16-12-2011, 07:21 PM
Thanks Luke.
Not wishing to tell my granny how to suck eggs - as the saying goes - but in addition to Alistair's suggestion, I would try testing each on some sort of suitable resistive load first - to measure the voltage drop, no-load to full-load, and the temperature rise of each at full-load. So what to use as a load? An old single-bar electric fire or a kettle (with water in it!) spring to mind: each are typically 1 Kw. rating. In use, you may find a problem with the switch-on surge blowing the mains supply fuse or tripping a breaker. In which case, I would wire a large power resistor in series with the transformer primary with a shorting switch across it: a 100-watt lamp springs to mind. Power the transformer up with the switch open for a second or two, then close the switch. The resistor prevents the mains supply from seeing what is virtually a dead short for that brief interval.
As for usage, what obviously springs to mind is to provide an isolated supply for the test bench. I wouldn't have thought that supplying 230v.a.c. to the 220v primary will cause any problems - and you'll get 230v.a.c. out, too. As for the switch-on surge problem in this application, a suitable mains-powered relay that switches the surge-limiting resistor should make a suitable automatic surge limiter. Alternatively, fit a delayed-action breaker in the supply.
Al.
Not wishing to tell my granny how to suck eggs - as the saying goes - but in addition to Alistair's suggestion, I would try testing each on some sort of suitable resistive load first - to measure the voltage drop, no-load to full-load, and the temperature rise of each at full-load. So what to use as a load? An old single-bar electric fire or a kettle (with water in it!) spring to mind: each are typically 1 Kw. rating. In use, you may find a problem with the switch-on surge blowing the mains supply fuse or tripping a breaker. In which case, I would wire a large power resistor in series with the transformer primary with a shorting switch across it: a 100-watt lamp springs to mind. Power the transformer up with the switch open for a second or two, then close the switch. The resistor prevents the mains supply from seeing what is virtually a dead short for that brief interval.
As for usage, what obviously springs to mind is to provide an isolated supply for the test bench. I wouldn't have thought that supplying 230v.a.c. to the 220v primary will cause any problems - and you'll get 230v.a.c. out, too. As for the switch-on surge problem in this application, a suitable mains-powered relay that switches the surge-limiting resistor should make a suitable automatic surge limiter. Alternatively, fit a delayed-action breaker in the supply.
Al.
