Increase Motor Capacity
Increase Motor Capacity
(OP)
Hello everyone! I'm looking into increasing a pulverizer motor capacity from 150HP to 250HP. Does anyone know of any good material on that? What methods are used to increase capacity, and what are the considerations? Thanks!





RE: Increase Motor Capacity
If you are increasing the power rating at the same operational speed then you will need to be aware of the complete transfer of power from the electrical supply through to the mechanical transmission. A few basic questions:
1) You seem to have determined that your power requirement needs to increase by 100hp. I would have to assume that you have done calculations to determine this fact.
2)To start, run and operate a motor with an increased power rating will obviously increase the current demand and therefore all the switchgear connected to the motor. It needs to have the increased capacity to do so. If you are starting the motor DOL then this is going to be included in the switchgear sizing. If the motor is using an electronic softstart or VFD, then again, this is required to match the motor.
3) The cabling may need to be increased.
4) The motor will be bigger so mechanically, you will need more space, different mountings for the motor and, however the motor is coupled to the pulverizer, will need to be modified.
5) More power at the same speed means more torque. The motor shaft will be bigger to accommodate the increased torque and therefore the coupling (if used) will be bigger. If there is a gearbox between motor and pulverizer, then this needs to be determined if it will cope with the increased torque.
6) looking at the actual pulverizer. Is this capable of the increased power/torque? There is no point in doing all this if the nett result is your actual pulverizing machine is what gets pulverized itself.
Just a few tips.
4)
RE: Increase Motor Capacity
RE: Increase Motor Capacity
Add more coils?
You mean, install a new motor - and switching gear?
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: Increase Motor Capacity
Muthu
www.edison.co.in
RE: Increase Motor Capacity
RE: Increase Motor Capacity
Rafiq Bulsara
http://www.srengineersct.com
RE: Increase Motor Capacity
Who is giving you these ideas ?
You can't get 66% more power from the same motor unless there is a corresponding increase in motor speed. And there are mechanical and electrical design issues with increasing the motor speed. You can't do it just like that.
Buy a new motor.
Muthu
www.edison.co.in
RE: Increase Motor Capacity
Install a very chilled forced air cooling system...
Increase the voltage and frequency by 67% and then installing a reduction drive to bring the speed back down...
Honestly, good luck.
RE: Increase Motor Capacity
Uprating a motor is sometimes done but generally reserved for larger motors and smaller incremental changes. Often for medium voltage form wound motors there is an improvement by improved insulation materials operating at higher volts per mil which allows adding more copper. I'm guessing your motor is a low voltage random wound and there is not much savings in insulation size to be realized. There are a few other tricks that rewinders like edison and others here use: higher slot fill, higher flux density, higher temperature rating on insulating materials...but probably will need a whole lot of tricks and some magic to get that much increase.
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RE: Increase Motor Capacity
RE: Increase Motor Capacity
But, the limit has about been reached. Now, the solution to more power is to use over voltage and over frequency and gear or belt back down to the speed that you need.
This works fairly well with 230/460V motors rated for inverter duty. All the windings are suitable for the application of 460 Volts so the motors are connected for 230 Volts and supplied with 460 Volts at 120 Hz. This technique is used by some skid mounted equipment manufacturers for new equipment but it isn't a good idea for older non inverter duty motors. The PWM wave form tends to destroy older motors.
Flux density is not an immediate problem. The primary issue is dissipating the I2R losses.That is why we want a greater cross section of copper or the ability to run hotter. Breakdown torque may not increase so starting heavy loads may present issues.
Bill
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"Why not the best?"
Jimmy Carter
RE: Increase Motor Capacity
Don't forget that when you do this, you have added mechanical losses to the equation, probably at least 20% (80% eff through the gearbox) so that 67% increase probably goes to a 100% increase before the gear-down (1.67 /.8).
So to take that out to a conclusion with the goods at-hand, to get 250HP net at the shaft from an existing 150HP 460V 60Hz motor, you will need to add a VFD running at 120Hz and increase the input voltage to 920V. Your throughput efficiency will drop precipitously.
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RE: Increase Motor Capacity
How about reconnecting for 230 and using 480 Volts? Not that the old motor will last long on PWM service.
Bill
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"Why not the best?"
Jimmy Carter
RE: Increase Motor Capacity
Go here and search for 6345S in the top search box.
http://www.surplusrecord.com/adv_search.html
There are a few induction and wound rotor motors listed there with the appropriate size.
Is this a wound rotor motor? If so, then the rotor and stator may both need re-worked to upgrade the HP. To me, that sounds like a motor that was built to match a specific specification, in other words a custom ordered motor.
You really need an expert to evaluate your motor and tell you what could be done. We can't teach you how to be an expert at this over the internet.
RE: Increase Motor Capacity
Got a 100 HP 600 rpm motor lying around? Or a second 150 HP motor? Depending what the back of the existing motor looks like, a few couplings and some I-beams and channel might allow you to do something like this.
http://www
RE: Increase Motor Capacity
It sounds like Lionel found some very promising leads. For example:
htt
MOTORS, A.C., SQUIRREL CAGE, 60 CYCLE (Also See Explosion Proof) 300 HP 590 RPM General Electric, Fr.6345S, DP SB, 460 V. (5)
Same frame number means proper mechanical interchangeability. Same horsepower, speed, voltage.
There might be a few smaller details to check:
* Term box on correct side (if not can you move it.... or can you adapt your wiring).
* Is the enclosure suitable for your environment.
* Proper accessories (space heaters with correct voltage). Or can you backfit, or adapt to what they've got.
* Since it's a surplus....Is the motor in working order? Does it run? With acceptable vibraiton? Has it been meggered / bridged? Or is there a warranty?
* Is it the right color? (Just kidding).
Also as mentioned you'll have to check your cables and breakers for capacitity as well as setpoints to permit starting and running. That will be the case for any 250hp 460vac solution you pick.
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RE: Increase Motor Capacity
RE: Increase Motor Capacity
RE: Increase Motor Capacity