I have been working on a transformer for a long time.I bought a transformer to use for a. 1.5kva inverter.The transformer has an isolator attatched under the block top.It is an undetachable metal blocks which can not be piecesed like ordinary transformers.One just have to unscrew the top to pull out the former.After winding the primary side with a gauge 20 copper coil for 450turns and gauge 13 for 48 turns on the secondary side,the transformer cuts fuse and produces a very low current when I applied it to my inverter.Where have I gone wrong?I want to produce 230 volts for my appliances.Could the fault come from the transformer?I've been winding transformers before.Please someone help me.

 

What is the crossection of the core? What is the material? What frequency is your inverter using?