Seeking solutions regarding inverter interference issues
Thread Content
Our company’s cold mixing machine is equipped with two frequency converters and a Siemens 200 PLC. The touch screen communicates with the PLC via an Ethernet cable, while the frequency converters communicate through a 485 interface. When the emergency stop button is pressed, the frequency converters sometimes stop working and other times they don’t. The emergency stop function cuts off the PLC’s output power, resulting in the shutdown of all outputs. The frequency converters are controlled only via the 485 interface; thus, the cold mixing process can be stopped, but the 45 KW hot mixing process cannot be stopped as it operates at 132 KW. Is it due to excessive interference? We have been trying to solve this problem for many days without success. Could it be a programming issue?
General control systems use direct wiring, and communication through such methods is unreliable. It is recommended to use Siemens Profibus cables for communication; it is best to run them in tubes to achieve shielding effects.
This is a complete set of equipment that was purchased. I like frequency converters that are unfamiliar to me – what else can I do? The manufacturer won’t come and handle it, and I’ve done everything I can; it just doesn’t work
The emergency stop signal can be connected using a hard wire. In this way, at the very least, there will be no problems when the machine stops
It is still recommended to use hard contacts for interlocking signals; communication itself involves digital signals, so it should be less susceptible to interference. However, communication can be unreliable and prone to disconnections. If you can’t make the changes yourselves, you can also ask the manufacturer to make corrections; this is clearly a design flaw that affects usability.