Bkessler

I have a brand new 15 hp motor wired (marathon t215 frame Ithink) wired at actual voltage is 490. It ran for three days fine, although in hindsight they thought it was warmer than it should be, then blew a fuse one day, ran fine then just stopped working now there is a direct short to ground. Any Ideas why this would happen. Motor says it rated 230/460 it is definetly tapped correctly but the actual building voltate was 492. Could this cause the motor to go.

__________________
When ls lunch

TheRick

The increased voltage would only reduce the current draw by the motor, so likely not the source of the heat, or the shorting to ground.

I would double check your connections, there is generally a diagram on the nameplate for both the HI and LOW voltage connections. How did you terminate the T-leads in the peckerhead? Was the current draw checked when the motor was placed in service to ensure it was below the F.L.A. rating of the motor?

__________________
Rick Boudreau
TASK FORCE SAFE INSPECTION TEAM LEADER
Tal Afar, Iraq
"fool-proof systems do not take into account the ingenuity of fools"

nap

the voltage is well within tolerances. NEMA requires motors to be able to handle a +/-10% variance of of nameplate voltage so untill voltage hits 528, there should be no problems.

In my area 500 is pretty normal for the 480 nominal systems. No undue problems that I have seen.

Bkessler

When I went down there and hooked it up it was a motor on a stand with a some pump on it. We turned it on and just he let it pump oil from it's tank to a 55 gallon drum and it worked fine. He mentioned they disassemble big rigs, so I thought the thing was just to pump oil from one tank to another or something.
Today there was a trailer that goes on a semi truck backed into the shop and they had rigged the thing up to a pallet jack and what looked like the control rigging of a crane and were running some giant concubine that turned about 9 yards of wet sawdust and manure mixture with a big tiller style blade turning the mixture. Today I find out the owner of this outfit is actually extremely crudely trying to make a homemade version of some farm tool. So what ever ran the original machine he had was some giant farm tractor. I think our little electric motor was just overworked. Then he asked my if I knew how many horse power a bobcat was. I said "no" Then he said "thats what size electric motor I need".

__________________
When ls lunch

micromind

Generally speaking, when a motor runs hotter than it should, it's usually because of overloading, or single-phasing, or even partially single phasing. In either case it should have tripped the overloads in the starter before it burned up.

It's entirely possible that it had an internal defect though, if one of the winding turns shorted to an adjacent turn, it would likely take a few days for the fault to spread into the rest of the stator.

What is the insulation class? If it is class F, or G, the frame will run hot enough that you can't hold your hand on it for more than a second or so.

Is the voltage to it balanced? On a 480 volt system, a 15 volt spread from the highest leg to the lowest one will start to cause trouble, 25 volts will really cause problems.

Most likely it was connected correctly, or it wouldn't have lasted for more than a few minutes. My strongest suspicion is a bad motor.

490 volts is reasonable, around here a 480 service will run anywhere from 490 to 500.

Rob

micromind

A Bobcat runs about 20-40HP. A small farm tractor is about 30HP, medium size is around 100HP, and the big 4 wheel drive articulating ones are about 300HP.

Rob

TheRick

Sounds to me like the motor was overloaded and burnt up. Was there any OL protection for the motor, and if so was it old fashioned heaters or a solid state overload relay? If heaters were they sized appropriately, and if solid state was the setting correct.

It is way too easy for an operator who doesn't understand the ramifications to crank an OL setting up because "the damn thing just keeps tripping", not understanding that the OL is protecting the motor from the very fate I believe this one has suffered.

__________________
Rick Boudreau
TASK FORCE SAFE INSPECTION TEAM LEADER
Tal Afar, Iraq
"fool-proof systems do not take into account the ingenuity of fools"

nap

from that last post of bkesslers, it sounds like they probable put a cord on it and plugged it into the wall



I love this line:

I hate to admit my shortcomings but I don't think I could handle a giant concubine.

TheRick

DITTO

__________________
Rick Boudreau
TASK FORCE SAFE INSPECTION TEAM LEADER
Tal Afar, Iraq
"fool-proof systems do not take into account the ingenuity of fools"

randomkiller

I prefer mine in the 110#-125# pound range myself, hell I wouldn't have any interest in a giant one either. But from reading that post, it sounds like she has some crazy talents.

__________________
A Veteran - whether active duty, retired, guard or reserve - is someone who, at one point in his life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including my life."

"One Nation Under God"

Mountain Electrician

I'll take 3 of the 125 pounders, please. Although (1) 375 pounder might be interesting!

randomkiller

Speaking from (Oki) experience, two of the 100's do just fine, three will wear you out in an hour. And if you have a whole weekend to kill, it brings down the mood. As for the 375#, I have only heard of rolling them in flour and looking for the wet spot and that is just how it's going to stay.

__________________
A Veteran - whether active duty, retired, guard or reserve - is someone who, at one point in his life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including my life."

"One Nation Under God"

John

And you might experience the "Grand Canyon Effect". Make sure you tie a 2 x 4 to your stern so you don't fall in. Remember safety first.

__________________
Doubt All Before Believing Anything.......

Mountain Electrician

That big 'un will keep you warm in the winter and give you some shade in the summer.

I've got a kid that works for me that says he loves BMWs....Big Maine Women. I saw his girlfriend, and he wasn't lying!

randomkiller

God bless him, they need love too and he's on a mission.
He can have the ships, I'll stay with the dingys.

__________________
A Veteran - whether active duty, retired, guard or reserve - is someone who, at one point in his life, wrote a blank check made payable to "The United States of America," for an amount of "up to and including my life."

"One Nation Under God"