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Just watched the Oliver Stone film. Impressive treatment of the subject. Available pay-per view. I recommend it.

How do you handle the mutual coupling? Ignore it. Carefully model the distribution circuit(s) and mutual(s) in your fault program. Model just the distribution neutral in your fault program. Measure the line impedances including the mutual coupling with test equipment. Use actual fault data to...

A rare thunder windstorm caused both 230 kV lines feeding a transco substation to trip open, causing a big outage. Transco found and removed a tree in one of the lines and stood by to reenergize. The wind had died down, but the lightning continued. Transco evidently has a strict policy of not...

All, I'm looking to specify an 8 MW transformer for connecting two four wire distribution systems that are in phase. This can be accomplished with an auto-connection, but will this be the most cost effective way to go? I know that's commonly the case at transmission voltages, but unsure at the...

Situation: Utility customer meter is occasionally registering reverse power flow and PV panels are visible on the property. The customer has not gone through the net-metering approval process, so the utility has no record of the installation or knowledge if NRTL products were used, what...

The NEC excludes equipment under the exclusive control of electric utilities used for communication. The NESC speaks of overhead and underground communication line installation, but I fail to see mention of any installation requirement for the indoor equipment installation at a microwave site...

Following a recent failure (that preceded last week's ice storm), I've been looking into these things. [ol 1] They reduce the allowable tension to 60% of that of an un-spliced conductor. They need at least 15% of the conductor breaking strength to function. [/ol] Does this 15 to 60% window seem...

This is related to my other question. I was incorrect on the voltage, neighbor has 24.9 kV, ours is 12.47. Both are grounded wye systems feeding unbalanced loads. The 60 degree phase shift can be accommodated with a Yy6 connection by choosing the proper bushings. The transformer size is 3000...

The situation: Neighboring utility uses the the same voltage wye grounded system as we do, but is shifted from us by 60 degrees. In order to allow a closed transition transfer, our neighbor is proposing to use a delta/zig-zag phase shifting transformer. I know zig-zags are used for grounding...

Says to add two bells for dead-ends, but fails to indicate why. It goes on to speak of leakage distance, explaining the horizontal strings wash better and are less susceptible to contamination leakage, so this does explain the difference. Does anyone know why to add bells at dead-ends, and does...

A bushing on a '74 Westinghouse faulted recently. The transformer is fed from a 69kV underground line. An oil filled compartment attached to the transformer houses the cable terminations and the exterior portions of the oil to oil bushings. I cannot find a record of any pf testing on the...

An office building served three phase through a wye/wye service transformer has a standby generator and UPS system. When service is lost, the UPS keeps the critical loads up while the generator cranks and the transfer takes place. Over the weekend, a primary phase was lost. The UPS kept the...

thread238-474408 It happened again. Watch these manufacturers.

https://res.cloudinary.com/engineering-com/image/upload/v1671143998/tips/DOC005_cvrzwk.pdf Can anyone help me understand the purpose of the 84X/TDO normally closed contact and the diode on the right side of this drawing? The two resistors brake the motor once it gets on step, but the midpoint...

A radial line feeds an industrial site that has generation partially offsetting their load. Synchronizing equipment is at the generator breaker only. It is decided the sourcing substation should send a transfer-trip signal to the generator breaker when conditions dictate. Would you source this...

We have a single substation LTC equipped transformer that has an internal LTC VT. Is anyone familiar with these VTs? Is there simply an extra lead on the bottom end of the X1 and X0 bushing? Is the VT mounted on top of the core? Thanks.

My group installs these in order to control touch potential. It's been suggested we are alone in this endeavor. Anyone else doing this?

We've used online oil filtration systems for our resistive LTCs with good experience. Lately, it's been suggested that we extend maintenance intervals on our older reactive LTCs by retrofitting filtration. My concern is the filters will load up so quickly they will continue to be high...

Anyone here deal with or have familiarity with the code?

I'm attempting to delay program execution in a user logic program in an SEL RTAC. This is what I came up with: VAR Pause:TON; END VAR //Program Pause Pause(IN:=TRUE, PT:=T#100MS); //start timer WHILE NOT(Pause.Q) //loop until timer expires DO...