Selection Guide for Clamp Ammeter
(1) Firstly, it should be clear whether the measured current is AC or DC. The clamp Ammeter of rectification system is only suitable for measuring power frequency current with low waveform distortion and small frequency change, otherwise, it will produce large measurement error. For the clamp Ammeter of electromagnetic system, because the deflection property of the movable part of its measuring mechanism is independent of the polarity of current, it can be used to measure both AC current and DC current, but its accuracy is usually low. The accuracy of clamp Ammeter mainly includes 2.5, 3 and 5 levels, which should be selected according to the technical requirements of measurement and the actual situation.
(2) For digital clamp Ammeter, the reading of the measurement result is intuitive and convenient, and the measurement function has also been expanded to measure resistance, diode, voltage, active power, reactive power, power factor, frequency and other parameters. However, the digital clamp Ammeter is not perfect. When the electromagnetic interference in the measurement is serious, the displayed measurement results may have discrete jumps, which makes it difficult to confirm the actual current value; If a pointer type clamp Ammeter is used, its response to strong electromagnetic field interference is relatively slow due to the damping effect of the magnetoelectric system mechanical meter head itself, which at best means that the needle has a small swing, its indication range is relatively intuitive, and reading is relatively easy.
The Method of Measuring Small Current with Clamp Ammeter
The clamp Ammeter has the advantage of measuring current without cutting off the circuit. However, due to its low accuracy, there is a significant error during measurement. Especially when measuring currents below 5A, the error often far exceeds the allowable range value.
In order to make up for this defect of clamp Ammeter, the following methods can be used when measuring small current.
1. Wrap the wire a few turns first
Wrap the measured wire around the clamp Ammeter for several turns, and then put it into the clamp of the clamp Ammeter for measurement.
2. Calculate current value
Calculate the measured current value according to the following formula to obtain the actual current value
I real=I measured/n
In the formula, I measurement - the current value measured after a few turns of winding;
N - Number of wire winding coils.
