Basic introduction to clamp ammeter
A clamp ammeter 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 gap opened by the iron core without being cut off, and the iron core is closed when the wrench is released.
Usually, when measuring the current with an ordinary ammeter, it is necessary to cut off the circuit and stop the circuit before connecting the ammeter for measurement. This is very troublesome, and sometimes the motor in normal operation does not allow this. At this time, it is much more convenient to use a clamp ammeter, which can measure the current without cutting off the circuit.
How to use the clamp ammeter
When using a clamp ammeter to detect the current, be sure to clamp a measured wire (wire). If two (parallel wires) are clamped, the current cannot be detected. In addition, when the center (core) of the clamp ammeter is used for detection, the detection error is small .When checking the power consumption of home appliances, it is more convenient to use a line splitter. Some line splitters 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, it will display a negative number. This function can be used to detect whether the car's battery is in a charging state or a discharging state.
True RMS detection
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The clamp ammeter of the average value method detects the average value of the sine wave through AC detection, and displays the value after amplifying 1.11 times (sine wave AC) as an effective value. It is also displayed after being enlarged by 1.11 times, so there will be an indication error. Therefore, when detecting waveforms other than sine waves and crooked waves, please use a clamp-on ammeter that can directly test the true RMS value.
Leakage detection
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Leakage detection is different from the usual current detection, two (single-phase 2-wire type) or three (single-phase 3-wire type, three-phase 3-wire type) must be clamped. It can also clamp the grounding wire for detection. The insulation management method of detecting leakage current on low-voltage circuits has become the primary means of judgment. Since it was confirmed (revision of electrical equipment technical standards in 1997), it has been used in buildings and The factory gradually adopts the leakage current clamp meter to detect.
Tips for buying clamp meters
1: detection object
Choose the model according to different detection objects, AC current, DC current, or leakage current;
2: Detectable conductor specifications
According to the testing site, there are different specifications from 21mm diameter to 53mm diameter.
3: Is true value detection necessary?
The clamp ammeter using the average value mode cannot correctly detect the non-sinusoidal circuit such as the motor and the circuit of the transformer. The clamp ammeter of the true effective value mode should be used to detect this circuit.
4: Other functions
Not only can detect the current, but also a model that integrates the detection function and record output.
The clamp ammeter is called clamp meter for short. Its working part is mainly composed of an electromagnetic ammeter and a feed-through current transformer. The core of the core-through current transformer is made into a movable opening and is shaped like a clamp, so it is called a clamp ammeter. It is a portable instrument that can directly measure the AC current of the circuit without disconnecting the circuit. It is very convenient to use in electrical maintenance and widely used.
