Interesting motor comparisons

Awl--

Got a 10 hp Baldor up and running--someone had misread the numbering on the wires, and thus miswired the motor--blowing fuses like crazy.

Inyway, I amprobed it, and a 5 hp Magnatek. Would you believe the 5 hp Magnatek, no load, draws substantially more current than the Baldor??? About 20-30% more. wow.... I don't know if that's because the Mag is really piggy, the Baldor super-efficient, or both.

The Mag, however, seems to have better bearings, as it spins quite a bit longer w/o power.

Also noticed wide variations in the current draw of each leg (both motors). For example, I read 3A on one leg, 9A on the other, 12 A on the third, operating off an rpc. Is that normal? In NYC-supplied 3 ph, I seem to remember identical current draws on each leg of a 3 ph motor (208 V).

-- Mr. P.V.'d formerly Droll Troll

Reply to
Proctologically Violated©®
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Procto sez:

The current draws of commercial 3-phase and RPC's are not ever going to be the same. This is because a RPC is, in reality, is an electrical network comprised of both idler and load motors. I suggest you do a bit of study on RPC's. There are good links on Google and Metal Web News.

Bob Swinney

Reply to
Robert Swinney

An Amprobe is meaningless, without knowing the power factor. The magnetek could actually be drawing less POWER, even though the line current is higher.

It means your RPC is not balanced.

Utility 3-phase is usually very well balanced, so no surprise.

Jon

Reply to
Jon Elson

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