Couple of months ago, I’m sitting in my office, noting the dearth of disasters and the phone rings. That’s quite often the harbinger of bad news.
It was. One of my two offshore facilities is trying to swap generators. If you’re offshore, you make your own electricity. That station has three generators, two big ones that run off of natural gas, one smaller that uses diesel. We got lots of gas. It’s almost free. Diesel costs. Anyway, one of the gas-fueled units was out of service, and they were on the diesel unit and wanted to get off it and back onto the other gas unit.
And the breaker wouldn’t close. “Breaker” here, actually a circuit breaker, is a hundred pounds of steel, plastic and copper, rated to carry 1200 amps at 480 volts. Weighs a hundred pounds or so. Has the ability to be closed by external signals, such as the generator’s running and we want it to close so we can stop buying diesel, which ain’t cheap in the first place and it gets a lot more expensive when you have to put it on a boat and bring it twenty miles out in the Gulf.
Over the phone we discussed what the technician had seen. Generator running? Check. Voltage right? Check. Both generators in sync? Yeah, that’s a bit obscure for non-power people, but trust me, violating that has the possibility of sending some of your equipment back in time. But yes, the ‘sync’ light comes on. And the breaker doesn’t close.
Sounds like somebody’s gonna drive four hours, spend the night, catch a ‘copter out, first thing the next morning.
So that’s what I do. Just me and the chopper pilot for the thirty-minute trip out. Set down on the platform, watch the chopper leave, and I go meet my tech. We dive right in. A couple of clicks of a mouse on the station console and the generator’s running. We got into the electrical room and I survey the indicators. Yep! Looks good. I open the cabinet and find the little relay that is supposed to close the breaker. It has a clear case, so I watch it doing its thing. It’s trying.
Okay, I know the answer to this one. The tech watches a scope right out of a 1930 Frankenstein lab and when it nears the twelve o’clock position, he says “NOW!” and I punch the manual close button on the breaker. It slams shut, the two generators are now tied together, and we can shut the diesel unit down.
Now it’s time to make a call. The people who designed this offshore platform have made what I consider an error in judgement, using a low-voltage signal to close the breaker. That works fine when everything is new, but this thing is twenty years old and the little tap provided by low voltage isn’t sufficient to close a sticky twenty-year-old breaker. We make arrangements to get it refurbished.
That happened, the breaker has to go onshore by way of a boat, go to a shop in Houston, and come back. Couple of weeks ago the tech on the platform tried to install it in its hole and it wouldn’t go. He thought there was a problem. So I schedule another trip.
I was out there this morning. I looked at the breaker. The parts that are supposed to connect the breaker weren’t lubed. That can account for unusual forces, so i carefully and precisely applied synthetic grease with the end of my index finger. We stuck it into the hole and tried to get it to ratchet into its operating position. And it wouldn’t go.
“Gimme a flashlight!” I said.
A flashlight was supplied and I peered into the cabinet because I could see the fingers on the breaker where they contacted the corresponding stabs connected to the generator on one side and the power distribution bus on the other. And I started laughing.
The problem was obvious. The highly rated professionals who’d disassembled my breaker to refurbish it had put one set of fingers on incorrectly, rotated ninety degrees from where they needed to be. The breaker came back out of the hole, fifteen minutes with a tool set and things were the way they should be. The breaker went in the hole exactly as it was supposed to do.
Next problem. That big natural gas engine that’s supposed to run this generator? It won’t start. Turns over. Tech says if he tugs the control rod that feeds it gas, it runs, so it’s not the engine. This thing has a an electronic governor, and THAT thing needs twenty-four volts that appears to be missing. Tech thought that maybe the breaker needed to be installed because it actives some auxiliary switches. That’s a good guess and an easy try. Back in the control room, click the mouse. Engine turns over. Doesn’t start.
Back in the control cabinet. Still no 24 volts. Get out the drawings. Says ‘customer-supplied 20-40 volts DC’. Get more drawings. Shows a fuse I already traced out and checked, and then it stops. the voltage has to come from somewhere. He thinks it might be a control box out at the generator, so I let him open that up. We look. It ain’t there. While he’s putting things back together, I start looking.
‘Oh,look! Here’s a panel full of circuit breakers and the door says ’24 VDC’. Bingo! I open it, look at the legend, lo and behold, there’s one that says #1 Generator Switchgear. I turn it on, then check that governor. We got power. He comes back in, I show him that breaker panel, and then back in the control room, a couple of mouse clicks and from outside comes the throaty VAROOM! as that big engine fires up and runs.
Lunch was pretty good barbecue ribs, sausage, steak, baked beans, a freshly made potato salad and ‘nanner pudding with vanilla wafers and meringue topping.
Thirty minute trip back in the ‘copter to the onshore base, and then a four hour drive home.
Pretty good day.
