By Greg Davis, International Sales & Product Support
When electrical safety calls, CBS ArcSafe answers — anytime and anywhere. In June, that “anywhere” was Alaska, where I traveled to the northernmost regions of our country to offer training and evaluation services to three clients.
My first stop was at the Red Dog Mine, located in a remote region of the Arctic. I spent one week training technicians on remote racking and remote switching solutions for ADVAC, HK, and DS circuit breakers, in addition to MCC buckets. Next, I went to the town of Sitka to perform a site evaluation of a transmission station downtown and two hydroelectric facilities in the area. Other than having to dodge a moose or two on the roadways, everything was going swimmingly.
Then, I landed at my last stop: the Valdez Marine Terminal of the Alyeska Pipeline, where 15 months earlier an arc flash occurred. The arc-flash incident, still fresh in people’s minds, resulted when an ABB/ITE 5HK breaker was being racked in. The latch mechanism had a problem: It did not stop in test and was racked all the way in. When it reached the connected position, the equipment that it ran was giving a “closed” command. So as soon as it hit the last position and the latch fell into place, the flashover and blast occurred. The worker operating the breaker suffered a concussion and a smoke inhalation injury.
I completed three days of training in Valdez. The first day was the site evaluation and unpacking of the equipment in the warehouse for the morning. In the afternoon, we did the classroom session and went over all the RSAs before moving them into the substations. The next morning, eight workers started off in the 4160 VAC gear with two versions of the HK/VHK using the RRS-4. In the afternoon, we went to the 15HK/VHK.
Everything went smoothly until the third day of training, which presented a few interesting challenges. Knowing that we were dealing with HK racking mechanisms, I went in-depth on the latch system. I covered bent latch rods, poor lubrication, and broken roll pins. As it turns out, we had a 15HK with a bent latch rod. Interestingly, the latch rod was bent to the right instead of the left. Don’t ask me how this happened. If I had not seen it for myself, I would not have believed it possible.
I told the class that a bent latch rod places stress on the roll pins and they would probably break. I also noted that metal shavings from the latch rod would fall in the racking mechanism. So, we racked it out, and guess what? The roll pins broke. When the roll pins break, the latch rod will go in and out like the slide on a trombone. This means the operator would not be able to control the latch system at all times in the racking process.
We pulled the breaker out of the cubicle and replaced the latch rod. We also checked the racking mechanism and racked it in and out twice while it was out of the cubicle to verify the replacement latch rod operated normally. We then placed the breaker back in service and racked it in and out several times.
After that, we went to the 4160 gear to rack in two 5HK breakers that needed to return to service, along with two K-Line breakers. I covered the characteristics of worn racking mechanisms in K-Line breakers. As luck would have it, the K-Lines had to have the racking mechanisms turned about 1.5 turns counter-clockwise to allow the door to drop. Several years ago, CBS ArcSafe did forensics for AEP on their small frame K-Line breakers. If a K-Line breaker has repeatedly been abused, then pins which are supposed to line up at the end of the racking process get bent and the breaker has to be racked out slightly to allow them to re-align so that the breaker can operate. Most people do not know that the K-Line racking mechanism and operating mechanism are tied together. The worst case we have seen is backing the breaker off 3.5 turns to get the shutter window to close when the racking tool is removed to allow the breaker to operate. There is no substitute for good maintenance.
On a personal note, because I was so far north during the summer solstice on June 21, I did not see the sun set. Experiencing 24 hours of straight sunshine was incredible. But all that sunlight presented a different kind of drama altogether: moose on the loose. You have to drive the Alaska roads with caution. If you crash into one of these beasts, it’s a tossup whether the moose or your car survives the impact.
This trip to Alaska made one thing clear: CBS ArcSafe’s remote racking and remote switching solutions solve a number of unexpected challenges and keep employees safe from arc-flash dangers.