Re: (ET) E15 alltrax death

[Tim Humphrey <hump evgrin com>]

> 
>>
>>
>> -----Original Message-----
>> From: elec-trak-bounces cosmos phy tufts edu
>> [mailto:elec-trak-bounces cosmos phy tufts edu] On Behalf Of David Roden
>> Sent: Tuesday, December 04, 2007 9:02 AM
>> To: elec-trak cosmos phy tufts edu
>> Subject: Re: (ET) E15 alltrax death
>>
>> On 4 Dec 2007 at 7:42, Konstanty, Walter (GE Indust, ConsInd) wrote:
>>
>>> The motor can't generate a spike as
>>> it's a resistive element.
>>
>> What kind of motor is pure resistance?  All the motors with which I'm
>> acquainted, being electromagnetic devices, have some amount of
>> inductance.
>> Some types have more than others, of course.
>>
>> That said, my gut reaction is that the PTO contactor is the likely
>> culprit,
>> mainly because I've seen HUGE spikes from contactors without suppression
>>
>> diodes.
>>
>>> if the voltage drops low enough it might "shut off" the Alltrax SCR's.
>>
>> I'm pretty sure the Alltrax is a MOSFET design.
>>
>>
>> David Roden - Akron, Ohio, USA
>>
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>>
>>
> 


I'm thinking two MOV's, one across the contacts and the other across the 
coil of the PTO contactor may be cheap insurance. Or maybe better to put 
one high power one across he Alltrax terminals, then the tractor wiring 
can help absorb some of the induced energy. 
 
 
--
Stay Charged!
Hump
I-5, Blossvale NY