Is it possible to use one variable speed drive to run multiple motors at one time?

Yes. A single Variable Speed Drive (VSD) can operate multiple motors simultaneously, provided that all motors are intended to run at the same speed and frequency. Since the drive supplies a common output frequency, independent speed control of individual motors is not possible.

Conditions

The following conditions must be met when using one drive to control multiple motors:

• All motors must start and run at the same time.
• All motors will operate at the same output frequency commanded by the drive.
• The combined motor load must not exceed the drive's rated capacity.
• The application must not require individual motor speed regulation.
• Each motor will need to have its own motor thermal protection device.

Drive Sizing and Configuration

When selecting and programming the drive:

• Set the Nominal Motor Current parameter to the sum of the Full Load Amps (FLA) of all connected motors.
• Set the Rated Motor Power parameter to the total horsepower (HP) or kilowatt (kW) rating of all connected motors.
• Verify that the sum of all motor currents does not exceed the drive's rated output current.
• Verify that the total motor power does not exceed the drive's rated power.

Protection Requirements

The drive's internal motor overload protection is designed for a single motor and does not adequately protect multiple motors connected in parallel.

Therefore:

• Each motor must have its own overload and/or over-temperature protection device.
• Individual motor protection must comply  with Article 430, Part C of the National Electrical Code, and any applicable local electrical
  codes.
• An overload event on one motor must either:
  • Command the drive to stop, or
  • Disconnect the affected motor from the drive output