The Concepts together with Functions connected with Leakage Current Subir
Print View | Html View
Written by: usergirl
Total views: 25 |
Word Count: 603 |
Date: Sun, 8 Jan 2012 |
0 comments
In accordance with the Usa UL standards, the leakage present includes the capacitance coupling currents, plus they can conduct in the reachable part of household appliance. The leakage present consists of two components, one will be the carried out present I1 through the insulation resistance, another one will be the displacement present I2 through the capacitance. And capacitive reactance in the later on one is c=1/2πfc, it's inversely proportional to frequency, and the displacement present is proportionate to frequency. Hence, the leakage present increases using the increase of power frequency. Such as, when silicon-controlled rectifier supplies the power, its harmonic component will cause to boost the leakage present.
If you just check the insulation performance of a circuit or a hipot tester, the present must include the one which flow into the ground by insulation substance, also, it will need to also include the 1 which flow into the ground through the capacitance component (the component of distributive capacitance will be the capacitance 1) circuit of system. Longer route will form a larger circuit capability, and it will boost 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 current tester resistance measurement. Actually the measurement of insulation resistance is a kind of testing leakage current. The difference is that it's expressed by resistance. Yet, the formal measurement of leakage current is applied by AC voltage. Subsequently, leakage current also contains the capacitive component current.
During the voltage test, in order to protect the test equipment without damage and do the test in accordance with the required technical specifications, we also need to set a maximum current value which won't destroy the test equipment with the maximum electric field intensity. This present value is also called leakage present. Pay attention, this value is applied in the above specific situation. When the working power (or other power) goes with the insulation or impedance, it will produce the leakage current which has nothing to do with the working power. The leakage current tester is just used to measure the leakage present, and the input impedance stimulate the one of human body.
The operations of Leakage present tester are as follows:
First, plug hipot tester in, and switch on the power. The power indication will be on.
Second, select the power range, and press the button in the required present.
Third, select the leakage current alarm value.
4th, select the test of time.
5th, connect the target using the measure device. Start the leakage present tester. Boost test voltage to the insulation resistance tester working, voltage of 1.06 (or one.1 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 current 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 with 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 might converse the polarity by K, and select the greater value as the leakage current for the measured appliance.
I studied power supply for many years, manufactured electrical safety tester. Now focused on ac electronic load research.
Source: The Concepts together with Functions connected with Leakage Current Subir
http://www.financebusinessarticles.com
Rating: Not yet rated
