Entertaining couple of days at work.

[J Sigmo]

Tuesday: Lightning strikes the power lines on a pole right at the edge of our water plant's property. This takes out one fuse and one lightning arrestor at the pole, cutting one phase of the high voltage feeding the primaries of the transformer banks that feed both the plant and our "settled water pumphouse".

This also killed both of the loop detectors for our automatic gate and blew a surge suppressor on one of my boards that protect our PLC system and data acquisition system on a buried (4-20mA current loop) line from an electromagnetic flow meter in a pit a few hundred feet from the plant.

All of this was easy to fix or live without. The power company came out and replaced the blown cut-out on the pole, but did not replace the fried lightning arrestor.

With power restored, we got the plant back running, and started "making" drinking water for the town again. Fine.

Fast forward about 24 hours to the following afternoon. A small girl and her grandpa are flying a kite.

See where this is going?

The kite comes down right on the very place where lightning had hit the power line the day before.

Guess what? Kite frames are now made with carbon fiber struts!

Big flash, loud noise, excitement, and fun for all!

These tiny, thin, carbon fiber struts about 3/16" in diameter are blown into fluffy things that look about like a horse's tail in diameter. They hang across all three phases and intermittently short the phases as the breeze moves them near enough.

The vegetation below the power pole catches on fire. The fire department and police show up. Everyone has a fun time.

We call the power company, and the same guy from the day before comes out and pulls three fuses down the street at a ground box to kill power to our pole so he can get up there and safely remove the carbon fiber from the wires.

He then replaces the blown cutout, and, at our suggestion, also the surge suppressor.

He then replaces the fuses down the street, and everything looks OK, so he leaves.

But our phase monitors keep tripping intermittently, so we check all three phases on the 480V side of things in the plant. Sure enough, one phase is intermittent, and shows widely varying voltage.

We call the power co again, but the first guy is off for the evening, so they send out another guy.

At first, he says the power reads within their tolerances, and prepares to leave. But we insist that it's intermittent, and that our readings show one phase to be bad.

I suggest that he check where the fuses were pulled and replaced down the street because it appears that one fuse is not making good contact. He scoffs, but checks it out anyhow.

He comes back about an hour later and says when he approached the box, he could hear arcing and smell it. He said the Blue light coming out of the box was pretty spectacular.

He went further down the line to de-energize that box, and replaced the now-fried fuse. He brought it with him, and it was pretty impressive!

At this point, the power was good. But the "brownout" effect on that particular phase caused a switching power supply in a fancy controller for a pair of turbidimeters (on-line water quality instruments) to roast. Lots of bulging electrolytic caps in that baby!

I replaced that controller with a spare I had repaired a few years ago, and by midnight that night, we had the plant running once again.

Wish us luck for the future!

 

[TonyR]

After all that I have one question:

Kids fly kites these days?

 

[alastairstevenson]

Wish us luck for the future!

Wow! That sounds like you've used up a years worth of incidents just in a couple of days.

 

[J Sigmo]

Well, I'm guessing grandpa was showing the little girl how to fly a kite. I hope the incident didn't freak her out too bad!

It does seem like we got about ten years' worth of power line incidents in within a 24 hour window.

Lightning is spooky, but the kite thing was actually very interesting.

 

[pinko]

Hectic few days there fore sure, you made it alive.. also, making mental note to avoid kites with super conductive carbon fibre frames...lol

 

[TonyR]

@J Sigmo ,
Your experience convincing a power co. employee to check something and his "scoffing" reminds me of this:

Three years ago a gray squirrel chewed the ACSR (aluminum conductor steel reinforced) messenger on the overhead electrical service drop (which is also the neutral for a 120/240 volt, split-phase, 3-wire residence) going to my mom-in-laws house. Nothing in the house that ran on 120VAC would work, only the 240VAC water heater, clothes dryer and stove would work, as they don't need a neutral.

According to his story, the power co. employee that responded to her call glanced at the meter FROM THE TRUCK, saw that it was running (digital with several 8's in the LCD running its 7 segments sequentially) and drove off, didn't even get put of the truck, reported back "problem on customer side".

