Re: (ET) Power of Elec-trak motors?

["David Roden" <etpost drmm net>]

On 4 Jun 2010 at 9:28, Christopher Zach wrote:

> Hm. Well how can we check this? One thing I have is the Link-20 which 
> can tell me current being pulled from the batteries under load.

Not that way.  As I suggested before, measuring the power into the motor 
tells you nothing about the manufacturer's rating of that motor.  You 
could 
even measure the output on a dynamometer, and you STILL wouldn't know 
anything more than you do now.  

The fact is that every electric motor can produce several times its rated 
nameplate power for some period of time, though usually not continuously.  
So you can ALWAYS measure more hp output (and kw input) than the nameplate 
claims.  

GE would have no incentive to lie about their motors, other than in their 
advertising.  <g> If the published engineering data say the drive motor is 
rated at 1hp, most likely it is, as puzzling as that may be to folks used 
to 
the way ICEs are rated for absolute peak horsepower.

Look at the EV drag racers.  They use what are essentially forklift 
motors, 
nameplate rated at perhaps 30-40hp.  They may make some modifications to 
them, such as adjusting brush timing, wrapping the commutators with Kevlar 
filaments, and/or applying extra high temperature varnish to the windings, 
though many of the less serious weekend racers don't bother.

They run these motors as high as 300 volts, and at a thousand or two amps. 
Taking efficiency into account, this is an output of around 300-600hp!  If 
they don't fireball the commutators, the motors usually last long enough 
to 
get down a 1/4 mile dragstrip at least a few dozen times, sometimes more 
than that.

Given that, it's not surprising that GE ads claimed (in a cringe-inducing 
confusion of units) that with a 1hp motor "peak torque exceeds 14 
horsepower."


David Roden - Akron, Ohio, USA

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