Welder Power

[johnc]

I've been using my Precision TIG 275 for a ferw months now and I wasn't happy with its performance when the amps were turned up on AC welding big aluminum. I'd have the setting on, say 225, and with my foot to the floor I would only get about 185 amps. Plus I would see the power sag a bit while running long beads and occaisionally the 85 amp breaker would trip, shutting the machine off and smoking a tungsten.

 

A couple weeks ago, while welding a bunch of aluminum, half the shop lost power completely and nothing powered by 220 would work. I checked the panel in my shop and one of the three phase leads was only delviering 8V, instead of the 120V the other two showed. I traced it back to the main power supply for the building and found a completely melted lead going to my meter:

 

 

This complex was built in 1976 when aluminum wiring was allowed. Over time, through galvanic action, where the aluminum wire connects to brass, steel, or copper connections, corrosion develops and the resistance increases. The landlords replaced the failed wire with a new copper one and cleaned all the other aluminum wire connections.

 

Now my TIG welder delivers all the amps I ask of it.

[Ledphoot]

I had a similar problem in an old shop I rented for awhile. I had problems keeping an accurate setting on my MIG. I thought it was my unit until a buddy was digging around behind some parts and noticed smoke in little puffs coming from my breaker box. Turned out some of the lugs on the main service cable were loose. I tightened those with a big allen wrench and never had another problem..

[Pop N Wood]

It can be difficult to diagnose when one phase of a three phase system goes out. I could tell you stories from when I worked in a nuc plant, but they are pretty boring.

[Tony D]

This is why industrial customers usually knuckle under to Hartford Steam Boiler Company (insuracne company) when they demand annual Infra-Red testing of all MCC panels and Switchgear.

 

Had anyone shot a simple infra-red photo of the switchgear, loose and corroded connections show up with PLENTY of warning.

 

I deal with this on Centrifugal Compressors all the time, power sag on one leg causing a compressor overamp trip because of low power input. Shut down a process that costs a customer $1,000,000 an hour because they drop air pressure, and all of a sudden the I-R Photography becomes cheap insurance indeed.

 

There are plenty of Companies locally that can provide this service. BEST (Blivens Energy Scanning Techniques) is one out of Long Beach. I have dealt with them since 1989, and the owner is a really good guy. If you are flexible on when they come by, they can shoot or scan your panels pretty cheap. Especially if you are in the area of a bigger company getting something done.

 

Even shooting the connections with a good I-R Temp gun can show the loose connections. But when you see the I-R Photo, it becomes obvious where your problems are.

[johnc]

Unfortunately, as a leasee in light industrial complex, even if I found a problem at the main panel, the landlord won't do squat until something actually happens. Since I've been here (4 years) this problem has happened to 3 other tennants. All of our suggestions about preventative maintenance fall on deaf ears when the park is bought and sold between three of the same Birtcher "investment partnerships" (doctors and lawyers with money and no clue) every two years.