high-impedance bus differential scheme I noticed it utilizes current elements in the CT circuit. What is the purpose of this? I think one purpose is to detect breaker failure in the event one breaker fails to trip but what are the other uses?

What does "Shunt Trip Voltage" mean? I was assuming that it is referring to all three phases tripping simultaneously but I want to make sure. I found the following breaker but is says no for shunt trip voltage...

I am looking for a 3Ø 208VAC cabinet with a single 400A breaker that will need an auxiliary contact for the state of the breaker and will need to be NEMA 3R or 4. Has anyone used anything similar? I do not know what to look for as far as manufacturers and breaker types. Also, I have never...

Does anyone know of an article that explains exactly why aluminum and copper fittings should not be connected together and why bronze should be used to connect aluminum to copper?

Still looking...

I am looking for manufacturers of non-metallic fencing to be installed in a power substation around a Static Var Compensator (SVC). I have already received a quote from one and need another. Here is the one I found: www.amico-securityproducts.com/non-conductive-fence.htm Anyone know of another?