Products leakage current is no fault in the case of the applied voltage, the electrical insulation between the metal parts with, or between live parts and between the parts ground through the surrounding medium or the insulating surface formed current is called leakage current . According to the U.S. UL standards, including leakage current is capacitively coupled currents, including, from household appliances accessible parts conduction current product attributes leakage current tester mainly by impedance transformation, range conversion, AC-DC conversion, amplification, indicating devices and other components . Some also have overcurrent protection, sound and light alarm circuit and the test voltage regulating device, which indicates the device of analog and digital two. Other Description leakage current consists of two parts, one part is conducting current through the insulation resistance of the I1; another part is distributed capacitive displacement current I2, which is capacitive reactance XC = 1/2pfc inversely proportional to frequency and power, distributed capacitive current with frequency increased with increasing frequency so the leakage current increases with the power increases. For example: a thyristor power supply, the harmonic components of the leakage current increases. If the assessment is a circuit or insulation performance of a system, then the current through the insulating material in addition to including all flows into the ground (or circuit external conductive part) of the current, but also through the circuit or system, including the capacitive device ( distributed capacitance can be regarded as a capacitive device) and a current into the earth. Long wiring will form a large volume of distribution, increasing the leakage current, which is in ungrounded systems should pay particular attention. Transactions that EFT payments, payment and delivery.