Contraindications and Countermeasures for Using Clamp Ammeter
1. Do not check or verify before use
In order to ensure the accuracy of the measurement, ensure the personal safety of the measurement operator, and ensure the normal operation of the electrical system under test, it is required to check before using the clamp ammeter. The main inspection contents are: whether the case and head glass are damaged and Cracks; whether the insulating material on the jaw iron core and the handle is intact; whether the pointer of the meter head is flexible and whether it is at zero position. If not, you can turn the mechanical zero position mechanism to adjust to zero position. The watch is used as a good watch. In addition to the above visual inspection, a test should be carried out by taking the clamp-on meter to be used to confirm that there is a current flowing, of the same type as that for which the meter is to be used, and on conductors familiar with the approximate number of currents. Test and confirm that it is normal according to the measurement results before it can be put into use.
2. Ignore the type of the measured current and choose the phenotype at will
The type of clamp ammeter used for measurement must be compatible with the type of current to be measured. If the frequency and waveform of the measured current are relatively standardized power frequency currents, the general clamp ammeter can do the job. If there is a high requirement for measurement accuracy, it is more appropriate to choose a transformer clamp ammeter, because its The accuracy level is slightly higher than that of the electromagnetic clamp ammeter; if the measured DC current, power frequency current with large waveform distortion, low frequency or large fluctuations rotor current), it is necessary to select the electromagnetic clamp ammeter. Otherwise, the current may not be measured, or may be measured, but the measurement result is not reliable.
3. Use ordinary clamp ammeter to measure high voltage current
Ordinary clamp ammeters cannot meet the safety requirements for measuring high-voltage currents because of their structure and insulating materials. In addition, most of the high-voltage wires are bare wires. It is very difficult and dangerous to insulate the measured part under the charged state. Once the wire hits the iron core of the jaw, or the high voltage directly discharges the instrument and the person, the consequences will be disastrous. Therefore, ordinary clamp ammeters can only be used for current measurement of 380V and below circuits, and are strictly prohibited for current measurement of high-voltage circuits.
4. Reckless selection and handling of measurement points
The selection and handling of measurement points must be treated with caution, which is related to the safety of operators and electrical equipment. It should be selected on the wire with insulating sheath as much as possible, and it is best to choose on the line section with good insulation; when measuring the current of low-voltage fuse or low-voltage busbar arranged horizontally, it is necessary to use an insulating board with good insulation performance to connect the fuse or busbar. Phase isolation is carried out to avoid short circuit and electric shock accidents.
5. Weak security awareness and inadequate countermeasures
Some surveyors have weak safety awareness, credulously trust some experience, lack effective preventive measures, and have a fluke mentality. This attitude is extremely dangerous. During the measurement operation, insulated shoes and gloves should be worn. The insulated shoes, insulated gloves and work clothes should be in a dry state, and the body posture should be kept stable. The human body should keep a sufficient safe distance from other charged bodies.
