Transformer clamp ammeter structure and working principle
Structure and principle
The clamp meter is essentially composed of a current transformer, a clamp wrench and a rectifier magnetoelectric instrument with reaction force.
The working principle of clamp meter is the same as that of transformer. The primary coil is the wire passing through the clamp-type iron core, which is equivalent to the primary coil of a transformer with one turn. This is a step-up transformer. The secondary coil and the ammeter for measurement form a secondary loop. When alternating current flows through the wire, it is this turn of the coil that produces an alternating magnetic field and an induced current in the secondary loop. The ratio of the current to the primary current is equivalent to the inverse ratio of the turns of the primary and secondary coils. The clamp ammeter is used to measure large current. If the current is not large enough, the number of turns of the primary conductor can be increased when it passes through the clamp ammeter, and the measured current can be divided by the number of turns.
The secondary winding of the through-core current transformer of the clamp ammeter is wound on the iron core and connected with the AC ammeter, and its primary winding is the measured wire passing through the center of the transformer. The 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-core transformer, so that it can clamp the measured conductor.
When measuring current, press the wrench, open the jaw, and place the current-carrying conductor to be measured in the middle of the through-hole current transformer. When alternating current passes through the conductor to be measured, the magnetic flux of alternating current induces current in the secondary winding of the transformer, which passes through the coil of the electromagnetic ammeter, causing the pointer to deflect, and indicating the measured current value on the dial scale.
After putting the measured wire into the window through the iron core button, pay attention to the good coincidence between the two faces of the jaw, and do not let other objects get in the middle;
The z small range of the clamp meter is 5A, and the display error will be larger when measuring a small current. This is that the electrified wire can be wound around the clamp meter for several weeks and then measured, and the obtained reading value is divided by the number of turns, which is the required result.
