??? 02/21/05 08:13 Read: times |
#88040 - RE: Differece In Cal & actual Parameters Responding to: ???'s previous message |
Mr. Prahalad you have misunderstood what i have said in
last paragraph. Please read it again At least you can measure main voltage& frequency and correct firing angle accordingly. U can apply some methodlog to caluc equilvalent load at diffir firing angle by applying low value ac mains voltage. or more simply apply 5 V stepped down AC main & calculated RMS current for 4-5 firing angle value around calculated one and then measure AC mains values and calculate Equivalent RMS at that AC mians value at those firing angle and then use firing angle for which these Equivalent RMS value (from 5 V ac mains) matches desired RMS. Beacuse even if you calibare machine at manu time , parameter effecting RMS value will vary at actual place. I am not saying that you measure AC voltage through step down transformer but apply stepped down(through transformer) 5-6 V AC mains for at 4-5 firing angle around your calculated angle for welding and measure resulting current and then interpolated that for RMS current for actual AC main voltage and correct firing angle for full main voltage . See following RMS current req = 4 Amp theoratical acalculated firing angle for (4 Amp RMS) = 110 deg use a step down transfor of say 1:25 ie for 225 AC mains output will be 10 V. Apply this 10 V AC for 100 , 105 , 110 , 115 , 120 deg firing angle for actual weld and measure RMS curret F.angle---Measured RMS curr---Interploated RMS for Full AC Main (FA)------(MRMS)--------------(IRMS = MRMS * 25) step ratio 1:25 120------110 mamp-----------2.75 Amp 115------130 mamp-----------3.25 Amp 110------150 mamp-----------3.75 Amp 105------155 mamp-----------3.875 100------160 mamp-----------4.0 Amp So you can use 100 deg firing angle for weld at Full AC Mains |