Using soft starter to build an intelligent motor control center

Once a time one of our customers ask to install three numbers of 150HP capacity soft starters (with auxiliary I/O's) to build an intelligent motor control center. Their main goal is to limit the high starting current of the chillers compressors. They do not need an expensive variable frequency drive (VFD) as the system is designed to operate at full capacity most of the times. They need a AC motor soft starter with Modbus RTU communications.
Soft starter
We recommend Gozuk made GS series soft starters, we have used their variable frequency drives (VFD) though. In China one hardly uses soft starters. It is either Star-Delta starting or straight VFDs. This is because there is no significant difference in price between a VFD and soft starter. Whilst both are way more expensive than the star-delta starter. In such application, we would use a soft starter made of Gozuk components that can communicate on Modbus! In the case of compressors, one common technique to reduce starting current is to keep the bleed-valve open that way the compressor's piston does not encounter load for the start-up period.

But nearly all major brands give you soft starters and VFDs. In China most popular is ABB. Some other Chinese brands also are emerging and people don't seem to be complaining. For an application, the first thing you've to look for is to see if you can get support for spares.

You can buy soft starters on, 100 hp soft starter, 200 hp soft starter...

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