220v to 110v autotransformers or isolated transformers?

[neazoi]

Hello,
I live in a country where the mains voltage is 220v but some of my lab equipment (scopes, soldering station) operate on 110v (bought from US).
Is it safe to use these commercial autotransformers to reduce the voltage or should I better order custom standard isolated transformers to do the job?
These instruments DO work with the autotransformer, I am just asking because these instruments are delicate, so I would like to know if some problems could be caused by the use of the autotransformer (spikes, non-isolation related problems, etc)

 

[THINKER_KAM_MAN]

Hello,
I live in a country where the mains voltage is 220v but some of my lab equipment (scopes, soldering station) operate on 110v (bought from US).
Is it safe to use these commercial autotransformers to reduce the voltage or should I better order custom standard isolated transformers to do the job?
These instruments DO work with the autotransformer, I am just asking because these instruments are delicate, so I would like to know if some problems could be caused by the use of the autotransformer (spikes, non-isolation related problems, etc)

there will be no problem, you can use an auto transformer.
but remember, all mains equipment should be earthed properly for safety. also you should use a RCD breaker.

 

[dick_freebird]

I would suggest to use the isolated transformer because I
have had trouble with my benches being "mildly hot" even
when grounded to the wallplug. The building wiring is not
that great, the phase loading is a bit unbalanced and I see
a few volts of ground amplitude relative to other non current
carrying ground points (plumbing). With an isolating transformer
you can make ground and neutral referred to a quiet solid
ground of your choosing. An autotransformer would leave
you with whatever the AC power has going on. Having your
'scope "ground" riding on garbage, tends to add "stuff" to your
signals.

I picked up three 1kVA 220:110 isolation transformers last
month so I can redo the entire set of benches all nice-nice,
star earth ground.

 

[neazoi]

I would suggest to use the isolated transformer because I
have had trouble with my benches being "mildly hot" even
when grounded to the wallplug. The building wiring is not
that great, the phase loading is a bit unbalanced and I see
a few volts of ground amplitude relative to other non current
carrying ground points (plumbing). With an isolating transformer
you can make ground and neutral referred to a quiet solid
ground of your choosing. An autotransformer would leave
you with whatever the AC power has going on. Having your
'scope "ground" riding on garbage, tends to add "stuff" to your
signals.

I picked up three 1kVA 220:110 isolation transformers last
month so I can redo the entire set of benches all nice-nice,
star earth ground.

The autotransformers I have in hand are like this one **broken link removed** but there is no ground on the 220v side. There is a ground cable on the 110v side though but I believe it is just connected to the case.
Wou say there might be a noise or induced voltage on the scope equipment, but do you think it will matter for the soldering station? It is a weller wrs1000

 

[BradtheRad]

There is a risk in case the transformer was made for 60 Hz (assuming your mains is 50 Hz). You'll need to watch for overheating due to saturation, and drawing too power.

**broken link removed**

 

[THINKER_KAM_MAN]

The autotransformers I have in hand are like this one **broken link removed** but there is no ground on the 220v side. There is a ground cable on the 110v side though but I believe it is just connected to the case.
Wou say there might be a noise or induced voltage on the scope equipment, but do you think it will matter for the soldering station? It is a weller wrs1000

because test equipment have isolating transformers built into them
you should not have had problems with the auto transformer
it may have been your ground.
however for safety the isolating transformer is better.