[Amps] MOVs

[Vic Rosenthal K2VCO]

I put a 320V MOV across the primary of my plate transformer (no 
connection to ground) to soak up differential mode spikes, on the 
grounds that this might help protect the diodes. I have no idea if it's 
necessary or helpful, but I can't see how it could hurt. Motors like air 
conditioner compressors can produce such spikes, and I have seen cases 
in which computers rebooted themselves every time a compressor went off.

On 1/22/2014 10:45 PM, Jim Brown wrote:
> Because MOV's conduct surge currents onto ground, and the IR (and IZ)
> drop raises the potential of the chassis. When the "protected" equipment
> has a low voltage connection to other equipment powered and/or grounded
> at another point, the difference between one chassis and the other often
> fries the interface circuitry.
>
> I've seen many well-documented examples of this with audio systems, and
> with computers connected by wired Ethernet, no radios anywhere around.
> The sharp guys in pro audio stopped using MOVs at least 20 years ago.
>
> 73, Jim K9YC
>
> On 1/22/2014 10:11 PM, Jim W7RY wrote:
>> Why?
>>
>> On 1/22/2014 9:59 PM, Jim Brown wrote:
>>> On 1/22/2014 8:40 PM, Gary "Joe" Mayfield wrote:
>>>> What are folks thoughts
>>>> about MOVs on the primary side of the transformer?
>>>
>>> Bad idea. ANY MOV on branch circuits is a bad idea.

-- 
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco/