Is there a difference in speed between the same motor, star connection and triangle connection? The public is right, and so is the old woman. If you just ask the same question, you will have different opinions. Besides, people who engage in technology generally have a little temperament. If they are wrong, they can rely on real experience to turn defeat into victory.
The star connection of three-phase asynchronous motor does not change the mechanical structure of the motor itself, but only changes the voltage (star connection: the line voltage is three times the square root of the phase voltage), and the winding of the motor bears the phase voltage.
So what determines the speed of three-phase asynchronous motor?
Frequency, magnetic pole logarithm.
It can be seen that star connection or angle connection has no effect on speed.
So does changing the voltage have an effect on the motor?
Yes: torque.
The load is large, the required torque is large, and the voltage is not enough. It may be possible to maintain power by increasing the current. This is the most ideal state.
However, if the connection mode of unmarked motor is changed casually (both star connection and angle connection are acceptable), then the winding quality and technical specifications of motor design are limited to star connection (or angle connection), which has a great influence on torque. If the load is light, there is little difference. If the load is heavy, there is not only a big difference, but it may also be burned.
What's the difference between triangle connection and star connection of three-phase motor power supply with the same line voltage? Both star connection and triangle connection refer to the winding connection of the motor itself. Star connection refers to connecting the three-phase ends of the motor winding together, and the first end of the three-phase is the power supply end.
Triangular connection refers to connecting three-phase windings end to end, and three endpoints are power ends;
No matter what kind of connection, there must be a three-phase sinusoidal AC power supply with a phase difference of 120 degrees, which cannot be replaced by 220V V V.
Because the voltage of three-phase live wires (A, B, C) of three-phase alternating current is 220V, but the phase difference between them is 120 degrees, and the voltage difference between three phases is 380V, it is irreplaceable to use three live wires in the same phase.
Basically, it is 1.732 times, which is three times that of the root.
What is the difference between the triangle connection and the star connection of the same three-phase asynchronous motor? Friend, the triangle connection and the star connection of the same motor use different voltages to change the connection, that is to say, the triangle connection supplies 380 volts and the star connection uses 660 volts. The speed and power consumption are the same, and there is no change.
Three-phase asynchronous motor star connection and triangle connection, specifically how to connect three-phase asynchronous motor star connection is to connect three terminals in the upper row of terminals, and the lower row of three terminals is a three-phase power supply. Triangulation is to connect two corresponding terminals above and below the terminal.
The Y-series motors with star triangle are all connected in a star shape below 3KW and above 4KW. The current decreases, the voltage increases, the voltage decreases, and the current increases. Star line voltage = phase voltage of cubic root sign. River line current = three times the root number, the phase current torque is small, and the torque is large-the star and triangle connections of three-phase motors are fixed in design. You can't change it casually-the star can be made into 3-phase 4-wire with center line, which can reduce higher harmonics, mainly the 3rd harmonic and circulation, and is safer in the case of asymmetric short circuit-if the motor nameplate is marked with star connection, the voltage and current borne by the winding will exceed the rated value, which will burn out the motor winding-for example, the three-phase 380V star connection is changed to triangle connection, and its adaptive voltage is 220V for three phases. The triangle connection is changed to star connection, and its adaptive voltage is 660 V-high power of motor. In order to avoid the influence of excessive starting current on the line, triangle wiring is generally changed to star wiring for starting, and then converted back to triangle wiring after starting.
Three-phase asynchronous motors below 3KW and 4KW are connected in a star shape, and those below 4KW are connected in a triangle shape. These motors have been connected at the factory. If it is necessary to change the connection, please follow the following methods: open the junction box of the motor, remove the lead metal plate on the series terminal, and connect the three terminals together with the lead plate. The motor wires of the following three terminals are connected in a star shape; If two terminals in the longitudinal direction are connected with lead plates in turn and connected with motor wires, it is a triangular connection. Be careful not to lose small items such as screws during operation. Before closing the junction box, check whether there is any overlap between terminals and whether there are any items missing in the junction box. Close the junction box after inspection.
In fact, there are related wiring diagrams on the motor nameplate.
What are the advantages and disadvantages of star connection and triangle connection of three-phase asynchronous motor? Advantages of star connection: no damage to load balance, disadvantages: large resistance.
Advantages of triangle connection: small resistance, disadvantages: different windings or one of them is broken, which will destroy the load balance of three phases.