Very Large Electric Motors

Hi All, day 2 with my PM. Very glad to find this site. I work in a refinery and besides the many hazards for anyone working there, I have concerns about being around some of the large electric motors used to drive some of our pumps. Some are as large as a small car and are upwards of 1200 - 5000hp. I also have concerns about entering what is called an MCC room. Mechanical Control Center. This is where all of the electrical breakers for plant equipment are. All different voltages up to 2300kva. It's early here and I'm waiting to contact St Jude Med later today but, does anyone have any experience with this sort of thing? I read on the fabulous internet that I can get as close as, No Problem to 25 feet.


Electric motors

by IanMcC - 2009-08-20 10:08:07

G'Day Kiro, I can't comment on what you should or should not do but I can tell you what I do.
I work on ships that have large pumps and generators and alternators.
I have to pass close by these on occasion as close as 1 to 2 meters away, I dont linger and walk briskly past, If I can I will try to avoid going anywhere near them when they are running.
I am not too worried about the pumps (although I try to keep my distance) its the big shaft generators that I don't like.
I am not bothered in the engine control room with all the breakers,and never give it a thought.
I have never had any problems but always try to be carefull and aware. I do forget I have a pacer sometimes.
I think you will get a feel for when to be cautious as I do,
All the best, Ian.

Electrical Equipment

by ElectricFrank - 2009-08-20 11:08:05

A lot depends on the age of the equipment. Part of the increased efficiency of the motors built in the last few years comes about by not losing energy to external magnetic fields.
The same with control panels. A lot of the new equipment also uses microcomputer control systems which have about the same sensitivity to interference as our pacers. So things have been tightened up a lot.

I'm 79yrs and in my much younger days was around larger motors that were built in the 1930's. Some of those would radiate enough 60Hz magnetic energy to cause a key or bolt in my pocket to vibrate.

There are instruments that measure magnetic field levels. With all the power equipment around your facility likely has one. Keep i mind the situation can change radically with different combinations of motors ON or OFF.

So far I haven't found anything that bothers my pacer. I have gone on tours of a couple of hydroelectric plants and stood close to transformer farms and generators.

At the voltages you mention I wouldn't want to get get much closer than 25' anyway.

One thing to watch for is to avoid situations where getting light headed could risk injury.

Interesting stuff. I have always enjoyed large rotating equipment. My grandfather was a licensed steam engineer and used to take me to work with him as a 10yr old. In those days most large motors were started with a manual controller, which took some skill. He taught me how to start a 100HP blower, which was quite an experience for a young kid. Onmy first attempt I came up to fast and threw the flat belt drive.


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