Mains isolation transformer (Va.)

[Ville Voipio]

Due to some rather annoying industrial ground loop problems
(piping potential is far away from the network PE) we would
need a mains isolation transformer:

- 115 Vac : 115 Vac / 60 Hz
- 300 VA
- UL (or other appropriate) certification

A very simple device, no doubt. Unfortunately, our service guy
is in Richmond, Virginia. I would know where to get
such a transformer for 230 V/50 Hz on this side of the Atlantic,
but that does not help much...

So, if you have any idea where to find the transformer in
Virginia, that would help a lot!

TIA,

- Ville

 

[Walter Harley]

Due to some rather annoying industrial ground loop problems
(piping potential is far away from the network PE) we would
need a mains isolation transformer:

- 115 Vac : 115 Vac / 60 Hz
- 300 VA
- UL (or other appropriate) certification

They're easy to mail-order, from places like Digikey, Jameco, Mouser,
Newark, Grainger... 300VA is an easy size to find.

However, if you are using this in an industrial setting you should be
working with a licensed electrician to be sure your work meets the
electrical code. You can't just lift grounds!

In particular, here's something I think you can't safely or legally do: plug
an isolation transformer into circuit "A"; plug equipment "X" into the
isolation transformer; and ground "X" using a ground wire that runs to
circuit "B", separately derived from "A". Especially if the ground wire
isn't a rated conductor of adequate gauge. The reason is that if the hot
output from the transformer shorted to ground, no circuit breakers would
trip.

If this is just a temporary thing to get some test gear working, forget I
said anything

 

[Ville Voipio]

They're easy to mail-order, from places like Digikey, Jameco, Mouser,
Newark, Grainger... 300VA is an easy size to find.

Thank you! I tried Digikey (not in stock) and Newark (something
in stock), but Jameco, Mouser, and Granger were less familiar.
It seems that Mouser have some good parts, so that may solve the
problem.

However, if you are using this in an industrial setting you should be
working with a licensed electrician to be sure your work meets the
electrical code. You can't just lift grounds!

Yup. Would not cross my mind to do anything in somebody else's
plant without having their electrician taking the responsibility...

If this is just a temporary thing to get some test gear working, forget I
said anything

Extremely temporary.

Thanks once again!

- Ville

 

[Walter Harley]

Thank you! I tried Digikey (not in stock) and Newark (something
in stock), but Jameco, Mouser, and Granger were less familiar.
It seems that Mouser have some good parts, so that may solve the
problem.

Another electronics distributor I didn't mention is Allied, at
http://www.alliedelec.com, who are showing stock on a Hammond 300VA
isolation transformer for about $73.

Grainger (note the 'i') is an industrial-supply chain. They do mail order
but they also have retail outlets; so if you're in a hurry you may be able
to find one close to you. They're a great source for replacement motors,
pulleys, belts, AC capacitors, things like that, as well as selling
everything else industrial from hand cleaner to drill presses. However,
they tend to be expensive.

(I have no association with any of the sources mentioned, by the way.)

 

[Watson A.Name - \Watt Sun, the Dark Remover\]

Due to some rather annoying industrial ground loop problems
(piping potential is far away from the network PE) we would
need a mains isolation transformer:

- 115 Vac : 115 Vac / 60 Hz
- 300 VA
- UL (or other appropriate) certification

A very simple device, no doubt. Unfortunately, our service guy
is in Richmond, Virginia. I would know where to get
such a transformer for 230 V/50 Hz on this side of the Atlantic,
but that does not help much...

So, if you have any idea where to find the transformer in
Virginia, that would help a lot!

TIA,

Try Grainger. www.grainger.com and search for keywords isolation
transformer. I found several.