Technical points to consider when using the clamp-on ammeter
1. Safety requirements
(1) We often need to measure the current value of low-voltage wires or equipment in practice. In the distribution of low-voltage busbar and its electrical components in the measurement of current, the general low-voltage busbar row of interline distance is not large enough, some of the clamp-on ammeter body size is large, the measurement of open jaws may cause a short-circuit between phases or grounding, if the measurement of the personnel's posture is unstable or arm shake, it is more likely to occur accidents. Therefore, according to the actual conditions of the site, before the measurement, the use of qualified insulating materials to isolate the busbar and electrical components to the phase, and should pay attention to not touching other charged parts.
(2) in measuring the current of bare wires, if the distance between different phase wires and wires and ground is small, if the jaw insulation or insulation sleeve has been damaged, it is easy to cause phase to phase, phase to phase, phase to ground short circuit accidents. Therefore, it is usually stipulated that the clamp ammeter is not allowed to measure the current of the bare conductor, if it must be measured, the bare conductor insulation should be done to isolate the preparatory work to prevent accidents.
(3) For multi-purpose clamp ammeter, the functions shall not be used at the same time, for example, in the measurement of current, you can not measure the voltage at the same time, for ** considerations, the test line must be pulled down from the clamp ammeter.
(4) in the measurement site, a variety of equipment should be in order, all parts of the body of the measurement personnel and the electrified body must be maintained between the distance is large enough, at least not less than the safety distance (low-voltage system ** distance of 0.1m - 0.3m). Readings, often involuntarily lowered or explore the waist, this time to pay special attention to the limbs, especially the head and the charged part of the safety distance between.
2, accuracy requirements
(1) measuring current, clamp-on ammeter gear selection should be appropriate, * good so that the needle falls to the scale of 1/3 or more of the scale, because the deflection angle of the needle is too small, the scale value is not easy to distinguish, affecting the accuracy of the measurement.
(2) The measured wire should be placed as far as possible in the jaws of the central position, such as the measured wire is too oblique, the measured current in the jaws of the core of the magnetic induction intensity generated by the jaws will occur more substantial changes, directly affecting the accuracy of the measurement, generally due to the measured wire in the jaws of the improper position caused by the measurement error can be up to 2% -5%.
(3) In order to make accurate readings, should make the iron core jaws of the two sides of the tightly closed. If you hear the electromagnetic noise emitted by the jaws or grasp the clamp ammeter hand has a slight vibration of the feeling that the jaws end face combination is not tight, this time should be reopened, close the jaws of a time; if the murmur still exists, you should check the jaws end face with or without dirt or rust, if there should be ** clean until the jaws combined with a good so far.
(4) for digital clamp ammeter, although in the use of the battery before had checked the battery power, but in the measurement process, should also pay attention to the battery power situation at any time, if the battery voltage is found to be insufficient (such as the emergence of low-voltage symbols), must be in the replacement of batteries and then continue to measure; if there is electromagnetic interference at the measurement site, will inevitably interfere with the measurement of the normal course of the measurement, it should try to exclude the interference. Can correctly read the measurement data, but also directly related to the accuracy of the measurement.
