Makeshift Leakage Current Measurement Tool 

To get an amps to volts conversion ratio of 1, as this project did, the resistor value (in ohms) needs to be equal to the current transformer turns ratio. So you either need to know the transformer turns ratio, or measure it.

His tester produces 1 mV per mA of current, or 1 volt per amp. The burden resistor is 1500 ohms, so the output voltage is 1500 times the secondary current. In turn, this means that the secondary current must be 1/1500 of the primary current to make the overall conversion factor 1. So this current transformer secondary must have 1500 turns. If you buy a current transformer, you will know the ratio. If you take one out of a ELCB/GFCI as shown, you might have to measure the turns ratio by experiment to get the correct burden resistor.

ELCB = $10, Leakage Clamp meter = $600~$1000. I will test with toroid inductor

Either way, its still pretty freakin cheap/easy way to measure leakage !

You need to pay attention to the magnetic characteristics of the toroid core. You need a core that works well at 60 Hz, not one that works at 100 kHz. So the line filter inductors found near the 120/240 V input to the power supply are probably good, while the main step-down transformer likely has a ferrite core that won't work well. You also need a core big enough that it doesn't saturate at the current you're trying to measure. If you only want to measure 0-30 mA or so, that's not going to be a problem, but if you want to measure 10A or 20A of supply current with your current transformer the core will need to be large enough.

The current transformers (both the little one and the Fluke clamp meter) measure the difference in current between line and neutral. If there is no leakage, the line and neutral currents are exactly the same and their magnetic fields cancel. In the video, there is no normal load and no neutral current, but the two test setups produce controlled current between line and ground. The ground current bypasses the current transformer, so the line current produces a magnetic field that is measured by the current transformers.

전극의 면적과 전극간 물의 길이에 따라 달라집니다.

MrPreva С наступающим Новым Годом!