Leakage Current: The Part of EMC No One Talks About
It is just never about EMCHi Reader, EMC is a big topic, but it not the only one that can stop you from selling your device. Yes, you read it right. EMC is just ONE of the areas. There is also safety. Unfortunately, there are some interdependencies Modifications to pass safety tests can impact EMC and viceversa An example of it: leakage current and conducted emissions The leakage current is the current that can flow from your system to earth. There is a maximum amount of leakage current allowed. Why? Because when humans touch your system, the current will flow through their bodies This limit is generally low: 3.5 mA for industrial devices, 0.1mA for medical ones What has the current leakage to do with EMC? To limit conducted emissions, we use filters. These filters are a combination of inductors and capacitors. Capacitors are connected between lines (X) and between each line and earth (Y). Capacitors conduct alternate electricity. Then, in AC systems, these Y capacitors will make circulate some current to the earth. That current is limited by safety standards (for safety reasons). Your responsibility as a designer is to not exceed the safety limits Hints:
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