第六章单元测试
- Frequency converter is a kind of device which transforms the fixed frequency (usually frequency frequency of 50 Hz) alternating current (three-phase or single-phase) into three-phase AC power supply with continuously adjustable frequency (mostly 0-400 Hz).（ ）
- The general frequency converter usually uses the AC-DC-AC mode to convert the power frequency alternating current into three-phase AC with adjustable frequency and voltage, that is, the power frequency alternating current at the power grid side is first rectified into direct current, and then the direct current is converted into the alternating current with controllable frequency and voltage.（ ）
- The starting process of the drive system with variable frequency speed regulation starts from very low frequency (at this time, the synchronous speed is also very low) and low output voltage. The speed of frequency rise can be set arbitrarily, so that the starting current can be effectively limited to a certain range, and the problem of mechanical shock during starting can be completely solved. This starting characteristic is very superior.（ ）
- The control circuit of frequency converter generally includes input circuit, output circuit and auxiliary interface, etc. The input circuit receives the command signal (switching value or analog signal) of the controller (PLC), and the output circuit outputs the status information of the frequency converter (switching or analog output in normal condition, abnormal output, etc.), and the auxiliary interface includes communication interface, external keyboard interface, etc.（ ）
- If the user encounters problems in the parameter debugging process and wants to start debugging again, the operation method of parameter clearing or initialization can be used. In the parameter setting mode, use the M knob to select the parameter No. as Pr.CL (parameter clear) and ALLC (parameter clear), set their values to 1 to return the parameters to their original values.（ ）
- RM terminal represents________ in the terminal distribution diagram of Mitsubishi Inverter with model FR-740.（ ）
- STF terminal represents______in the terminal distribution diagram of Mitsubishi Inverter with model FR-740.（ ）
- in the terminal distribution diagram of Mitsubishi Inverter with model FR-740, the STR terminal represents________.（ ）
- in the parameter setting of Mitsubishi frequency converter with model FR-740, the parameter Pr.79 is set as __________.（ ）
- In the parameter setting of Mitsubishi frequency converter with model fr-740, the parameter pr.2 is set as ______________.（ ）
A:对 B:错
答案:对
A:对 B:错
A:对 B:错
A:对 B:错
A:对 B:错
A:Low speed control terminal B:Forward control terminal C:High speed control terminal D:Medium speed control terminal
A:High speed control terminal B:Reverse control terminal C:Medium speed control terminal D:Forward control terminal
A:Low speed control terminal B:Reverse control terminal C:High speed control terminal D:Forward control terminal
A:Operation mode B:Upper limit frequency C:Lower limit frequency D:Reference frequency
A:Upper limit frequency B:Acceleration time C:Lower limit frequency D:Deceleration time
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