It's different for different power line frequencies. A 100 watt core at 60 Hz will be larger in size by 60/50 for a 50 Hz power line.Then there is a rule-of-thumb (something like X va/kg). Maybe 50?
Compare the size and what you do know with stuff available in a distributors catalog. If you can identify a manufacturer and part number go to the manufacturers web site.my transformer is giving 17 vac output at secondary when primary is connected to 230 vac
how can we find out current withstanding capacity of this transformer theoretically & practically.
i want to use it for making dc power supply.
there is no identification mark of mfger nor its part no. on the transformer.The practical method is to look up the part number and the manufacturer and ask them.
One fellow posted and deleted a suggestion about loading the secondary until you see a 5% drop in voltage, but I understand why he deleted. Transformer design is not very predictable from one purpose to another. Size has a lot to do with it. Tiny transformers will have more voltage drop under load than large transformers. The only thing I can contribute is that the basic principle where I worked at one time was that we had 20 watt cores, 50 watt cores, 500 watt cores, etc. I could order any set of secondary windings I wanted after I added up the wattage I needed. The weight of the copper wire would be the same for any given core, fully utilized. So, the weight is the clue. How much does it weigh? Do you have another which weighs about the same and has proper labels?
The overall lamination size LxWxH ? Photo?there is no identification mark of mfger nor its part no. on the transformer.
as regards to core size (nylon bobbin) is 1" x 1 1/2"
If you have the technology I used in 1974, that would indicate an EI core with a 1.5 inch stack of one inch (center leg) laminations...or the other way...a 1 inch stack of 1.5 inch laminations. Look for a similar transformer and read its label to find the wattage the core can carry.as regards to core size (nylon bobbin) is 1" x 1 1/2"
there is no identification mark of mfger nor its part no. on the transformer.The practical method is to look up the part number and the manufacturer and ask them.
One fellow posted and deleted a suggestion about loading the secondary until you see a 5% drop in voltage, but I understand why he deleted. Transformer design is not very predictable from one purpose to another. Size has a lot to do with it. Tiny transformers will have more voltage drop under load than large transformers. The only thing I can contribute is that the basic principle where I worked at one time was that we had 20 watt cores, 50 watt cores, 500 watt cores, etc. I could order any set of secondary windings I wanted after I added up the wattage I needed. The weight of the copper wire would be the same for any given core, fully utilized. So, the weight is the clue. How much does it weigh? Do you have another which weighs about the same and has proper labels?
L 3" X W 2 cm X H 2 1/2"The overall lamination size LxWxH ? Photo?
Max.
Mix of metric and Imp? I assume that is 3" x 1" x 2 1/2"?L 3" X W 2 cm X H 2 1/2"
Congratulations on achieving step one. Now do step two. Find a similar size transformer with proper labels and discover the wattage it is designed to transfer from the primary to the secondary.L 3" X W 2 cm X H 2 1/2"