Re: Inductive load currents at varying voltages

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Spir Georges GHALI

@sturnbull720 said:
Just wondering if anyone can help me, I have recently come across a large voltage drop issue when a client is using a mig welder. When the welder is in operation at full load current it draws 26 amps (single phase load). The voltage at the outlet at no load is 242V and under full load current is 208V. The voltage drop is due to a pre-existing large run (over 50 metres) of 2.5mm2 twin and earth cable which is grossly under rated for its application. I am looking at upgrading the circuit cabling to larger CSA conductors which will overcome the voltage drop issue. My question is however, if the welder is drawing 26 amps at 208V, what will the current draw be at nominal voltage of approx 240V? I understand with a purely resistive load that, impedence remaining constant, as voltage decreases, current will do the same. I’m trying to avoid installing circuit wiring suitable for circuit length/voltage drop/load current, only to find out at nominal voltage the load will be considerably higher. Any information will help. Thanks


Dear ;

Normally, the voltage drop is from the source till the load, and the percentage at your case is around ” 14% ” ( too much ), so, is the measured value at the input points of welder or at the beginning of the 2.5mm² cable ? if at the input points of the welder, it’s better to measure it at the beginning of cable to decide if the changing this section will be enough or not.