1kva Toroidal transformer build

[Tutu]

Hi I recently finished a 1kva toroidal transformer build I'd thought I'd share with you.

The transformer is a 1kva dual 115v input, dual 45v output.

I'm in the UK so I wired the grey/violet together and the brown and blue to a barrier terminal. I wired the orange and black together and the yellow and red together then these went to a bridge rectifier and through 3 capacitors and then to the AM882's. So the input is wired in series for 230v input (Mine is actually 250v!) and the output is wired in parallel so I have 45v (Actually 52v) AC output.

I've added a current limiter thermistor on one of the mains input so it doesn't trip the MCB out (6amp type B)


DC voltage out

I blew one transformer up during the build (plugged the pos and neg in wrong way round on the rectifier) and the first one I bought to replace it outputted too high voltage (50v output) so this is the 3rd transformer lol. The 50v one was outputting 78v DC so couldn't take the risk with the AM882's.

Normally 50v would be spot on but I'm in a commercial unit and my voltage comes out 10v's higher than domestic in the UK which I hadn't factored in.

A big thank you to Clive S and Joe Harris on Mycncuk I couldn't have done it without you guys

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[john-100]

Hi Tutu

off load I would expect your transformers out put to be 5 or 6% high off load

the 45V output only applies when fully loaded transformer with a 230V mains input

( 250/230 ) x 1.06 x 45V = 51.8V ac

[small transformers about 10 to 20 VA can be 30 % or more high when off load ]


once rectified

the DC voltage across the capacitors will be 1.4142 x 51.8 = 73V DC

the DC voltage will drop several volts under load but it can be higher during regenerative breaking !!

John

PS

my domestic single phase supply is 242 to 248 V depending on the time of day