Selection of clamp type ammeters
1. For information on the selection of clamp ammeters, please log in to: Transmission and Distribution Equipment Network
(1) Firstly, it should be clear whether the measured current is AC or DC. The rectifier clamp type ammeter is only suitable for measuring power frequency currents with low waveform distortion and little frequency change, otherwise it will result in significant measurement errors. For electromagnetic clamp ammeters, the deflection property of the movable part of the measuring mechanism is independent of the polarity of the current. Therefore, it can be used to measure both AC current and DC current, but the accuracy is usually relatively low. The accuracy of clamp type ammeters mainly includes levels 2.5, 3, and 5, and should be selected based on measurement technical requirements and actual situations.
(2) For digital clamp ammeters, the reading of their measurement results is intuitive and convenient, and the measurement functions have also been expanded to measure parameters such as resistance, diode, voltage, active power, reactive power, power factor, frequency, etc. However, digital clamp ammeters are not perfect. When electromagnetic interference in measurement situations is severe, the displayed measurement results may experience discrete jumps, making it difficult to confirm the actual current value; If a pointer type clamp type ammeter is used, due to the damping effect of the magnetoelectric mechanical meter head itself, its response to strong electromagnetic field interference is relatively slow. At best, the meter needle produces a small amplitude of oscillation, and its reading range is relatively intuitive, making it relatively easy to read.
2. Inspection of clamp ammeter before use
Focus on checking whether the insulation material (rubber or plastic) on the jaws has fallen off or broken; The integrity of the entire casing, including the gauge head glass, directly affects the measurement and involves the performance of the instrument; Also check if the zero point is correct. If the watch needle is not at the zero point, it can be adjusted through the adjustment mechanism; For multi-purpose clamp type ammeters, the test wires and bars should also be checked for damage, with good conductivity and insulation required; For digital clamp ammeters, it is also necessary to check if the battery level inside the meter is sufficient, and update it if it is insufficient.
