Hydraulic motor "difficulty" big answer, Dalan motor to help you get it all!

After contacting many customers who purchased the motor, Dalan Motor collected some questions from the usual customers and related answers. You may also experience this confusion when using a hydraulic motor or replacing a hydraulic motor. Don't worry, Dalan Motor Xiaobian will give you one by one.

1. Why is the leakage circuit breaker tripping easily when using the inverter?

This is because the output waveform of the inverter contains higher harmonics, and the cable between the motor and the inverter and the motor generates leakage current. This leakage current is much larger than that of the power frequency drive motor, so this phenomenon occurs.

The leakage current on the output side of the inverter is about three times that of the power frequency operation. In addition to the leakage current of the motor, the operating current of the selected leakage protector should be greater than 10 times of the leakage current at the power frequency.

2. I want to do the motor frequency conversion speed regulation experiment, can the ordinary motor realize the frequency conversion speed regulation? Still have to buy a variable frequency motor?

To do the motor frequency conversion speed control experiment with an ordinary AC motor.

The DC motor can also realize frequency conversion. For example, the current DC inverter air conditioner: it converts the power frequency AC power into a DC power supply and sends it to the power module. The module is controlled by the control signal sent by the microcomputer, and the AC output frequency is different from the module output. The controlled DC power is sent to the DC motor of the compressor to control the displacement of the compressor, thereby achieving "frequency control".

3. What kind of motor is an AC variable frequency motor?

Simply put, the frequency conversion technology is used in the control of the AC motor. The AC variable frequency motor is actually a motor that adjusts the frequency of the alternating current to adjust the frequency of the alternating current. The frequency of the alternating current depends on the frequency converter. The motor itself does not convert the frequency. In many occasions where the requirements are not high, the ordinary motor and the frequency converter are used to adjust the frequency. Inverter motor use.

4. Can the inverter single-phase 220v be transformed into a three-phase 380v?

Yes no. The inverter itself cannot be boosted, and it is impossible to change the three-phase 380v from the single-phase 220v. In theory, this is feasible. The transformer will be used to increase the single-phase 220V to 380V, and then the single-phase 380V to three-phase 380V.

5. The belt driven by the high-power motor has a reducer connected to the motor. What is the function of the reducer here?

The purpose of the reducer can be summarized briefly:

Reduce the speed and increase the output torque at the same time. The torque output ratio is multiplied by the motor output by the speed reducer, but be careful not to exceed the rated torque of the gearbox.

Deceleration also reduces the inertia of the load, and the reduction in inertia is the square of the reduction ratio. You can see that the general motor has an inertia data.

6. Answer the reason why the motor speed is slow when starting the motor?

If it is only slow at start, it will be normal after starting. It may be that the starting capacitor does not match, or the motor design is originally like this (according to the design of the place), or it may be that the starting time is too long due to factors such as excessive load resistance.

If the speed is slow after starting, the problem may be insufficient voltage, mismatched capacitance, and high rotational resistance.

7. How to choose the brush of the rotor of the wound type asynchronous motor rotor?

It is mainly determined according to whether the working condition of the brush satisfies the current density (A/cm2) and the linear velocity (m/s) of the circumferential edge of the collector ring. Determine the formula: 1 brush current capacity (A) = brush current density (A / cm2) × brush width L (cm) × brush thickness b (cm) ≥ motor rotor rated current (A); 2 collector ring The linear velocity (m/s) at the edge of the circumference = the rated motor speed (r/m) / 60 (s) × the circumference of the collector ring (m) ≤ the specified range (m / s) applicable to the brush.

The commonly used brushes are three types: non-ink brush, electrochemical graphite brush and metal graphite brush. During use, care should be taken to check the brush activity, brush pressure and wear level. The brush should be able to move up and down freely in the brush holder without jamming. When the card is brushed, smooth both sides of the brush on the abrasive cloth. The pressure of the brush should be adjusted according to the type and model of the brush. At present, the brush pressing spring attached to the brush holder is mostly a tension compression spring, and the pressure thereof gradually decreases with the wear of the brush, so the brush pressure should be adjusted at any time during the running of the motor.

