Generator bits & bobs

Question

Can someone advise me what specification of diode bridge rectifiers (11.) and diode (42.) I need for for the generator in my camper. And would appreciate if you can tell me how the three different windings in the stator can produce different voltage outputs - one winding produces 12v and the other 230v. The centre winding with capacitor is to excite the field I presume.

kkazem · Answer

I'm not sure what you mean by " tell me how the three different windings in the stator can produce different voltage outputs". I'll do my best as a power electronics engineer. The alternator has different isolated windings with differing numbers of turns. The output voltage for each winding is proportional to the number of turns. Therefore, for a 230V vs a 12V output, the turns would be 230/12 =19.166 times (approximately) more turns on the 230V winding than the 12V. An alternator typically has a three-phase AC output which gets full-wave rectified by a 6-diode, 3-phase diode bridge. But in your case it looks different. I don't see a 3-phase winding. The non-230VAC winding appears to have a tapped output and is used for 12 VDC (after a strange rectification circuit) and for an AC hour meter for the generator. The 230VAC winding is the high-power output for your AC loads and appears to be single phase. 
 For DIODE (42), I would agree that a 6A , 100V is probably OK, but I don't really have enough information on it. You might want to to go a 200V PIV diode for that. For the bridge, DIODE BRIDGE (11), I believe the 35A, 400V recommended by kmikemoo is fine (probably overkill, but better safe than sorry).

Generator bits & bobs

Top Replies