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Air Line Arm Owners- Compressor Electrical Noise

As mentioned in another thread, I finally got the Air Line arm installed on the XL table, on the finite stand, etc. I installed the arm compressor in a separate 'room' (in reality a large walk in closet off the listening room) and powered the compressor from a 'regular' circuit outlet- the system is otherwise hooked up to its own dedicated lines, per standards discussed many times here.
I have been experiencing a periodic electrical 'zap' (sounds like a big ol' scratch on the record) through the system when the gain is up. Since the room lights dimmed when the compressor kicked on, I figured- why fool with the standard circuit to feed the compressor? I had the electrician come back and set up a separate line just for the compressor- having nothing to do with the system wiring or subpanel. (He had already pulled extra wire through the conduit up into the room, so it was no big deal to do this- he installed a high quality receptacle to this extra line, and terminated it at a different subpanel than that which runs the audio system).

Anyway, still that nasty zap. Never out of options, I decided to plug the compressor into a 240v-120v stepdown transformer I use to power the HT system in the same room. (The HT system is completely separate from the analog hi-fi system we are concerned with here).
So far, so good- the compressor kicks on, but no zap.

Still monitoring the situation- wondering whether other Air Line owners have experienced similar problems (which may be reassuring if this is the cause and I licked it) or I am still chasing electrical gremlins. TIA.
128x128whart
qzm
1 posts
 
The electrical noise generated by the compressor when switching on, occures every few minutes and is similar to that which occures when a domestic refrigerator switches on. It is transfered via the mains not the air and can be solved by having a separate mains feed. If this is impossible or ineffective however, we have a "zero switch relay kit" which can be installed in the compressor and which normally solves the problem.

Franc Kuzma,www.kuzma.si
whart's avatar
whart OP
3,036 posts
 

Thanks for the responses, gents. (Franc- you have been constantly responsive to me in the past, for which I thank you).
Interestingly, I had the compressor wired to a separate receptacle, connected via very high grade wire to a separate breaker in a separate subpanel from the subpanel which services the audio system power. That, alone, did not prevent the 'zap.'
I then plugged the compressor into an outlet on my 240v stepdown transformer, which seemed to reduce, but not entirely eliminate, the zap.
I then plugged my electronics- all of them- into an Shunyate Hydra, which, combined with the stepdown transformer hook up for the compressor, seemed to do the trick. But, I will contact Scot Markwell for this zero switch relay kit, since it will enable me to have a little more flexibility in how my components are hooked up. Regards,
jea48
4,423 posts
 
Whart posts

I had the electrician come back and set up a separate line just for the compressor- having nothing to do with the system wiring or subpanel. (He had already pulled extra wire through the conduit up into the room, so it was no big deal to do this- he installed a high quality receptacle to this extra line, and terminated it at a different subpanel than that which runs the audio system).

(He had already pulled extra wire through the conduit up into the room, so it was no big deal to do this- he installed a high quality receptacle to this extra line,
>>

I must have missed your statement about pulling extra wires in the same conduit as the feeder, if I understand your statements correctly.

In your first posting of the thread you did not mention a correlation between the "zap" and the compressor cycling off and on. I would agree the contacts that control the compressor motor could indeed cause the pop noise heard through your audio system.

I believe one issue here is the fact the circuit that feeds the compressor motor, via relay contacts, is pulled in the same conduit as the audio sub panel feeder. Current carrying conductors installed in the same raceway, conduct, can interact with one another. A current carrying wire will have a magnetic field around it. Induced voltages, though small, will will cut across to other conductors within the same conduit. Think of it working kind of like a transformer. When the control circuit for the compressor commands the relay contact to close or open a transient voltage spike is sent out on the circuit wires feeding the compressor. Jmo the compressor motor feed should be installed in its own metallic conduit back to the main service electrical panel.
Jim
whart's avatar
whart OP
3,036 posts
 
Gotcha. Makes sense. It zapped when fed by the regular old house circuit, which wasn't part of that conduit, but right now, the thing is quiet as a mouse when plugged into the 240v step down and having the system plugged into the Hydra.
The zero switch relay kit that is coming my way,, courtesy of the dealership, will hopefully eliminate the problem since I don't like running the extension cord to feed the compressor from the stepdown. (It is one of those big ugly yellow waterproof outdoor suckers- yyuuuck!)
So, Jea48, when are you going to send me a bill- or at least take a ride over and have a listen?
jea48
4,423 posts
 
So, Jea48, when are you going to send me a bill- or at least take a ride over and have a listen?
>>>>>>>
I never charge a friend. Just glad to help a fellow Audio buff.
Jim
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