How to operate and use a clamp meter correctly
When using a clamp ammeter to detect current, be sure to clamp one conductor (wire) to be measured. If you clamp two (parallel wires), the current cannot be detected. In addition, when using the center (core) of the clamp ammeter to detect, the detection error is small .When checking the power consumption of home appliances, it is more convenient to use a line separator. Some line separators can amplify the detection current by 10 times, so the current below 1A can be amplified before detection. Use a DC clamp ammeter to detect the DC current. (DCA), if the current flows in the opposite direction, a negative number is displayed. This function can be used to detect whether the car's battery is in a charged or discharged state.
True valid value detection
The average value method clamp ammeter detects the average value of the sine wave through AC detection, and displays the value after amplifying 1.11 times (sinusoidal AC) as the effective value. Waveforms other than sine waves and skew waves with different waveform rates can also be detected. It is also displayed after being magnified 1.11 times, so there will be an indication error. Therefore, when detecting waveforms other than sine waves and distorted waves, please choose a clamp ammeter that can directly test the true effective value.
Leakage detection
Leakage detection is different from ordinary current detection. Two (single-phase 2-wire type) or three (single-phase 3-wire type, three-phase 3-wire type) must be clamped. The ground wire can also be clamped for detection. The insulation management method for detecting leakage current on low-voltage circuits has become the primary means of judgment. Since its confirmation (revision of technical standards for electrical equipment in 1997), it has been used in buildings and buildings that cannot be powered off. Factories gradually use leakage current clamp meters to detect leakage current.
The clamp meter is an instrument that combines current and ammeter. It is an important branch of digital. Its working principle is the same as measuring current. A clamp meter is a combination of a current transformer and an ammeter. The iron core of the current transformer can be opened when the wrench is tightened; the wire through which the measured current passes can pass through the open gap of the iron core without cutting it, and the iron core is closed when the wrench is released. The conductor of the circuit under test passing through the iron core becomes the primary coil of the current transformer, in which current is induced in the secondary coil. As a result, the ammeter connected to the secondary coil will have an indication to measure the current of the circuit under test.
The clamp meter is essentially composed of a current transformer, a clamp wrench and a rectifier magnetoelectric system with reaction force instrument.
A clamp meter works on the same principle as a transformer. The primary coil is a wire passing through the clamp-type iron core, which is equivalent to the primary coil of a 1-turn transformer. This is a step-up transformer. The secondary coil and the ammeter used for measurement form a secondary circuit. When an alternating current flows through the wire, it is this turn of the coil that generates an alternating magnetic field and an induced current in the secondary circuit. The ratio of the size of the current to the primary current is equivalent to the inverse ratio of the number of turns of the primary and secondary coils. . The clamp ammeter is used to measure large currents. If the current is not large enough, you can increase the number of turns of the primary conductor through the clamp meter and divide the measured current number by the number of turns.
The secondary winding of the core-type current transformer of the clamp ammeter is wound on the iron core and connected to the AC ammeter. Its primary winding is the conductor under test that passes through the center of the transformer. The knob is actually a range selection switch, and the function of the wrench is to open and close the movable part of the core of the through-core transformer so that it can clamp the wire under test.
