The main step of inverter debugging - Sunland inverter

Investigation of the function of the inverter system

Before debugging the frequency converter, it is necessary to carefully read the operation instructions and related information of the inverter to be debugged to understand the application environment and precautions. Especially before the inverter is energized, it is necessary to carefully observe and check whether the inverter has obvious traces of failure, such as whether its input and output terminals meet the requirements of the manual. Pay special attention to whether there is new content added.

The main step of inverter debugging - Sunland inverter

The main step of inverter debugging - Sunland inverter

Inorganic no-load operation and debugging of the inverter

The following three steps are the most fundamental and important debugging operations for inorganic (i.e., not connected to the motor) and no-load (i.e., the motor without load) operation and debugging of the inverter:

(1) Ground the grounding terminal of the inverter and connect the power input terminal to the power supply through the leakage maintenance switch;

(2) Check whether the factory display of the inverter display window is normal, if it is incorrect, it should be reset, otherwise the supplier is required to return it;

(3) Understand the operation keys of the inverter.

The general inverter has 6 buttons, such as run, stop, prog, data/enter, up▲, and down▼, and the boundaries of the operation keys of different inverters are basically the same. In addition, some inverters also have function keys such as monitor/display, reset, jog, shift, etc., which need to be debugged.

The inverter is debugged with no-load operation

The following four steps are very important for the commissioning of the inverter with the machine (i.e., connected to the motor) and no-load (i.e., the motor without load).

(1) Set the power of the motor, the number of pole pairs, and determine the operating current of the inverter.

(2) Set the maximum output frequency and base frequency of the inverter and set the torque characteristics of the motor. The selection of the voltage/frequency (V/F) operation mode includes items such as the maximum operating frequency, the fundamental operating frequency (i.e., the base frequency), and the type of torque.

The highest frequency refers to the highest frequency that the inverter motor system can operate, because the maximum operating frequency of the inverter itself may be relatively high, when the maximum operating frequency of the motor is lower than the maximum operating frequency of the inverter, the frequency of the operation should be set according to the requirements of the motor and its load.

The basic operating frequency of the inverter refers to the dividing line between the constant power control and constant torque control of the motor by the inverter, which should be set according to the additional voltage of the motor. The torque type refers to whether the load is a constant torque load or a variable torque load.

In the process of device commissioning, the user can choose one operation mode according to the V/F operation mode diagram and load characteristics in the inverter application manual. The general inverter is equipped with a number of V/F curves for users to choose, and the appropriate V/F curve should be selected according to the load nature.

However, in the case of fan and pump loads, the torque operation code of the inverter should be set to the variable torque and reduced torque operation characteristics. In order to improve the low-speed performance of the inverter when starting, so that the output torque of the motor can meet the starting requirements of the production load, the starting torque should be adjusted. In the frequency conversion speed regulation system of three-phase asynchronous motor, the control of the rotation distance is more complicated. In the low frequency band, because the influence of resistance and leakage reactance cannot be ignored, if the v/f is still constant, the magnetic flux will be reduced, and the output torque of the motor will be reduced. Therefore, the voltage should be properly compensated in the low frequency range to increase the torque. Generally, the inverter is manually set and compensated by the user.

(3) Set the inverter to the operation form of the built-in keyboard, press the stop button and the run button, and observe whether the motor can stop and start normally.

(4) Set the function of the electronic thermal relay in the inverter according to the introduction in the inverter operation manual.

Since the threshold limit of an electronic thermal relay is the ratio of the additional current of the motor and the inverter, it is often used as a percentage. When the output current of the inverter exceeds its allowable current, the overcurrent maintenance facility will cut off the output of the inverter.

Therefore, the maximum threshold value of the inverter's electronic thermal relay cannot exceed the maximum allowable output current of the inverter. At the same time, it should be noted that the overload maintenance setting value of the inverter can also be modified.

The main step of inverter debugging - Sunland inverter

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