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Introduction to the working principle of dc power supply and negative polarity
- Apr 23, 2018 -

This paper mainly introduces the working principle of positive and negative poles of dc power supply, and the application of dc power supply in inverter welding machine.

Dc power supply has both positive and negative electrodes, the anode potential of the high and low potential of the cathode, after the two electrodes and the circuit is connected, able to maintain a constant potential difference between the circuit at both ends, thus in the external circuit formed by the positive to the negative current.

Basic technical parameters of dc power supply: dc general input voltage :AC220V plus or minus 10% 50Hz + 5Hz, output ripple and noise: Cv is less than or equal to 1mvrms CC less than 5mARms.

The difference between the water level and the water level can not maintain the steady water flow, and the constant water level can be maintained by the water pump continuously from the low point to the high place. Similarly, the electrostatic field generated by electric charge alone cannot sustain stable constant current, and by using dc power supply, can use the electrostatic interactions (referred to as "the electrostatic force") by making positive charge by the cathode potential low internal returns to the potential of high power are desperately, in order to maintain the potential difference between two electrodes, forming a steady current. Therefore, a dc power supply is an energy conversion device that converts other forms of energy into a power supply circuit to maintain the steady flow of current.

The non-static electricity in the dc power supply is pointed to the positive pole by the negative pole. When the dc power supply is connected with the external circuit, the current is formed from the positive electrode to the negative electrode in the external circuit (external circuit) due to the electric field force. In the internal (internal circuit) of the power supply, the non-electrostatic force causes the current to flow from the negative electrode to the positive pole, thus causing the flow of the charge to form a closed loop.

When the positive and negative poles of the dc power supply are not connected, the power supply is in the state of breaking (open circuit), when the potential difference between the two electrodes of the power supply is equal to the electromotive force of the power supply. In the break state, there is no conversion between non-electric energy and electrical energy. When the load resistance on the poles of the actuators to a power to form a closed loop, by the power within the electric current to flow from the cathode to the anode, at this point, the power supplied by the power E I equal to the power of U/I (U is a potential difference) between the positive and negative power supply and internal resistance loss in thermal power R0I sum, E I = U I R0I. Therefore, when the power supply is supplied to the load resistor, the potential difference between the two poles is U = e-r0i.

In order to obtain high dc voltage, the dc power supply is often used in series. The total electromotive force is the sum of the electromotive force of each power supply, and the total internal resistance is also the sum of the internal resistance of each power source. Due to the increase of internal resistance, it can only be used for circuits with small current strength. In order to obtain larger current strength, electromotive force, such as dc power may be connected in parallel, then the total electromotive force is the electromotive force of a single power supply, total internal resistance of the power of the internal resistance in parallel.

Dc power supply can provide stable arc and smooth droplet transition. The electric arc is ignited, and the dc arc can keep burning continuously. When the ac power welding is adopted, due to the change of current and voltage direction, and the arc of each second is extinguished and reignited 120 times, the arc cannot continuously and steadily burn. In the case of low welding current, the dc arc has a good wetting effect on the molten weld metal, and it can regulate the weld size, so it is very suitable for welding thin pieces. Dc power supply is more suitable than ac power supply for welding and vertical welding, because dc arc is shorter.