Isolation transformer

[Dr Bunsen Honeydew]

I have just bought a 4kva 1 to 1 isolation transformer that has been stripped out of a closed recording studio. New one of this quality would be approaching £1000 I paid less than £150 it weight 38 kg

So what am I going to do with it ?

[terrybooth]

Get someone to get it out of your car.

[TheMadMick]

You could make me a BB BMU??

[Dr Bunsen Honeydew]

Its an isolation transformer not a balanced transformer.

[TheMadMick]

Seemed like as good idea at the time...

[BilliumB]

Use it in circuit before the BMU?

[Fretless]

Could you use it on your house mains by the fuse box ?

[zebbo]

Be a good door stop.

[TheMadMick]

Heck of an expensive door stop when you can buy reasonably good ones at Screwfix for a few quid! But it would certainly be a talking point.

[Dr Bunsen Honeydew]

Isolation means that no direct electrical connection exists between source and load. But that's true for any transformer (other than an autotransformer). What makes the drive isolation transformer different is the placement of grounded electrostatic (Faraday) shielding between and around primary and secondary windings. That provides up to a million-fold decrease in the capacitive coupling involved in transferring common-mode voltage disturbance. Without such shielding, that capacitance allows passage through the transformer of high-frequency "noise" and transient voltage spikes.
Common-mode transients are those appearing between ground and neutral of the a-c system. (Although those two parts of the circuit are normally bonded together at one point, they cannot be presumed to be at the same potential throughout an entire power system.) Such disturbances arise from switchmode power supplies, drive operation, arc welders, lightning, or even from normal operation of such equipment as stepper motors. Some isolation transformers can also block "normal-mode" transients, appearing between line and neutral