There is a frequency converter, the operation panel can be controlled normally, and the adjustment frequency can also be changed from 0 to 50HZ. With an external potentiometer, the frequency can not be adjusted to 20HZ. What is the reason?
The panel adjustment frequency can be, the external given does not work, indicating that the inverter itself is no problem, it is necessary to check whether the external potentiometer of the inverter gives you a problem with the surrounding components or lines.
First ensure that the potentiometer is good, and then ensure that the wiring to the inverter terminal is correct, the rest is the frequency converter frequency setting problem.
First, the choice of the resistance of the potentiometer should correspond to the requirements on the manual.
The selection of the resistance value of the external potentiometer of the inverter, the analog signal given by the inverter is generally: 0~10V, 4~20ma, so when selecting the potentiometer setting value, the following two situations should be considered:
1, voltage signal 0~10V
When the external power supply voltage is 10V, if the potentiometer of 10K resistance value is selected, the working current is 1mA. According to the field, as long as the analog signal is less than 1mA, the anti-interference ability can be used. Therefore, the resistance of the potentiometer should be less than or equal to 10K.
If the output voltage of the inverter is 0-10V, the potentiometer of 10K should be selected. If the output voltage of the inverter is 0-5V, the potentiometer of 4.7K should be selected. If the current is too large, it will cause endless power loss. .
2, the current signal 4~20ma
When the external input signal is 4~20ma, a 500 ohm resistor is connected in series in the circuit. Under the 10V power supply, the resistance of 20ma corresponds to 500.
To check if the potentiometer pins are wired correctly, when measuring the potentiometer, measure whether the potentiometer pin voltage changes.
The fixed terminals on both sides of the potentiometer are directly connected to the 10V power supply and ground signal on the inverter terminal, and the sliding adjustable terminal in the middle of the potentiometer is connected to the analog output signal of the inverter, and then adjust the resistance of the potentiometer to see the output. Does the voltage change?