8. Ask 60HZ motor to be used on 50HZ power supply, what should you pay attention to?

This is because the current frequency of the motor is lower than the design frequency, and the no-load counter electromotive force generated in the rotation is reduced, the no-load current is increased, and the motor is damaged, so that the no-load voltage is required to be lowered.

In the variable frequency speed control technology, the frequency of the motor and the stator voltage are simultaneously changed. That is, the frequency is reduced, the voltage is also reduced at the same time, and the motor will not over-current, and the ideal operation effect will be obtained.

9. Ask the inverter output terminal to add an output reactor, what is its role?

The output reactor is added at the output end of the inverter to increase the distance between the inverter and the motor. The output reactor can effectively suppress the instantaneous high voltage generated when the IGBT of the inverter is switched, and reduce the adverse effect of this voltage on the cable insulation and the motor.

The main function of the reactor is to limit the capacitive charging current of the motor connection cable and limit the voltage rise rate on the motor winding to 540V/μs. It is also used to passivate the inverter output voltage (switching frequency) steeply. Degree, reducing the disturbance and impact of power components (such as IGBT) in the inverter.

10. Can the AC servo motor be controlled by a frequency converter?

Because the inverter and servo are different in performance and function, the application is not the same, so it is not acceptable.

In the case of speed control and torque control, the general-purpose inverter is not very high, and the position feedback signal is added in the upper position to form a closed-loop frequency conversion for position control, and the accuracy and response are not high. Some existing frequency conversions also accept the pulse sequence signal to control the speed, but it seems that the position cannot be directly controlled.

In the case of strict position control requirements, only servo can be used, and the response speed of the servo is much larger than the frequency conversion. Some speed control and high response requirements also use servo control, which can be controlled by frequency conversion. The occasion can almost be replaced by a servo.

The key is two points: First, the price servo is much higher than the frequency conversion, and the second is the reason of the power: the maximum frequency conversion can be several hundred KW, or even higher, and the servo is up to several tens of KW. The basic concept of servo is accurate, accurate and fast positioning. Frequency conversion is a necessary internal link of servo control, and there is also frequency conversion in the servo drive (for stepless speed regulation).

11. Can the speed control motor start frequently?

The speed-regulating motor can be started frequently. The motors used for debugging by our company are all speed-regulating motors. It is often started frequently and there is no problem. However, it is best to minimize frequent starts. No matter how many times the motor starts frequently, it will damage the motor.

12. How do you know that the motor is a star/delta connection?

The star connection method is that one end of the three-phase winding is connected, and the other end is connected to a three-phase power supply, and the shape is like the letter "Y"; the triangle connection method is that the three-phase windings are connected end to end to form a "â–³" shape, and the top of the triangle is connected to the three-phase. power supply.

Their phase voltages are different. Generally, the rated voltage of the star-connected motor is 220V, and the rated voltage of the delta connection is 380V. The connection method is generally indicated on the inside and outside of the cover of the junction box, and different connections correspond to different power supply voltages.

13. What is the impact of the number of poles on the motor?

The motor currently has 2/4/6/8 motors and the number of motors for special applications may be higher. The more pole pairs of the motor, the lower the speed of the motor, but the greater the torque. When choosing a motor, you should consider how much the starting torque needs the load, such as when the load starts, it is no longer loaded. The starting torque needs to be large. If it is a high-power and large-load starting, it is also necessary to consider the step-down start (or the star-delta start). As for the problem of matching the speed of the load after determining the number of poles of the motor, you can consider different Diameter pulleys are used for transmission or with gears (gearboxes) for matching. If the power requirement of the load cannot be reached after passing the belt or gear transmission after determining the number of poles of the motor, then the power consumption of the motor should be considered.




----- Editor-in-Chief: Dalan Oil Pump Motor 02-Procurement Consultant

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