Single-phase voltage is 220 volts. The voltage between the phase line and the neutral line. The two phases are A and B or C of the phase line, and the phase voltage between them is 380. Common electrical appliances are 380 electric welders. The three-phase voltage between AC is 380 volts. Electrical appliances are three-phase 380 volt motors or equipment. Convert AC power into DC power. Motor capacitors cannot replace exciters. The exciter is a stator coil that can rotate by supplying power to the rotor coil at the same time.
Three-phase electricity is mainly used as a power source for motors, that is, loads that need to rotate. Because the three phases of three-phase electricity are 120 degrees apart, the rotor will not get stuckImagine that one pedal of a bicycle is stopped at the bottom and the other pedal is at the
highest position. This is because the force of the foot pedaling the bicycle is downward, so it may be "stuck" (when the direction of the foot force is consistent with the connection line of the two pedals), or it may turn backwards, and it may not be guaranteed to turn forward first. It is necessary to change the pedal angle with your feet.
Three-phase electricity is to form this "angle", otherwise, people would not have to deal with such a complicated three-phase electricity.
There is a difference between three-phase electricity and single-phase electricity.
Three-phase electricity is used for industrial production, with a voltage of 360V.
Ordinary residents use single-phase electricity, with a voltage of 220V.
Three-phase power supply has four wires, three of which are 220v live wires and one is a neutral wire. Using any live wire and neutral wire together is what we usually call commercial power supply and 220v power supply. However, for the balance of three-phase power, it is recommended to connect the corresponding load when possible.
A generator that can generate equal amplitude, equal frequency, and a phase difference of 120 potential is called a three-phase generator.
A three-phase generator as a power supply is called a three-phase power supply.
A circuit powered by a three-phase power supply is called a three-phase circuit;
u, v, and w are called three phases, and the phase-to-phase voltage is the line voltage, which is 380v;
The voltage between the phase line and the center line is called the phase voltage, which is 220v.
1. The difference between three-phase power supply and single-phase power supply: The power generated by the generator is three-phase. Each phase of the three-phase power supply and its neutral point can form a single-phase circuit to provide power to users. Note that the AC circuit here cannot be called positive or negative, but should be called line end (live wire in civil power supply) and neutral line (zero line in civil power supply).
2. According to regulations, the neutral point of the 380-volt (three-phase) civil power supply should not be grounded at the user end (grounded at the transformer end, considering that the point higher than the power supply voltage cannot be caused by floating point, the user end grounding and transformer end grounding have a certain resistance on the ground). The power supply method is a loop composed of live wire and neutral wire (neutral lead), and the single-phase three-core power socket is connected to the ground wire. This is to take into account the realization of the leakage protector function. (The working principle of the leakage protector is: if the human body touches the line end of the power supply, that is, the live wire, or the internal leakage of the electrical equipment, then the current will flow from the live wire through the shell of the human body's live electrical equipment into the earth, instead of flowing through the neutral wire, and the current of the live wire and the neutral wire will be unequal. After the leakage protector detects this current difference, it will immediately trip to protect the safety of people and electrical appliances. Generally speaking, this differential current is selected in tens of milliamperes.) If, if the neutral point of the power supply is directly grounded (not allowed in civil electrical construction), the leakage protector will lose its function and cannot protect people and electrical equipment from short circuits.
Three-phase electricity generally costs 380 yuan, four wires, three are live wires, and one is a neutral wire. 30-volt electricity is used as industrial electricity.
Two-phase electricity is generally 220 volts, with two wires, one is a live wire and one is a neutral wire. 220-volt electricity is used for civil use
There is a difference. Three-phase power supply is 380 volts. Single-phase power supply is 220 volts. The so-called three-phase power supply refers to three-phase live wires, the voltage between adjacent live wires is 380v V, and there is no neutral line. Therefore, three-phase power can only be applied when the three-phase load is the same (for example, a three-phase motor). At this time, since the sum of the current vectors of the three-phase power supply is 0 (the three-phase power supply is 120 degrees from each other, so the sum is 0), there is no need for a neutral line (equivalent to a neutral line). The three-phase asynchronous motor consists of a stator and a rotor.
Two-phase motors refer to motors with two-phase windings. Two-phase motors are divided into two categories: drive motors and servo motors. Most of the (single-phase) asynchronous motors used in household appliances and small appliances belong to two-phase drive motors. The control uses a two-phase servo motor. The two-phase windings of the stator are the excitation winding and the control winding, which are 90 degrees apart in space.
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