How to use the leakage clamp ammeter
Principle of Leakage Clamp Ammeter:
Leakage current clamp meter is mainly composed of impedance conversion, range conversion, AC and DC conversion, amplification, indication device and so on. Some also have overcurrent protection, acoustic and visual alarm circuit and test voltage regulation device, the indication device is divided into analogue and digital two kinds. According to the UL standard, the leakage current is including capacitive coupling current, including the current that can be conducted from the accessible part of the household appliances. Leakage current consists of two parts, one part is through the insulation resistance of the conduction current I1; the other part is through the distribution of capacitance displacement current I2, the latter capacitance resistance for XC = 1/2pfc and power supply frequency is inversely proportional to the distribution of capacitance current with the frequency increases, so the leakage current with the power supply frequency increases. For example, the harmonic component of the power supply with a thyristor increases the leakage current.
If the test is a circuit or a system of insulation, the current in addition to all the insulating material through the current into the earth (or conductive part of the circuit), should also include through the circuit or the system of capacitive devices (distributed capacitance can be regarded as capacitive devices) and into the earth's current. Longer wiring will form a larger distribution capacity, increasing the leakage current, which should be especially noted in the ungrounded system.
Leakage clamp-on ammeter Precautions:
1. The principle of leakage current measurement and insulation resistance is basically the same, the measurement of insulation resistance is actually also a leakage current, only in the form of resistance expressed. However, the formal measurement of leakage current is applied to the AC voltage, thus, the leakage current component contains a capacitive component of the current.
2. In the withstand voltage test, in order to protect the test equipment and according to the specifications of the test, it is also necessary to determine a * high electric field intensity without destroying the equipment under test (insulating material) allowed to flow through the equipment under test (insulating material) the maximum value of the current, this current is usually also known as the leakage current, but the essentials are only in the specific occasions mentioned above. Please note the difference.
3. Leakage current is actually the current that flows through an insulated part of an electrical line or equipment in the absence of faults and applied voltages. Therefore, it is one of the important signs to measure the insulation of electrical appliances, dare to be the main indicator of product safety performance.
4. Leakage current tester is used to measure the working power of electrical appliances (or other power sources) through the insulation or distribution parameter impedance generated by the leakage current has nothing to do with the work of the impedance of the input impedance simulation of the human body's impedance.
Leakage clamp-on ammeter operation method:
1, plug in the power supply, turn on the power switch, the power indicator light;
2, select the power range, press the desired current button;
3, select the leakage current alarm value;
4, select the test time;
5, the object under test into the measurement end, start the instrument, the test voltage to the object under test rated operating voltage 1.06 times (or 1.1 times), switch the phase conversion switch, respectively, read the secondary readings, select the value of large readings leakage current value. When the conversion switch K and zero line connected, the tester is sampled by the middle line and shell leakage current; when K and phase line connected, the test is phase line and shell leakage current between.
6. It must be noted that: K and zero line connected or K and phase line connected, the leakage current is not necessarily the same. This is because the location of insulation weaknesses in household appliances is random. Therefore, the leakage current test should be converted by K polarity, take the larger of these values as the leakage current value of the electric appliance under test.
