96V output transformers.

[Cicada]

Hi

For cheap I can buy a very beefy (second hand) 220V to 96V transformer. I plan to use one as a safety isolation transformer together with a 2.5KVA variac that I have.

Where (in what equipment) does one usually see these 96V output transformers?
Inverters?
Motordrives?

and why 96V?

Thanks

[Ian.M]

That depends on the secondary configuration.  Does it have a center tap?  If so, possibly an audio power amp, otherwise probably old big DC motor drives.

IMHO its not a good choice for an isolation transformer unless you can get two of them to use back to back, or if you use a single one backwards, if you add a mechanical stop to your Variac knob at 100V.  Make sure your Variac output is fused (or has a circuit breaker) at the lower of its rated wiper current or the transformers rated secondary current.

Personally, I'd choose to set it up with a beefy bridge rectifier and a decent sized bank of 160V rated electrolytic reservoir caps, for use as an isolated variable (but unreguated) DC supply with the Variac, for experimenting with largish motors, etc.  N.B. the max. permissable continuous DC current is at most 62% of the secondary's RMS current rating.

If its got a center tap, use 100V caps between the center tap and the bridge + and - terminals, for either symmetrical positive and negative rails suitable for audio power amps, or if you draw between bridge + and CT with no load on bridge -, DC at half the voltage and up to 100% of the secondary RMS current rating.

[Pawelr98]

If you already have a variac then just get a 100-120V/220-240V transformer and adjust the voltage as required.

Also you don't even have to use one transformer.
Get two transformers with 2x24V secondaries (those are plentiful and cheap) and connect them in phase.
You will get those 96Vac this way.

[jbb]

It’s a guess, but the 96V may be targeting a 120V DC output. This is used in some power substation control rooms (plus a big stack of lead acid backup batteries). Maybe also some industrial systems?

96V AC is a bit odd, otherwise. Above Safety Extra Low Voltage, but still less than the typical 120V / 240V line voltage...