On Wednesday 28 July 2021 15:25:01 Chris Albertson wrote: > Do you really need to worry about inrush tripping the breaker? > 1) If the DC supply is the old linear type, it will have a very large > filter capacitor and supply peak loads without a large AC draw. The > trick is to turn on the supply and then the motor a second later.
Now, imagine that supply consists of 4 toroid transformers each capable of developing the nominally 63 volts plus and minus, for a 1 kw analog audio amp. and the filter caps are 6 in each supply of 9200 uf at 65 volts, and each transformer is treated as a single supply. wired two in parallel and two tall for a combined voltage of around 126 volts and 220800 uf. Plug that into a 30 amp breaker and flip the switch. clunkiest switch you ever heard because that 30 amp breaker went down like a shotgun on the first half cycle of power, essentially simultaneous with the click of the switch. So I hit the junkbox and come up with two 40 amp SSR's and a 50 ohm 200 watt resistor, added a couple time delays controlled by hal and driven by the F2 state such that the 50 ohm is in series with the supply line for the first 4 seconds and is shorted after that. Now it runs fine on a 15 amp breaker, but will trip it if I ignore the motors chirping because the pwm-servo is set to about 17 amps but it takes several seconds, so I settled for a 20 amp in that slot. And for Ralph's problem with the Washington inspectors, I suspect they are reading the rules wrong, here they don't care about the load, the only thing they checked outside of the box was the ground wiring to the rods. And for lack of any other pressing duties, helped me bore 2 holes thru about 8" of green concrete the required 6 feet apart to make it meet code. After he ok'd hooking up the drop so we had power to run the hammerdrill. Cheers Chris, Gene Heskett -- "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) If we desire respect for the law, we must first make the law respectable. - Louis D. Brandeis Genes Web page <http://geneslinuxbox.net:6309/gene> _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
