On the question of how to connect the motor started by the star delta to start directly

The connection upstairs doesn't seem to be right?! The last thing you need is definitely the triangle start, or the turning distance will be insufficient, it should be u1v2, v1w2, w1u2

First of all, we must understand a problem, that is, there is no necessary connection between direct starting, star-delta starting and winding. The root of the problem is that the correct voltage is applied to the windings of the motor. In the case of direct start alone, the voltage rating on the nameplate is the voltage to be applied to each winding.

Method (applicable to all motors to be changed): 1. Check the nameplate: connection method (star?)

Triangle? ）；Rated voltage (440?) ,380？

Or 220V? 2. According to the connection method given on the nameplate, it is connected into a star shape, and vice versa is connected into a triangle. Note:

U1 and U2 are two ends of the same winding, V1, W2, W1, W2 are the same, star connection: U1, V1, W1 are connected (not connected to the external power supply), U2, V2, W2 are respectively connected to the external power line voltage (the voltage on the nameplate);

Triangle connection: the head and tail of each winding are connected, that is, U2 is connected to V1, V2 is connected to W1, and W2 is connected to V1, at this time there are only three endpoints left, and then they are connected to the line voltage (the voltage on the nameplate). 3. Remove the star delta control circuit, and directly connect the three terminals to the switch of the three-phase power supply (low-power motor) or to the terminal of the contactor (slightly high-power motor).

Please note: high-power motors cannot be changed lightly! According to the motor you mentioned, because it was used in the star triangle start, it is inferred that it should be a triangle connection.

Therefore, there will be no problem according to the "triangle joint" in 2.

If you need triangles, you need to connect u1u2, v1v2, and w1w2 together. As for the star, u2v2w2 is connected together.

Hello dear, long waiting! Star-delta starting noise source combustion is a more common starting method of three-phase asynchronous motor. In the star delta starting process, the winding of the motor will be connected into a star shape first, reduce the starting current and starting torque, and then connect the winding into a triangle after the motor reaches a certain speed, so that the motor can reach the rated operating state.

Therefore, the motor of the star delta wiring cannot be started directly, and it needs to be guided and switched through certain steps to run successfully. Star-delta start-up needs to be achieved through equipment and circuits such as main contactors, auxiliary contactors, timers and wiring cabinets. The specific steps are as follows:

1.Sequential wiring: connect the motor windings according to the star triangle wiring method.

2.Carry out no-load and load test run: in the star, carry out no-load and light-load start-up of the motor, check whether the motor rotates normally, and whether there is abnormal sound or vibration.

If everything is in order, a formal test can be carried out. 3.Switch to a triangle connection:

After a period of star-shaped operation, the control circuit switches to a triangle connection to make the motor work at the rated voltage and rated power, and obtains the required starting torque. At this stage, it is necessary to ensure the accuracy of the switching time to avoid motor overload or other problems. It should be noted that if the motor is overloaded, the switching time is inaccurate or the wiring is not in place, it may lead to motor start-up failure, damage, and even pose a threat to personal safety.

Triangle connection, normal operation, if reversed, just adjust two of the three lines of ABC.

If there is a nameplate or terminal symbol, generally the upper row of the terminal is U2V2W2, and the following is U1V1W1, the U1 and V2 of the multimeter are connected, and the V1W2 is connected to W2U2, and the U1-2 V1-2 W1-2 is connected in turn in order to form a triangle operation.

Precautions for Star-Delta motors

In the star angle start, these two connection methods are combined and used together, that is, the star connection method is used during start-up to achieve the purpose of step-down start and protect the power grid and motor. After starting, a triangle connection is used so that the motor works at the rated voltage. Usually this switching is done automatically by a specific control circuit, but it can also be done by PLC.

The required electrical components are, circuit breaker, fuse, contactor, relay, delay relay, etc., there are two main circuits for star angle starting, and the corresponding control loops are also different.

There is a diagram of the star triangle wiring circuit.

