In factories, inverters are key for controlling motors, helping them run at the right speed and save energy. Sometimes, several motors need to run at exactly the same speed, or work together to move one big thing, like a long production line. Using one bigger inverter to control multiple motors at once can be a cheaper and smarter way to do this. How you start the motors decides which method you use: starting them all together, or starting them one after another.

Method 1: Starting and Stopping Together

• When to Use It: When motors (especially identical ones, made by the same factory) must run at the same speed, perfectly in sync.

• How It Works: One large inverter powers all the motors simultaneously. They start and stop together.

• The Big Plus: It saves money and gets the job done well.

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• Picking the Right Inverter:

  • The inverter must be big enough to handle all motors combined.

  • The inverter must be strong enough (provide enough electrical current) for all the motors. Its rated current needs to be at least 1.2 times the total current all the motors use.

• Important Things to Remember:

  • Control Mode: You must use open-loop V/F control. Other smarter controls need details about one specific motor and won't work well here.

  • Matching Motors: The motors shouldn't be too different in size. It's best if they are the same model, made by the same company, even the same batch. This helps them run together smoothly.

  • Watch the Wires: Keep all the wires running from the inverter to the motors as short as possible. Long wires cause problems. If the total wire length is too long, you might need extra parts (like an output reactor or filter) near the inverter.

  • Protect Each Motor: Every single motor needs its own thermal overload protector (like a heat-sensing switch) right before it. This protects it if it gets too hot.

  • Stopping Fast: If the motors need to stop very quickly, you'll likely need a special braking unit and resistor. Some smaller inverters have the braking unit built in—just add the resistor.

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Method 2: Starting One After Another

• When to Use It: When different parts of a machine need to start at different times.

• How It Works: The inverter acts like a power source. You switch its power to one motor at a time.

• The Big Plus: You need fewer inverters, saving cost.

• The Critical Rule: Never, ever let two or more motors run from the inverter at the same time. If this happens, the inverter will be overloaded and likely damaged.

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In Summary

Using one inverter for multiple motors (starting together or separately) is a smart, money-saving trick in factories. To make it work safely and well, you must pick an inverter that's powerful enough and follow the specific rules for how you start the motors (like using the right control mode, matching the motors, keeping wires short, adding individual motor protection, and preventing overlap). Doing this right means reliable equipment and lower costs.