The principle of the current of the core bar of the AC welding machine

Principle: The current and voltage are stepped-down by the three-phase main transformer, rectified by the thyristor components, and the output current is controlled by changing the phase of the thyristor trigger angle. The current signal is taken from the shunt at the DC output end of the rectifier as a negative feedback signal of the current, and as the DC output current increases, the negative feedback also increases, the conduction angle of the thyristor decreases, and the output current and voltage decrease, so as to obtain the external characteristics of the decrease.

The thrust circuit is when the output terminal voltage is lower than 15V, so that the output current increases, especially when the short circuit, the external characteristics of external drag are formed, so that the welding rod is not easy to stick. The arc striking circuit is to increase the given voltage for a short time every time the arc starts, so that the arc current is larger and the arc is easy to start.

From the above description, it can be known that the circuit is in a short-circuit state when the arc of electric welding starts, the voltage drops sharply, and the current needs to be very large; After the arc starts, the arc should be stabilized, at this time, the solution of the welding rod and the tank is still in a short-circuit transition state, the voltage is still dropping, and the current is still large; After the transition is completed, it is in a normal welding state, the voltage rises and the current drops.

The iron core is called a reactor, which mainly adjusts the air gap of the reactor core to adjust the welding current, which mainly changes the inductance of the reactor.

The AC welding machine consists of two coils, a static core and a moving core.

The primary coil is connected to the incoming power, and the secondary coil is connected to the output solder handle and ground wire. The two coils are not connected.

The static iron is a static iron window set by the wire package, (which is composed of silicon steel sheets,) and the moving iron is in the middle of the static iron. When powering the primary wire pack, a magnetic field will be formed because it is set on the static iron, and because the secondary package is also on the static iron, the voltage is induced back by the magnetic field, that is, the welding voltage.

The moving iron in the middle is to change its position to adjust the current size, it plays a role in blocking the magnetic track system, and the moving iron will block the magnetic field system, so it will change the secondary voltage, so that the current becomes smaller.

The track of the moving iron is made of copper because copper does not reverse magnetism and will not affect the current.

The AC welding machine is actually a step-down transformer: the number of turns of the secondary winding is small, the cross-sectional area of the wire is large, and low voltage and high current can be obtained in the secondary stage.

The principle of action of the moving iron core for the secondary current:

The moving iron creates a bypass in the transformer's magnetic circuit. Changing the position of the moving iron can change the magnitude of the magnetic flux through this bypass, which also changes the magnitude of the magnetic flux through the secondary winding, thereby changing the output voltage of the secondary and obtaining different welding currents.