The technical parameters of the inverter (Variable-frequency Drive, VFD) are divided into the input side and the output side. The technical parameters of the input side of the VFD include input voltage, number of phases and frequency; The technical parameters of the output side include additional output voltage, additional current, additional capacity, capacity, frequency accuracy, frequency resolution, protection level and other performance indicators.
1. Additional data on the input side
(1) Input voltage U (IN). That is, the additional operating voltage on the power supply side. In China, the input voltage of low-voltage VFD is generally 380V (three-phase) and 220V (single-phase). In addition, the VFD also specifies the promised fluctuation scale of the input voltage, such as 10%, -15% - +10%, etc.
(2) Number of phases: single-phase and three-phase.
(3) Frequency f (inch). That is, the power frequency (often called the power frequency), which is 50Hz in China. The frequency of the promised shake is generally 5%.
2. Extra data on the output side
(1) Additional output voltage U(N). The U(N) boundary is said to be the maximum output voltage, since the output voltage of the VFD changes with frequency. It is determined by the additional operating voltage, which is generally equal to the input voltage U (IN).
(2) Additional current I(N). The maximum current that the VFD promises to output over a long period of time.
(3) Additional capacity S(N). Determined by the product of the additional line voltage U(N) and the additional line current I(N), S(N) = 1.732×U(N)×I(N).
(4) Capacity P(N). The maximum promised motor capacity under continuous constant load.
Note: In the production machinery, the capacity of the motor is mainly determined according to the heating situation. Under variable load, intermittent load and short-term load, as long as the temperature rise does not exceed the promised value, the motor is promised to be overloaded for a short time (a few minutes or dozens of minutes), while the VFD does not agree. Therefore, when choosing a VFD, the working conditions of the load should be fully considered.
(5) Overload ability. Refers to the multiple and moment when the output current of the inverter promises to exceed the additional value, as determined by the inverter module. The overload of most VFDs can be specified at 150% and 1min; 180%, 5s. It can be seen that the promised overload time of VFD is insignificant compared with the motor.
In addition, there are performance indicators such as frequency accuracy, frequency resolution, and protection level.
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