The leakage current constant is: Leakage current I=kUC.
The requirement in the leakage current constant standard is that the protective earthing device protects the user from hazardous contact voltages in the event of faults or short-circuits in electrical equipment.
To ensure this basic function, the current on the protective ground wire must be limited, which is why most product safety standards include provisions for leakage current measurement and limitation. This is explained in the product safety standard EN 60950 I L for office equipment and IT equipment.
Basic Leakage Current Detection Principle:
The very small current that flows through a semiconductor PN junction at cutoff. The current flows from D to S only after D-S is set in forward bias, G-S is reverse biased and the conducting channel is open. But in reality, due to the presence of free electrons, the attachment of free electrons to SIO2 and N+, leads to leakage current in D-S.
Power switching power supply in order to reduce interference, in accordance with national standards, must be equipped with EMI filter circuit. Due to the EMI circuitry, so that the switching power supply in the connected power to ground there is a small current, which is the leakage current. If not grounded, the computer's case will be 110 volts to the ground, with a numb feeling when touched by hand, while the computer work will also have an impact.
Capacitor media can not be absolutely non-conductive, when the capacitor plus DC voltage, the capacitor will have a leakage current. If the leakage current is too large, the capacitor will heat up and be damaged. In addition to electrolytic capacitors, other capacitors leakage current is very small, so the insulation resistance parameter to indicate its insulation performance; and electrolytic capacitors due to leakage is larger, so the leakage current to indicate its insulation performance (proportional to the capacity).