Re: Identifying Current and Voltage on vaguely marked MOT. (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 27 Aug 2007 18:43:07 -0700
From: Barton B. Anderson <bartb@xxxxxxxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Identifying Current and Voltage on vaguely marked MOT. (fwd)

Oops! I made a critical mistake. For Primary reactance, this is an OPEN 
CIRCUIT test. Don't short the secondary, you'll blow your meters current 
fuse (short circuit test is different).

Primary reactance = Pri Voltage / Pri Current (both measured with the 
secondary "NOT" shorted)

Sorry about that. I got too quick with the old typing fingers.

Take care,
Bart

Barton B. Anderson wrote:

> You need to measure to find out actual specs. Most MOTs will be less 
> than 2600 Vac and many meters will read about 700 Vac. That's a little 
> less than a factor of 4. But, protect your meter by being smarter than 
> the voltage. If you have the capability to vary the AC voltage from 0 
> to full voltage (like a variac), start at 0V and slowly increase the 
> voltage until you are just below the meters specifications. Log down 
> the voltage on both the primary and secondary sides of the transformer.
>
> Here are a few basic calcs from a few simple measurements:
>
> Turns ratio = Vsec/Vpri (as stated above)
> Sec Volts = Turns ratio x Vpri (at 120 Vac)
> Inductance ratio = Turns ratio x Turns ratio
> Primary reactance = Pri Voltage / Pri Current (both measured with the 
> secondary shorted)
> Primary inductance = Pri reactance / (2 x PI x Hz)
> Secondary inductance = Pri Inductance x Inductance ratio
>
> Take care,
> Bart
>
> PS: As always, becareful with these type of measurments (lots of AC 
> floating around and easy to get zapped).
>
>
> Tesla list wrote:
>
>> ---------- Forwarded message ----------
>> Date: Mon, 27 Aug 2007 00:21:46 -0500
>> From: Glen McGowan <glen.mcgowan@xxxxxxxxx>
>> To: Tesla list <tesla@xxxxxxxxxx>
>> Subject: Identifying Current and Voltage on vaguely marked MOT.
>>
>> Just curious if there's some super secret math out there that can 
>> help me
>> identify the rated voltage and current of a MOT.  I only have one 
>> variable
>> for the equations.... the MOT is labeled with 700W output. That's 
>> it......
>>
>>
>>
>>
>>
>>  
>>
>