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Azur Electronics

I bought this Power Transformer on eBay with local collection as it weighs 22kg. It was described as an isolating transformer which is a useful addition to my workshop when working on equipment with live mains voltages exposed.

April 2009

Taking the covers off revealed 4 large capacitors inside so definitely not an isolating transformer!

Powering-up on a Variac and measuring primary voltage and current, and secondary voltage with different loads soon showed that this is a constant voltage transformer.

The secondary has an extra winding which together with the capacitors forms a resonant circuit. This provides a stabilised output voltage of 240Vac and 220Vac from an input voltage of between 70Vac and 260Vac approximately. Very useful if you are working in an area with unregulated mains voltages.

A write-up on this technique is on Wikipedia.

This Constant Voltage Transformer has been tested and operates over a surprisingly wide input voltage range. The stabilised output is rated at 500VA with a PF of 1.0 at 50Hz.

Manufacturer's details are: Advance Type TCVN 500/44; Input Vac 190-260V; Output Vac 220-240V. Weight 22kg. Dimensions: 150mm Width x 210mm Height x 270mm Depth.

As I have no use for a CVT it will be for sale. NOW SOLD.