Nov 24, 2020
What should I do if the inverter is still running after the motor is damaged?
The motor is burned and the inverter is still running. Why? ★Although the inverter has soft start, soft stop, stepless speed regulation and special requirements of increase and decrease characteristics, it has protection functions such as overload, overvoltage, undervoltage, short circuit, grounding, and various early warning, forecast information and status information. And diagnosis function; but if the inverter and the motor power matching are not selected correctly, or the most basic parameter selection is not set correctly, the motor burns, but the inverter still has output; this situation generally does not occur when you are familiar with the inverter Of the masters at work.
Simply put, correctly setting the parameters of the inverter and the motor, such as: rated power, rated frequency, rated voltage, rated current, rated output capacity, etc. are the prerequisites to ensure the normal operation of the inverter and give full play to the performance of the inverter and motor. And mastering the operation method of basic parameter setting is the key link to operate the inverter.
Regardless of the brand of inverter and motor, if the selected power matches are consistent, the motor parameters must be self-learned (also commonly known as automatic tuning). It is an accurate copy of the parameters on the motor nameplate that drag the inverter to the ground. To the internal memory chip of the inverter; copying the motor parameters into the inverter includes two steps: parameter upload and parameter download. The parameter upload refers to uploading the parameters in the inverter control board to the memory (EEPROM) of the operation display board. Save; parameter download refers to download the parameters stored in the operation display panel to the control panel of the inverter and save them.
In this way, once the motor has a problem, the detection sensor inside the inverter will be analyzed by the processor to make a judgment. When a certain standard is reached, the inverter will immediately execute and stop the U, V, W output voltage of the inverter, and the motor will be protected.
★The rated parameters of the inverter. (1) Rated parameters on the inlet side. ①Rated voltage → The rated voltage of the low-voltage inverter is single-phase 220~240V (mainly small-capacity inverters in household appliances), three-phase 220V or 380~460V. The rated voltage of low-voltage inverters in my country is mostly three-phase 380V, and the rated voltages of medium and high-voltage inverters are 3kV, 6kV and 10kV.
②Rated frequency→Generally, the power frequency is 50Hz or 60Hz, and it is 50Hz in my country. (2) Rated parameters on the output side. ①Rated output voltage → Since the output voltage of the inverter changes with frequency, its rated output voltage can only be specified as the maximum value of the output voltage, usually it is always equal to the rated voltage on the input side.
②Rated output current→rated output current refers to the maximum current allowed to be output for a long time, which is the main basis for users to choose the inverter. ③Rated output capacity → rated output capacity is determined by the product of rated output voltage and rated output current:. Se=√3UeIex10?3. In the formula, S……rated output, kVA; Ue……rated output voltage, V; Ic……rated output current, A. It should be pointed out: The rated capacity of the inverter is expressed by the rated output current (A), by the rated active power (kw), and by the rated apparent power (kVA).
④ Equipped motor capacity → The equipped motor capacity specified in the inverter manual refers to the maximum motor capacity that can be equipped with a continuous and constant load. When the rated capacity of the inverter is expressed by the rated apparent power, the required apparent power calculated by the motor should be less than the apparent power that the inverter can provide. The specific size can be determined by referring to the above requirements. When using the frequency converter, the apparent power of the motor is calculated as follows:
S=P?/η.cosφ in the formula S-……motor apparent power, kVA; P?……motor rated power, kW; cosφ……motor power factor, this value is due to the influence of higher harmonics. The power factor under the frequency voltage is smaller, which can be corrected according to the performance of various inverters;
η...The efficiency of the motor, as mentioned above, is also smaller than the value under the power frequency voltage. ⑤Overload capacity → The overload capacity of the inverter refers to the ability to allow its output current to exceed the rated current, which is generally specified as 150%le, Imin or 120%le, Imin.
⑥ Output frequency range → the maximum adjustment range of the output frequency, usually expressed by the maximum output frequency fmax and the minimum output frequency fmin. The frequency range of various inverters is not the same, usually the maximum output frequency is 200~500Hz, and the minimum output frequency is 0.1~1Hz.
⑦Starting torque at 0.5Hz→This is an important characteristic index of the inverter; a good inverter can output a high starting torque of 180%~200% at 0.5Hz. This kind of frequency converter can realize short-term smooth acceleration and deceleration according to load requirements, and quickly respond to sudden changes in load.