I had to convince them the next day that a 240V meter will run with no neutral because it measures across the 2 hot legs and a neutral was missing coming from the transformer. I also suggested they get out their #$@# truck next time and make a few checks with a simple tester.

The best part of this was that the area manager of these guys was a WOMAN and when I told her my WIFE called and they ignored her and then her 78 year old MOTHER called them they ignored her as well but when a MAN drove 42 miles, walked into their local office and complained that they jumped right on it. I told them they left an elderly women alone in the dark all night with no lights because of the missing neutral. She called me back later after they spliced the broken neutral on the overhead feed and apologized and said she was embarrassed that a customer had to teach her field tech how his own power meter worked. She also related that she had spoken to both her guys regarding procedures...I'll bet she did, too!

 

[J Sigmo]

@TonyR That sounds about right! I've seen this sort of thing from both sides over the years.

A missing neutral is a potentially very bad thing. Unless the loads on both 120 legs are balanced (which would be very unlikely at any given point in time), you can end up with over voltage on one leg, and under voltage on the other.

A guy I worked with back in the late '70s and early '80s had one of those Snap On screwdrivers with the magnetic shaft and interchangeable bits. The shaft was still straight and strong, but you could see that a large area of it had been molten at one time.

I asked him what had happened to it. He told me that years before, the lights in his house were getting brighter on one 120V leg and dimmer on the other, so he knew he had a bad neutral connection.

So he went outside and pulled the meter from the base and the used that screwdriver to tighten the connection for the neutral feed from the pole. His hand slipped.

He said the flash blinded him for most of a day, and he had a sunburn on his face, hand, and arm.

He always carried and used that screwdriver to constantly remind him not to be an idiot! He's a good guy, by the way. One of the people at that business from whom I learned a lot!

I understand that service people who work in a particular field end up dealing with a lot of customers who truly know very little about a subject. So they do develop a healthy disregard for the "troubleshooting advice" from consumers. And that's not an entirely bad thing because a customer can lead you down the garden path and waste a lot of your time troubleshooting something.

But often, the customer's observations can be very informative, and sometimes, the customer may actually have more experience and expertise than you do, and can save you some serious time.

There's no way for a technician to know how knowledgeable any given customer may be until they get to know them. For folks like us, who may have useful information, it can be frustrating dealing with service people who haven't yet learned that some of their customers actually do have some experience and expertise.

But that experience of yours was downright rude, lazy, and dismissive. I'll bet the manager did have some choice words for those folks!

 

[tangent]

Hardly compares, but I reported a broken insulator to the power company last week and they sent a crew the next day to fix it. In the process of fixing this pole they managed to take out the phone lines for a thousand people... oops.

High winds a few days later started a power line induce fire about 1/2 mile away, but at least there weren't two fires.

 

[TonyR]

More info regarding my post #7 on Wed. 7/24 :

I posted this video somewhere else on IPCT back in Feb. of this year when I think the topic was rodents (squirrels, gophers, rats, etc.) and what they could do to conductors, cables, etc.

Because the power company's neutral is bonded to the driven earth ground ONLY in the house's service panel, my mom-in-law would have had some return (albeit not correct) for the 120VAC lighting IF other things had NOT failed. BTW, her house was built in 1911 so that's a big "IF".

The cable TV installer tied their coax's collar to the house's earth ground as they do and they also do the same thing to the other end of the coax back at the power pole; that same point is tied to a bare copper which runs down that power pole to a ground rod.

Because the cable company's clamp was already LOOSE, when the squirrel chewed the neutral coming from the power company into 2 pieces, AND her house's driven ground rod at the service panel is questionable, the return for the house's 120VAC devices became the cable company's outside (shield) of their coax!

Note how the loose clamp caused the insulation on the green grounding conductor to melt due to voltage drop across that resistance ( Ohm's Law ); the same can be said for the red ring on the closest cable co. coax.....which is why just a day or 2 before the cable co. tech knocked on her door and told her he got shocked up on that pole when was disconnecting the cable that fed her house (she had just made the switch to satellite).

Ah HA...it all comes into focus now. She didn't tell me that when it happened 2 days before...instead she tells me that little factoid when I come 2 days later to look at why her lights (and all 120VAC devices) are flickering / out.