1. What does the stall prevention function mean?
If the given acceleration time is too short, the output frequency of the inverter will change far beyond the change of the speed (electrical angle frequency). The inverter will trip due to the overcurrent and the operation will stop. This is called stalling. In order to prevent the stall from continuing to operate the motor, it is necessary to detect the magnitude of the current for frequency control. When the acceleration current is too large, the acceleration rate is appropriately slowed down. This is also true during deceleration. The combination of the two is a stall function.
2. What is the significance of the models that can be specified for the acceleration time and deceleration time, and the type of acceleration and deceleration time given together?
Acceleration and deceleration can be given for each type of machine, for short-time acceleration, slow deceleration occasions, or for small machine tools need to strictly specify the production of the tact time is appropriate, but for fan drive and other occasions, acceleration and deceleration time is longer, Acceleration time and deceleration time can be given together.
3. What is regenerative braking?
When the motor is running, if the command frequency is reduced, the motor becomes an asynchronous generator state operation and operates as a brake, which is called regenerative (electrical) braking.
4. Is it possible to obtain greater braking power?
The energy regenerated from the motor is stored in the filter capacitor of the inverter. Due to the relationship between the capacity of the capacitor and the withstand voltage, the regenerative braking force of the general inverter is about 10% to 20% of the rated torque. If using optional brake unit, it can reach 50%~100%.
5. Please explain the protection function of the inverter.
The protection functions can be divided into the following two categories: (1) Corrective actions are automatically performed after detection of abnormal conditions, such as overcurrent stall prevention and regenerative overvoltage stall prevention. (2) Block the power semiconductor device PWM control signal after detecting the abnormality, so that the motor will automatically stop. If over-current cuts off,
Regenerative over-voltage shutdown, semiconductor cooling fan overheating, and instantaneous power outage protection.
6. Why does the inverter's protection function act when the clutch is continuously loaded?
When the clutch is used to connect the load, the motor rapidly changes from the no-load state to the area where the slip rate is large at the moment of connection, and the large current that flows causes the inverter to trip overcurrent and cannot operate.
7. In the same factory, the large-scale motor moves together and the inverter stops during operation. Why?
When the motor starts, the starting current corresponding to the capacity will flow. The transformer on the stator side of the motor will generate a voltage drop. When the motor capacity is large, the pressure drop will also have a large effect. The inverter connected to the same transformer will make undervoltage or instantaneous stop. As a result of the judgment, the protection function (IPE) may occasionally act to stop the operation.
8, what is the frequency resolution? has no meaning?
For digitally controlled inverters, even if the frequency command is an analog signal, the output frequency is given a step. The smallest unit of this differential is called the frequency resolution. The resolution of the frequency conversion is usually 0.015~0.5Hz. For example, if the resolution is 0.5Hz, then the upper limit of 23Hz can be changed to 23.5.
24.0 Hz, so the action of the motor is also followed step-by-step. This causes problems for the use of a continuous coil control. under these circumstances,
If the resolution is about 0.015 Hz, one step for a 4-stage motor is 1 r/min or less, and sufficient adaptation is also possible. In addition, some models have different resolutions and output resolutions.
9. Is there any limit to the mounting direction when installing the inverter?
The structure of the inside and the back of the inverter considers the cooling effect, and the up and down relationship is also important for ventilation. Therefore, for the haplotype inside the disk,
Hang on the wall to take the vertical position, as far as possible vertical installation.
10. Is it possible to use a soft start without putting the motor directly into a fixed frequency inverter?
It is possible to operate at very low frequencies, but if the given frequency is high then the conditions for direct start with the commercial frequency power supply are similar. A large starting current (6 to 7 times the rated current) will flow, and the motor cannot be started because the inverter cuts off the overcurrent.
11. What should be taken care of when the motor exceeds 60Hz?
Pay attention to the following matters when operating above 60Hz
(1) Machines and devices must be fully operational at this speed (mechanical strength, noise, vibration, etc.).
(2) The motor enters the constant power output range, and its output torque must be able to maintain the work (shaft, pump, etc. shaft output power in proportion to the cube speed increase, so a little increase in speed should also pay attention to). (3) Bearing life issues should be fully considered.
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