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???
02/21/05 08:13
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#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




List of 29 messages in thread
TopicAuthorDate
WEOT: Predicting thyristor firing angles            01/01/70 00:00      
   well..            01/01/70 00:00      
      Re: Well.            01/01/70 00:00      
         most likely            01/01/70 00:00      
   Graphs            01/01/70 00:00      
   Distortion of mains            01/01/70 00:00      
      Re: Distortion of mains            01/01/70 00:00      
         Only a guess...            01/01/70 00:00      
            Re: Only a guess.            01/01/70 00:00      
               Intelligent machine?            01/01/70 00:00      
                  Re: Intelligent Machine.            01/01/70 00:00      
                     Some averaging is needed            01/01/70 00:00      
                        Re: Averaging.            01/01/70 00:00      
                           More Details New Method.            01/01/70 00:00      
                           Could work, but have some averaging            01/01/70 00:00      
                              Precision Resistance welding?            01/01/70 00:00      
                                 Re: Precision Resistance welding?            01/01/70 00:00      
                                    Precision resistance welding            01/01/70 00:00      
                                    sounds like an app for multiprocessing            01/01/70 00:00      
                                       Re: Multiprocessing            01/01/70 00:00      
                                          multitasking/multiprocessing            01/01/70 00:00      
                              Re: Averaging.            01/01/70 00:00      
         Better Control            01/01/70 00:00      
            Re: Better Control.            01/01/70 00:00      
               Control System            01/01/70 00:00      
                  Difference in calculation & Actual Param            01/01/70 00:00      
                     Re:Diffrence in calculation and actual            01/01/70 00:00      
                        Single Cycle Welding            01/01/70 00:00      
                           RE: Differece In Cal & actual Parameters            01/01/70 00:00      

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