Need a 240V to 120V 100W transformer?

Autotransformer

SAT200 - BLOCK - Auto Transformer, Class I, 115 VAC, 200 VA, 1.74 A | Farnell element14

That's brilliant thank you so much!

Could I enquire if that transformer is also what is termed an 'isolation' transformer? I've been told that all transformers are isolation transformers, yet I see products such as this one which specifically says isolation in their names The monitor I wish to power has a little label on its power lead which says'Warning isolation transformer must be used In this context does isolation mean something different or am I ok to go ahead and order the Block  SAT200SAT200 you linked to

Many thanks for your help.

No, it is _not_ an isolation transformer.

Autotransformers only have a single winding which is tapped to give the output.

Isolation transformers have two or more windings which electrically separates the output circuit from the input circuit.

ST 130/23/11 - BLOCK - TRANSFORMER, ISO, 110VAC, 130VA | Farnell element14

Thanks again for such a prompt reply. Goodness it's much more expensive than I was hoping for. Could I enquire if that's the cheapest isolation transformer with my required specifications? I'm sure it likely is, but I thought I should confirm in case you offer any cheaper options? For instance, is the cheaper Schnieder Electric one I linked to not the appropriate specification as well?

Shop around. I'm just quoting from the Farnell catalogue as this is an Element14 forum after all.

Got space for a site isolation transformer ?

PRO ELEC - P075/1 - Isolation Transformer, 750 W, 1 x 230V, 110V, UK | CPC UK

The Schnieder Electric one you linked to was only rated at 25VA. The 100VA version is more expensive.

ABL6TS10U - SCHNEIDER ELECTRIC - Isolation Transformer, Phaseo Optimum, 100 VA, 1 x 230V, 1 x 400V, 230V, 2.5 A | Farnel…

The other question would be why it needs to be isolated. Is it a metal chassis which isn't earthed ? Also the question is who stuck the label on the power cord as it may not have been the manufacturer. Have you got access to a user manual for it ?

Thank you for putting me straight on that. I feared I might be not understanding the terminology correctly. Unfortunately it does seem to require isolation. It is in an open chassis and is a Wells Gardner K7000.

I wish that site isolation transformer would fit but it looks too big unfortunately. I'm slightly reticent to buy from other places since element14 does come recommended as having quality components. Would you be able to tell me if the price for the Block ST130 is indicative of the price I'd expect to pay for such a transformer, regardless of the make or where it was purchased?

Hi Jim,

That is a reasonable price, it is a hefty piece of metal. That is a typical size too, by nature of what it does and power rating.

Like you, I'd be concerned about buying one from elsewhere like ebay etc), because it might be unsafe.

Cheaper option would perhaps be this

TIM100 - BLOCK - Isolation Transformer, Class II, 100 VA, 1 x 230V, 2 x 115V, 430 mA | Farnell element14

and it appears to be in stock with no extra shipping charge.

The dual outputs would have to be connected in parallel though.

Not W, but VA for some reason.  I think because the transformer is a passive device.