The particular Concepts together with Operations connected with Leakage Present Eprouver
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Written by: usergirl
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Date: Fri, 6 Jan 2012 |
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In accordance with the Usa UL requirements, the leakage present includes the capacitance coupling currents, plus they can perform in the reachable part of home appliance. The leakage present consists of two components, 1 is the carried out present I1 with the insulation resistance, another one will be the displacement present I2 with the capacitance. And capacitive reactance in the later on 1 is c=1/2πfc, it's inversely proportional to frequency, and the displacement current is proportionate to frequency. So, the leakage present increases with the increase of power frequency. Such as, when silicon-controlled rectifier supplies the power, its harmonic component will cause to enhance the leakage current.
If you just check the insulation resistance tester of a circuit or a system, the current ought to include the one which flow into the ground by insulation substance, plus, it should also include the one which flow into the ground with the capacitance component (the component of distributive capacitance will be the capacitance one) circuit of system. Longer route will form a larger circuit capability, and it will raise the leakage current, which we ought to pay more attention in the ineffective grounded systems.
The principle of measuring leakage current is basically the same as the leakage present tester resistance measurement. To put it accurately the measurement of insulation resistance is a sort of testing leakage present. The difference is that it's expressed by resistance. Yet, the formal measurement of leakage present is applied by AC voltage. Thus, leakage current also contains the capacitive component present.
During the voltage test, in order to protect the test equipment without damage and do the test according to the required technical specifications, we also need to set a maximum present value which won't destroy the test equipment with the maximum electric field intensity. This current value is also called leakage current. Pay attention, this value is applied in the above specific situation. When the working power (or other power) goes through the insulation or impedance, it will produce the leakage present which has nothing to cope with the working power. The leakage current tester is just used to measure the leakage present, and the input impedance stimulate the 1 of human body.
The functions of Leakage current tester are as follows:
First, plug in, and switch on the power. The power indication will be on.
Second, choose the hipot tester, and press the button in the required present.
Third, select the leakage current alarm value.
4th, select the test of time.
Fifth, connect the target using the measure device. Start the leakage current tester. Boost test voltage to the rated working, voltage of one.06 (or one.one times) for measured object. When shifting the phase switch, record the readings for two times. Select the bigger value as the leakage present. When switch K on to connect the zero line, the value of tester will be the leakage present between the median line and the shell. When switch K on to the phase line, the value of tester will be the leakage present between the phase line and the shell. Well noted, when ac electronic load is connected with zero line or using the phase line, the leakage current is not always the same, because the insulation weakness positions of home appliances are random. Therefore, doing the leakage present test, we ought to converse the polarity by K, and select the greater value as the leakage present for the measured appliance.
I studied power supply for many years, manufactured electrical safety tester. Now focused on ac electronic load research.
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