What we usually call three-phase energy (three-phase power supply) is transmitted in civil buildings using a three-phase five-wire system (protective earthing system). There are three-phase wires (marked A and B when the phases). are clearly marked on the drawing. , VS ; Under normal circumstances, the three phases are marked L1, L2 and L3 respectively. Here 1, 2 and 3 must be indicated.) The phase colors correspond to A(L1)**. , B(L2) green and C(L3) respectively red, a neutral wire (marked N, light blue) and a protective wire (earth wire, marked PE, yellow and green); buildings or transformers to the main power distribution. The cabinet part adopts three-phase four-wire system (protected zero connection system) for transmission, with the above three phases and one neutral wire (PEN wire, phase color is black); high voltage transmission system, athree-phase three-wire system is used (only three-phase line) or two-line transmission (only two-phase lines) when connecting to three-phase equipment, there are three-phase lines and protection; line (i.e. PE line).
What are the four wires of the car generator plug?
The generator has three phases and four wires (three lights and one zero), and the cabinet distribution in has three phases and five wires (three lights and one zero), the zero light to the electrical distribution cabinet behind the light are directly earthed.
If the distribution box and the generator are off, the distribution box and the generator must share the ground wire, that is, the generator shell, the generator box shell distribution and generator zero line (neutral line) are connected at the same time, the ground wire of the distribution box is the same as that of the neutral line and the shellmetal of the distribution box, so no generator is needed.
If the distribution cabinet is far from the generator, the distribution cabinet must be grounded according to regulations, as well as the distribution cabinet ground wire and the metal shell of the distribution cabinet.
Detailed information:
380V/220V low voltage power distribution system can be divided into: IT system, TT system and TN system according to different forms of protective grounding.
The electrical neutral point of a computer system is isolated or high impedance grounded, while the metal enclosure of electrical equipment is directly grounded. Namely: an electrical power system protected by earth, formerly called a three-phase, three-wire system.
The neutral point ofTT system power supply is directly grounded; the metal shell of the electrical equipment is also directly grounded, regardless of the neutral grounding of the power supply. Protective earthing in old three-phase four-wire power system.
The TN system is in the three-phase, four-wire low-voltage electrical network of 380/220 V. The neutral point of the transformer or generator is directly grounded. The metal shell of electrical equipment that is not grounded. charged during normal operation is connected to the neutral point of the power supply through a common protection line. Click to log in. That is, no protection is provided for the old three-phase four-wire power system.
The neutral power point of the TN system is directly grounded and has an outgoing neutral wire. TN system is divided into TN-c system, systemTN-s and TN-c-s system depending on the shape of its protection line.
The four wires of the car generator plugThe lines are: live wire, ground wire, power transmission line and power indicator line energy production.
1. One is live wire (medium thickness, red or warm color).
2. One is ground wire (medium thickness, black or cool color).
3. One is the power transmission line, that is, the electricity generated by the generator is sent back to the battery for storage (the thicker wire, ** or red).
4. The last one is the power generation indicator wire (a relatively thin wire, if the generator is generating electricity it will be transmitted to the dashboard and the battery light on the dashboard will turn off).
In the low speed range, due to the low speed of the generator, the serial output of the windingsThree-phase ments increase the generator output voltage, significantly improving the generator's low-speed charging performance. .
In the high speed range, as the generator speed increases, the inductive reactance of the three-phase windings connected in series increases, the internal voltage drop increases, and the armature reaction strengthens, which which makes the output voltage drops. At this time, due to the small internal voltage drop of the original three-phase windings A, B and C, the induced current generated is relatively large, ensuring high-speed power output.
The working principle of the integrated alternator
When the external circuit feeds the excitation winding through the brush, a magnetic field is generated, causing the poles to become magnetized claws in N poles and S poles. As the rotor rotates, the magnetic flux changes alternately in the stat windinggold. According to the principle of electromagnetic induction, it can be seen that an alternating induced electromotive force is generated in the three-phase winding of the stator. This is how an alternator produces electricity.
The main motor (i.e. motor) drives the rotor of the synchronous generator excited by direct current to rotate at a speed n (rpm), and the stator winding three-phase induces an alternating potential. If the stator winding is connected to an electrical load, the motor will produce alternating current. The alternating current will be converted to direct current through the bridge rectifier inside the generator and output from the output terminal.
The alternator is divided into two parts: the stator winding and the rotor winding. The three-phase stator winding is distributed across the housing at an electrical angle difference of 120 degrees to each other. is composed of two polar claws. When the windingof the rotor is connected to direct current, it is excited and the two polar claws form the N pole and the S pole.
The magnetic field lines start from the N pole, enter the stator core through the air gap then return to the adjacent S pole. Once the rotor turns, the rotor windings cut the magnetic lines of force, generating a sinusoidal electromotive force with a mutual difference of 120 electrical degrees in the stator windings, i.e. three-phase alternating current, then converted into direct current output via the rectifier element composed of diodes.
When the switch is closed, the battery first supplies current. The circuit is:
Battery positive pole → charging indicator light → regulator contact → field winding → ground → battery negative pole. At this time, the charging light will light up because there is current flowing through it.
However, after starting the engine, asre as the speed of the generator increases, the voltage across the generator also continues to increase. When the generator output voltage is equal to the battery voltage, the potentials of the generator terminals “B” and “D” are equal. At this time, the charging indicator light turns off due to the potential difference between the two ends. is zero.
Indicates that the generator is operating normally and that the excitation current is provided by the generator itself. The three-phase AC electromotive force generated by the three-phase windings of the generator is rectified by the diode, and then produces DC power to power the load and charge the battery.
Reference for the above content: Baidu Encyclopedia-Car Generator