Examining the Internal Structure to Determine the Clamp Ammeter's Operating Principle
The clamp meter is mainly composed of an electromagnetic ammeter and a feed-through current transformer. The secondary winding of the core-through current transformer is wound on the iron core and connected to the AC ammeter, and its primary winding is the measured wire passing through the center of the transformer. When measuring the current, press the wrench, open the jaws, and place the measured current-carrying wire in the middle of the feed-through current transformer. A current is induced in the side winding, and the current passes through the coil of the electromagnetic ammeter, causing the pointer to deflect, and the measured current value is indicated on the dial scale. The clamp ammeter must be connected in series with the circuit under test.
In actual operation, the line has to be disconnected, which is obviously very inconvenient. The clamp clamp ammeter is a portable instrument that can directly measure the AC current of the circuit without disconnecting the circuit. It is very convenient to use in electrical maintenance and is widely used.
The clamp meter knob is actually a range selection switch, and the function of the wrench is to open and close the movable part of the core of the through-type transformer so that it can clamp the wire under test.
Common faults of clamp ammeter
(1) When measuring current or voltage, there is no indication for one or several gears, and the other gears are normal. The reason is that the fastening switch screw of the clamp meter is loose, or the connection wire on the branch switch is twisted. This kind of Faults are the most common, just connect the broken wire after opening the cover.
(2) The reading of the current gear is too small, and the reading of the voltage gear is normal. Most of the reasons are caused by poor contact of the jaws and too much magnetic flux leakage. The jaws should be corrected to make them in good contact. This failure is sometimes caused by a short circuit between windings. It is more troublesome at this time. Generally speaking, it needs to be rewound according to the original data, and aging treatment is also required.
(3) The readings of the current and voltage files are all low. This phenomenon often occurs on the internal magnetic clamp meter. The reason is that the magnet is demagnetized. Generally, it should be magnetized to solve it. It can also be solved by reducing the resistance connected in series with the branch circuit of the meter head. value is adjusted.
(4) One of the readings is inaccurate, and the corresponding resistance should be adjusted.
(5) The indication of the voltage level is normal, but there is no indication of all the current levels. Use a multimeter to check the primary wire switch and secondary winding to see if there is any abnormality.
(6) There are no indications at all. Check the rectifier diode, meter head, switch, and the connection with the clamp meter or related wiring for breaks.
