The motor is the most common electrical component in our industrial control, many students are not very clear about the motor wiring method, in the end how to connect, the Internet to check is also confused, today we will come to the motor on the nameplate connection method to explain.
Motor nameplate description
From the right part of the nameplate, it can be seen that there are two kinds of △ type 220V and Y type 380V. Many students in this piece must have doubts, because to the Internet to check Y-delta start is a buck start, and the motor marked Y380V to △ 220V boost is just the opposite, what is going on? Let's look at the VOLTS voltage level on the left has 380V/220V, which corresponds to the voltage level of the input power supply, such as our industrial electricity is three-phase 380V, and there are three-phase 110V, 220V, 440V, 660V and other voltage levels in foreign countries. We analyze the relationship between the marking, connection method and voltage level of the motor in the above figure.
First of all, let's look at the difference between the Y-type connection method and the △ connection method, these two connection diagrams have been seen by everyone, whether on the motor or various data will see, the motor windings have three groups corresponding to the three lines U, V, W and 6 lines, the head U1 and the tail U2, then U1U2 is composed of a line, sometimes the tail is represented by X, Y, Z as shown above. The Y-type connection method is to connect the tails of the three wires (U2, V2, W2) in a piece to form a neutral point similar to the transformer, and the triangle is the tail of the first wire and the head of the second wire (U2 and V1, V2 and W1, W2 and U1), so that the end is connected to form a triangle shape.
Motors are connected in different ways
If it is now a three-phase power supply with a voltage of 380V, the corresponding phase voltage of each phase is 220V, which everyone should understand, then if according to the Y-type connection method, the phase voltage of each winding of the motor is equal to the power supply phase voltage of 220V, because the tail of each winding is a neutral point 0V is equivalent to connecting a fire wire and a zero wire; look at the △ type connection method, the phase voltage of the motor winding is equal to the line voltage of the power supply 380V, because there is no midline point equivalent to each winding is connected to two fire wires. We do not consider the power factor and efficiency, the amount of power of the three-phase motor is equal to:
Power, voltage, current relationship
We analyze the normal operation of the motor and the comparison of the winding current that has just started, the motor is still as the parameter in the figure above, assuming that the △ starting current is I△, then the Y-type starting current is 1/3 I△, when the speed rises, for the winding current under the same power P:
380V voltage for the Y-type connection method, the use of three-phase 380V industrial electricity, starting current 1/3I△, normal current is equal to P/ (3 * 220)
For the △ type connection method, the use of three-phase 380V industrial electricity, starting current I△, normal current is equal to P/ (3 * 380)
220V voltage using Y-type connection method, using three-phase 220V industrial electricity, starting current 1/ (1.7 * 3) I △, normal current is equal to P / (3 * 129)
Using △ type connection method, using three-phase 220V industrial electricity, starting current 1/ (1.7) I△, normal current is equal to P / (3 * 220)
440V voltage using Y-type connection method, using three-phase 440V industrial electricity, starting current 1.17/3I△, normal current is equal to P/(3*258)
Using △ type connection method, using three-phase 440V industrial power, starting current 1.17 I△, normal current is equal to P/ (3 * 440)
In summary, for a motor, if the grid level is higher than the rated level of the motor, the △ type connection method cannot be used, and the starting current is large; if the grid level is lower than the motor, the Y-type connection method cannot be used, and the current is too large during normal operation.
In addition, for the understanding of △ 220V and Y380V on the motor nameplate, that is, if the three-phase industrial electricity is 380V small-power motor, the Y-type connection method can be used for high-power motors can be used △ type connection method (using Y-delta to reduce the starting current), if the three-phase industrial electricity is 220V, the △ type connection method must be selected, and the Y type cannot be used. Note that the voltages indicated in the motor are line voltages and not phase voltages.
What's wrong with that can be pointed out in the comments below.
Disclaimer: The content and pictures in this article come from the Internet, please contact to delete the infringement.