After contacting many customers who buy motors, I collected some questions and related answers from the technology that customers usually ask.Maybe you will also encounter this kind of confusion when using or replacing motors.When buying a motor, there are several keywords, such as ordinary motor, aluminum housing motor, variable frequency motor, three-phase asynchronous motor, vertical installation, horizontal installation, motor power, voltage, DC motor, AC motor, etc. What you need to know when buying .
1.Why is the leakage circuit breaker easy to trip when using the inverter?
This is because the output waveform of the inverter contains high-order harmonics, and the motor and the cable between the inverter and the motor will generate leakage current. The leakage current is much larger than when the motor is driven by the power frequency, so this phenomenon occurs.
The leakage current on the output side of the inverter operation is about 3 times that of the power frequency operation, plus the leakage current of the motor, etc., the operating current of the leakage protector should be greater than 10 times the leakage current at the power frequency.
2. What kind of motor is an AC variable frequency motor?
To put it simply, frequency conversion technology is used in the control of AC motors.AC variable frequency motor is actually a kind of motor that relies on adjusting the AC frequency to adjust the speed. The adjustment of the AC frequency depends on the frequency converter. The motor itself does not frequency conversion. In many less demanding occasions, it is to use an ordinary motor and a frequency converter to adjust the speed as AC. Frequency conversion motor is used.
3.Can a single-phase 220v inverter change into a three-phase 380v?
是不可以。变频器本身是不能升压的，更不能从单相220v变出三相380v。从理论上这是可行的，用变压器将单相220V升高为380V，然后单相380V转换为三相380V。
4. The belt driven by the high-power motor has a reducer connected to the motor. What is the role of the reducer here?
The purpose of the reducer can be briefly summarized:
Decrease the speed and increase the output torque at the same time. The torque output ratio is based on the motor output multiplied by the deceleration pen, but be careful not to exceed the rated torque of the gearbox.
5. Answer the reason for the slow speed when the motor starts?
If the speed is only slow when starting, it will be normal after starting.It may be that the starting capacitor is not matched, or the motor design is originally like this (designed according to the site), or it may be that the starting time is too long due to factors such as excessive load resistance.
If the speed is still slow after starting, the problem may be insufficient voltage, mismatched capacitors, large rotation resistance, etc.
6.60. What should I pay attention to when a 50HZ motor is used on a XNUMXHZ power supply?
This is because the current frequency of the motor is lower than the design frequency. To reduce the no-load back-EMF generated during rotation and increase the no-load current, causing damage to the motor, the no-load voltage is required to be reduced.
In the variable frequency speed regulation technology, the frequency of the motor and the stator voltage are changed at the same time.That is, the frequency drops, and the voltage also drops at the same time, so that the motor will not over-current and will get the ideal operating effect.
7. How can I know if the motor is in star/delta connection?
Wye connection is that one end of the three-phase winding is connected, and the other end is connected to the three-phase power supply, shaped like the letter "Y"; the delta connection is that the three-phase windings are connected end to end to form a "△" shape, and the top of the triangle is then connected to three phases power supply.
Their phase voltages are different. Generally, the rated voltage of the motor in star connection is 220V, and the rated voltage of delta connection is 380V.The connection method is generally marked on the inside and outside of the cover of the junction box, and different connection methods correspond to different power supply voltages.
8.How does the number of poles of the motor affect its selection?
Motors currently have 2/4/6/8 class motors, and the number of special-purpose motors may be higher.The more the number of pole pairs of the motor, the lower the speed of the motor, but the greater its torque; when selecting a motor, you have to consider how much starting torque is required for the load. For example, the starting torque with load is higher than that with no load. The torque required for starting is large. If it is a high-power and large-load starting, a step-down starting (or star-delta starting) should also be considered; as for the problem of matching the speed of the load after determining the number of pole pairs of the motor, you can consider using different The diameter of the belt pulley is used for transmission or the transmission gear (gear box) is used to match.If the power requirement of the load cannot be reached after the motor is driven by belt or gear after determining the number of pole pairs of the motor, then the power of the motor must be considered.
