The low-voltage frequency converter cannot adjust speed at low frequencies
Thread Content
The unit uses a Schneider ATV61 1.75kw low-voltage frequency converter, and there is an issue where the motor speed cannot be adjusted below 30HZ at low frequencies. The problem persists even after replacing the frequency converter; I seek advice from experts.
Don’t know what speed control method is being used? It is a potentiometer used to adjust the speed; for a 4-20mA current signal, check whether there is any change in current at the speed control terminal, or use a signal generator. Check whether the terminals are connected correctly, and ensure that the frequency range of the set parameters matches that of the signal.
What type of load is it? Is the low-frequency torque sufficient?
We found a filter at the output of the inverter; by removing that filter, the motor was able to start at low frequency normally. The distance from the motor to the cabinet is about 700 meters – could this be too far, resulting in severe signal attenuation? We also checked the filter and found it to be in good condition. Thank you all for your help.
The load is a reciprocating pump; the issue has now been resolved – normal operation was restored after removing the filter located next to the inverter output.
I’m not sure what structure this filter has; if an inductor is placed first and a capacitor later, then that’s the correct configuration, as it results in a PW waveform. Generally, there should be no capacitor after the inverter. Go to the site to see that the structure of the filter is independent of power.
Why is another filter needed for the output? It should generally be a reactor, I don’t understand what this means; I’m still learning about it
Are there inverters and motors with a frequency setting of 1.75? Check the minimum frequency parameter
What is the purpose of installing filters on the output? 1. Prevent high-frequency harmonics from damaging the motor insulation? A 700-meter cable – it will filter out any high frequencies, right? 2. Sell more products by using the gimmick of harmonics?