When the motor starts, connect the motor to a star-shaped wiring, and then reconnect the motor to a triangle wiring when the motor is successfully started (quickly switch through the double-throw switch); Star-delta start-up is a step-down start-up. The use of star-delta start-up can avoid the impact of motor start-up on the grid voltage is excessive, and it is generally required to use star-delta start when the power of the squirrel cage motor exceeds 10% of the rated power of the transformer.

After pressing the start button, the two contactors of the star-shaped connection are first engaged, and the motor runs in the star-shaped connection.

At the same time, the time relay is energized and the delay starts. As soon as the delay time is up, the two contactors of the star connection are released, the contactors of the triangle connection are engaged, and the motor runs in a triangular way, as long as it does not stop or power off, it has been running in this way.

The starting process is to first let the tail end of the motor be connected to the star, start, when the speed of the motor reaches 60%, and then change the star connection to the triangle connection through the contactor, which is his starting process

Explain the star-delta starting process of three-phase asynchronous motor, including the wiring of the on-site motor and distribution cabinet.

This Y-δ (star delta) starting method, the purpose is to reduce the starting current, reduce the harm to the power grid and electrical equipment, this method is only suitable for tens of kilowatts of small motors, such as large motors using the self-lotus transformer starting mode.

How to wire the Star-Delta starter motor: 1The connection method of star-delta starting is that when the motor starts, the U2, V2 and W2 of the three-phase winding are shorted together through the three groups of contacts of the star-shaped starting contactor, and the other end of the three-phase winding is connected to the three-phase power supply through the main contactor.

2.After the motor is started, the time relay in the control line acts, and the star contactor is disconnected at the same time, and the triangular contactor is engaged, and the three-phase winding is connected into a triangle to run, and the other end of the three-phase winding remains unchanged. 3.

The working principle is that when the triangle connection is connected, each phase winding bears 380V voltage, and when the star connection is connected, the two windings are connected in series to withstand 380V voltage, and the actual winding of each phase bears 220V voltage, which belongs to step-down start.

The 3-phase winding inside the motor, you can simply think of it as 3 wires, as shown in the picture above. The star or triangle connection is different according to the connection method, here it is marked with 14, 25, 36 three lines (you can also use u1u2, v1v2, w1w2 to mark). To 1 and 6 two heads together to connect the A phase, 3 and 5 two heads together to connect the C phase, 2 and 4 two heads to connect the B phase together, that is, the triangle connection method (do you see the image of a triangle?). , the same goes for star-shaped ones. The annotation and the definition of each terminal may not be the same, usually we can only see 6 heads in the motor terminal box, but in the end it is connected into a triangle or star, if you are interested, you can split the 6 heads with a multimeter, 6 wires are three wires that communicate in pairs. You look at the nameplate or requirements of the motor, and you can pick it up yourself.

y— Buck start control.

Press the start button SF, the time relay KT and the contactor KM2 are energized at the same time, the normally open main contact of KM2 is closed, the stator winding is connected into a star, the normally open auxiliary contact is closed, the normally open main contact of the contactor is closed, the stator is connected to the power supply, and the motor is in the star shape.

Start under the connection. A pair of normally open auxiliary contacts in KM1 are closed and self-locking. After a certain delay, the normally closed contact of KT is disconnected, KM2 is reset when power is off, and the contactor KM3 is energized and engaged. The normally open main contact of km3 wraps the stator.

Assemble into a triangle so that the motor is rated.

Figure 5-18 y— Step-down start control Normal operation at the voltage. The function of the normally closed auxiliary contact of KM3 in series with the button SF is: when the motor is operating normally, the normally closed contact is disconnected, cutting off the passage of KT and KM2, even if SF is pressed by mistake, KT and KM2 will not be energized, so as not to affect the normal operation of the circuit.

If you want to stop, press the stop button SS, the contactor KM1 and KM2 will be powered off and released at the same time, and the motor will stop rotating when it is disconnected from the power supply.