Common faults and solutions of clamp meters
There are two types of clamp ammeters, high voltage and low voltage, which are used to directly measure the current in the line without disconnecting the line. How to use it:
(1) When using a high-voltage clamp meter, pay attention to the voltage level of the clamp ammeter. It is strictly forbidden to use a low-voltage clamp meter to measure the current of a high-voltage circuit. When measuring with a high-voltage clamp meter, it should be operated by two people. Non-duty personnel should also fill in the second work ticket when measuring. They should wear insulating gloves and stand on the insulating pad when measuring. They should not touch other equipment to prevent short circuit or grounding.
(2) When observing the time of the meter, special attention should be paid to keeping a safe distance between the head and the live parts. The distance between any part of the human body and the live body shall not be less than the entire length of the clamp meter.
(3) When measuring on a high-voltage circuit, it is prohibited to use wires from the clamp-type ammeter to another meter for measurement. When measuring the current of each phase of a high-voltage cable, the distance between the cable heads should be more than 300mm and the insulation should be good. The measurement can only be carried out when it is deemed convenient.
(4) When measuring the current of low-voltage fusible fuses or horizontally arranged low-voltage busbars, each phase fusible fuse or busbar should be protected and isolated with insulating materials before measurement to avoid short circuit between phases.
(5) When one phase of the cable is grounded, measurement is strictly prohibited. Prevent the occurrence of ground breakdown explosion due to the low insulation level of the cable head, which may endanger personal safety.
(6) After the measurement of the clamp ammeter is completed, pull the switch to the maximum range to avoid inadvertent overcurrent the next time it is used; and it should be stored in a dry room.
Clamp ammeter solution
(1) When measuring current or voltage, one or several gears have no indication, while other gears have normal indications. The reason is that the fastening switch screw of the clamp meter is loose, or the connection on its branch switch is twisted. This kind of fault is the most common. Just connect the broken wire after opening the cover.
(2) The reading in the current range is too small, but the reading in the voltage range is normal. The reason is mostly caused by poor contact of the jaws and too much magnetic leakage. The jaws should be corrected to make good contact. This kind of fault is sometimes caused by a short circuit between windings, which is more troublesome at this time. Generally, it is said that the winding must be re-wound according to the original data and must be aged.
(3) The readings in the current and voltage ranges are both low. This phenomenon often occurs on internal magnetic clamp meters. The reason is that the magnet is demagnetized, which should generally be solved by magnetizing it, or it can be adjusted by reducing the resistance value in series with the meter branch.
(4) If one of the readings is inaccurate, the corresponding resistance should be adjusted.
(5) The voltage range indication is normal, but the current range has no indication at all. Use a multimeter to check the primary switch and secondary winding to see if there are any abnormalities.
(6) All without instructions. The rectifier diode, meter head, switch, and wiring connected to or related to the clamp meter should be checked for breaks.
