Although the auxiliary control mode of the frequency converter has many advantages, if the control circuit wiring is unreasonable, it will often bring adverse effects to the normal operation of the frequency converter, and even cause unnecessary faults. Today, based on my experience, I summarized six taboos about the wiring of inverter control circuit:

1. The wires laid in the control circuit of the frequency converter shall be separated from the main circuit cable (power line), so as to avoid the harmonic interference components in the main circuit of the frequency converter polluting the control circuit of the frequency converter;

2. Because the fault signal of the frequency converter and the output signal of the multi-function contact and other terminals may drive the high-voltage AC contactor / relay, the wiring should be separated from the terminals or contacts of other control circuits to prevent the fault point from being hit by the high voltage.

3. In order to prevent misoperation caused by interference signal, shielded wire or twisted pair with strong anti-interference ability should be selected when wiring the low-power control circuit of the frequency converter (such as the wire used by the sensor under the PID control function);

4. For the length of the wire of the frequency converter control circuit, 50m is usually used as the reference point (in some cases, the value is 100m, which is mainly related to the cross-section of the wire used, the strength of the material signal and other factors). When the wiring distance exceeds this length, relay circuits or relays should be used to amplify the signal;

5. When crimping the control circuit wire of the frequency converter, pay special attention to the accessibility of the analog signal to prevent damage to the auxiliary control electronic circuit of the frequency converter caused by the reversal of accessibility;

6. When the frequency converter is powered on, the digital multimeter with buzzer function gear (the output voltage of this gear is higher than that of other gears) cannot be used to measure the on / off of the control circuit. To prevent the electric quantity in the digital multimeter from being transmitted by the probe to the control terminal of the frequency converter, causing malfunction!