Which is better, a clamp meter or a multimeter? Difference between clamp meters and multimeters
★ Clamp meter is divided into mechanical pointer clamp meter and digital clamp meter. Its biggest advantage is that it can be measured without disconnecting the measured line, the size of the current in the measurement line.
No matter what form of clamp meter clamp, generally only measure the work of the AC current, there are also some dedicated to measuring DC current clamp ammeter. Now more popular digital clamp meter is shown below.
In order to ensure the accuracy and safety of the measurement, should be used before the clamp ammeter for the following checks.
① Appearance check: there should be no damage and other defects, in particular, pay attention to the jaws should be closed tightly, the core part of the iron should be free of rust, no dirt.
② If the mechanical pointer clamp meter, the pointer should point to "0", otherwise it should be adjusted to "0" position.
③ Estimate the size of the measured current, select the appropriate gear. Selection of the principle of gear is: adjusted in greater than the measured value, and and close to the block.
Measurement of open jaws, the measured wire clamped into the jaws, close the jaws, the needle deflection, you can read out the measured current value. Readings should be made as far as possible before the clamp ammeter table level (mechanical pointer clamp meter), digital clamp meter does not matter.
★Matters to be noted in the measurement of clamp-on ammeter
①Test should be loaded with gloves (insulated gloves into clean and dry gloves), if necessary, should be set up a guardian.
② need to change gear when measuring, should first exit the wire from the jaws, shift and then clamp into the wire measurement.
③ The voltage of the measured wire should not exceed the voltage level of the clamp meter.
④ Poor insulation and bare wire is prohibited to use the clamp meter measurement.
⑤ When measuring, pay attention to keep a safe distance from the nearby electrically charged bodies, and care should be taken not to cause phase-to-phase short-circuit and phase-to-ground short-circuit.
⑥ High temperature environment is not suitable for measuring line current. Strong magnetic fields should not be measured near the external magnetic field on the measurement of the value of the impact is very large, clamp-on ammeter should not be in the busbar and large-capacity motors, transformers and other high-current load equipment next to the measurement, should be changed to a place to measure, in order to reduce the magnetic field caused by the error of the short-circuit.
⑦ wet places and thunderstorms should not be measured, because the clamp meter must be hand-held direct measurement, the operation of electrical equipment, measurement of clamp ammeter jaws, handles and measurement of personnel's hands must be kept clean and dry.
⑧ clamp ammeter measurement of non-work amount of current error. Clamp ammeter principle of operation determines the amount of rate to be used in the provisions of the clamp meter in addition to measuring sinusoidal current, the measurement of other waveforms of the current will produce errors, generally odd harmonic waveform than even spectral waveform error, especially the 3rd harmonic error is the largest, the clamp ammeter to measure the half-wave rectifier current, the error is also larger.
⑨ after use should be block position in the current of the highest block, with a table set into the table set, stored in a dry, dust-free, non-corrosive gases and not subject to vibration of the place.
⑩ can not measure high-voltage current, the voltage of the circuit to be measured can not exceed the rated voltage of the clamp-on ammeter. Clamp-on ammeter can not measure high-voltage electrical equipment.
