Motor is pulling twice the nameplate current ?

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I have a 230V/460V induction motor. Nameplate says amperage is 17A/9A it's turning a blower. It's a 12 lead motor and instead of numbers 1 through 12 on the labels it's all U,V,W`s with each in U1,U2, U5, U6 and so on for V and W. I have the motor wired to 480V per the diagram on the terminal cover for high voltage at 460V and the motor is pulling 17A. This was determined by clamping on to one phase. This is the steady reading after the inrush of about 50A at start up. What is the problem? Why ain't it pulling the 9A as it says?
 
New to maintenance said:
I have a 230V/460V induction motor. Nameplate says amperage is 17A/9A it's turning a blower. It's a 12 lead motor and instead of numbers 1 through 12 on the labels it's all U,V,W`s with each in U1,U2, U5, U6 and so on for V and W. I have the motor wired to 480V per the diagram on the terminal cover for high voltage at 460V and the motor is pulling 17A. This was determined by clamping on to one phase. This is the steady reading after the inrush of about 50A at start up. What is the problem? Why ain't it pulling the 9A as it says?
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U,V,W is common motor lead labeling for VFD's and simply gives you a visual of your winding pairs on a motor. Any chance you can snap a picture of the wiring diagram on the motor? Also, is there a chance the motor is overloaded/undersized causing the high readings?
 
iwire said:
After checking my connections the next step for me would be figuring out if it is a mechanical issue or an electrical one.

Get that pinned down and go from there.
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Again, I agree. An uncoupled run should sort that out. It should draw around 30-40% of the FLC.
 
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I had a large 3 phase 480 volt motor on a sawdust blower at a sawmill There was to be a 100 foot (approx) run of 18 inch duct to blow the sawdust to the sawdust shed.

The motor drew way too much when we tested it before hooking it to the duct. Turns out it needed the static air pressure created by the duct to hold it back from over speeding. Testing it without the load in this case led to us thinking "bad motor".

We had the mill guys hook it to the duct and the Amp draws fell into line just fine.
 
Something that I don't think has mentioned yet.
It might be worth checking the winding resistances for continuity and balance.
 
After verifying proper connections block either inlet or outlet of the blower. This should significantly reduce motor current if it is a centrifugal type blower. If it does you either have too small of a motor for the application, or something isn't set up right with air flow. Or even possible you have a 3400 rpm motor installed on something designed to use a 1750 rpm motor.
 
kwired said:
After verifying proper connections block either inlet or outlet of the blower. This should significantly reduce motor current if it is a centrifugal type blower. If it does you either have too small of a motor for the application, or something isn't set up right with air flow. Or even possible you have a 3400 rpm motor installed on something designed to use a 1750 rpm motor.
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Excellent points, especially the last one. I've seen that happen more than once. Similar to that, the motor was picked out as a belted operation based on a specific sheave ratio and was either connected to the blower directly or the sheave ratio is wrong, even backward!

And along that same vein, U,V,W connections implies this is an IEC motor, designed for 50Hz. If you connect it to 60Hz, the motor runs at 120% its design speed. In a centrifugal fan, power changes at the cube of the speed change, so the HP required at 60Hz will be higher than the design based on 50Hz by a factor of 1.23, which is 173%. In other words if the blower was expecting to be used in a 50Hz environment, connecting it here means the motor is too small, or the sheave ratio (if any) needs to be changed accordingly.
 
Jraef said:
the motor was picked out as a belted operation based on a specific sheave ratio and was either connected to the blower directly or the sheave ratio is wrong, even backward!
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That makes me think: Question for the OP - the motor is running in the right direction, correct?
 
tkb said:
It's always an electrical problem, until we prove otherwise.
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Even when it's not...

My favorite was when I installed a VFD for a customer at HIS request for a 100HP pump motor used to pump out a collection tank. I didn't sell him the pump, I just sold him the drive and controls and installation / programming of it all. The tank had to maintain a certain level to avoid sucking air into the line, so I used an ultrasonic level transducer feeding a PID loop in the drive. Worked perfectly in my shop, installed it, tested it, worked perfect in the field under the conditions they gave me to test it. A week later I get a call because the tank is over flowing; the VFD is not keeping up. I go out and the drive is at full speed, but the inflow is greater than the pump can handle. Somehow this is MY fault? I look around more and see an old pump, find out that's what was being replaced. Turned out the old pump was 400HP, the new one was 100HP. Hmmm... why would someone ASSume that a 400HP pump could be replaced with a 100HP pump and do the same job? So this was NOT an "electrical" problem, but I was the only one there, so I was getting the blame. Pump supplier is who told him it would work, not me, but he refused to back down, insisting this was an electrical issue. I had to reconnect the 400HP pump to an old Autotransformer starter they had there to prove it to them... Didn't get paid for that part of it though. I told them the real solution was to have installed a VFD on the 400HP pump they already had and slow it down when not at full capacity, they didn't need a new pump. But they hadn't asked me that. They eventually did abandon the new pump and go with the 400HP drive, but I insisted on getting paid for my "test" so they just went with someone else for the new VFD.

A year later I had to go back out to make that one work right too, so eventually, they ended up paying me what I wanted...:p
 
New install or just a motor replacement?
what is the blowers function? Aeration of a tank, moving material, etc
motor speed
relative pulley sizes

sounds like 7.5 HP
sounds like miswired
can't imagine the blower is so mis-sized
either working pressure is too high or over-driven
 
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