I want to test smps transformer (230v to 20v). Can I test it by giving 230v AC directly to the primary???.. (In fact I have tested it connecting to 230v AC but the MCB trips when it is tested, is it possible to test a SMPS transformer to connect directly to the AC ??) . Is the SMPS transformer is like normal step down transformer.. ???
It's a step down transformer operating at several 10 kHz. Your question suggests, that you don't have the means to test it, possibly except for measuring winding resistances and isolation.
The smps transformer is not normal step down transformer. Generally they operate at higher frequencies.The frequency of AC power is 50Hz/60HZ. Thats why in SMPS the AC power is first synchronized and converter to DC voltage and fed to the transformer along with some driver chip.
Putting a Pure SMPS transformer directly to AC power source may fry it almost immediately.