Goodrive300-21 integrated machine for air compressor
Common EMC problems and solution
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Appendix D Common EMC problems and solution
D.1 Interference problems of meter switch and sensors
Interference phenomenon
Pressure, temperature, displacement, and other signals of a sensor are collected and displayed by a
human-machine interaction device. The values are incorrectly displayed as follows after the inverter
is started:
The upper or lower limit is wrongly displayed, for example, 999 or -999.
The displayed value changes randomly (often occurred to pressure transmitter).
The display of values is stable, but there is a large deviation, for example, the temperature is
dozens of degrees higher than the common temperature (usually occurring on thermocouples).
A signal collected by a sensor is not displayed but functions as a drive system running
feedback signal. For example, the inverter is expected to decelerate when the upper pressure
limit of the compressor is reached, but in actual running, it starts to decelerate before the upper
pressure limit is reached.
After the inverter is started, the display of all kinds of meters (such as frequency meter and
current meter) that are connected to the analog output (AO) terminal of the inverter is severely
affected, displaying the values incorrectly.
Proximity switches are used in the system. After the inverter is started, the indicator of a
proximity switch flickers, and the output level flips.
Solution
Check and ensure that the feedback cable of the sensor is 20 cm or farther away from the
motor cable.
Check and ensure that the ground wire of the motor is connected to the PE terminal of the
inverter (if the ground wire of the motor has been connected to the ground block, you need to
use a multimeter to measure and ensure that the resistance between the ground block and PE
terminal is lower than 1.5 Ω).
If a large number of meters or sensors are disturbed, it is recommended that you configure an
external C2 filter on the inverter input power end.
D.2 Interference on RS485 communication
The interference described in this section on RS485 communication mainly includes communication
delay, out of synchronization, occasional power-off, or complete power-off that occurs after the
inverter is started.
If the communication cannot be implemented properly, regardless of whether the inverter is running,
