SJE-Rhombus Engineered Controls - VFD Pressure Controls

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5HP - 250HP Constant Pressure Applications

The VARIOspeed® Variable Frequency Drive features a user friendly HMI interface and is designed for constant pressure applications up to 250HP.

The VARIOspeed® HMI variable frequency drive (VFD) is designed for constant pressure control applications, including booster pumps, deep well submersible pumps and irrigation pumps.

As flow and head conditions change in the pumping system, the VARIOspeed® HMI VFD is able to automatically control the pump speed and maintain a constant discharge pressure. The desired set pressure is set on the VFD keypad. The pressure transducer measures the pump discharge pressure.  The VARIOspeed® HMI VFD is available from 5HP to 150HP @ 208-240V and 5HP to 250HP @380-480V, single phase or three phase supply voltage.  Built-in features include P.I.D. control, energy optimization control, adjustable electronic overload, automatic system restart, high and low pressure alarms, multiple pump control and more.

The parameters of the VARIOspeed® HMI VFD is pre-programmed in our factory to your specific application and is 100% factory tested to make installation quick and startup simple.  The standard VARIOspeed® HMI VFD is supplied in a NEMA 3R enclosure with a 0-200 PSI pressure transducer.  SJE-Rhombus® is a UL certified panel shop that can customized the VARIOspeed® HMI VFD to suit specific requirements, including duplex, triplex and quadplex VFD systems with automatic alternation and lead/lag operation.





  • (208 - 240V) 5HP - 150HP
  • (380 - 480V) 5HP - 250HP
  • Models available for single phase or three phase voltage supply
  • UL Listed for single phase and three phase voltage supply
  • Energy optimization control


  • PID control
  • Adjustable electronic overload
  • 0-200 PSI transducer (4-20 mA signal)
  • Adjustable Auto Start on pressure drop
  • Auto Stop on no-flow (sleep mode)
  • High and low pressure alarms
  • Automatic system restart
  • Programmable "Advanced Sleep" function
  • Pre-charge control (gradual pipe pressure)
  • 12 digital inputs (may be used for low water alarm)
  • 3 analog inputs
  • 2 relay outputs
  • 2 analog outputs
  • Modbus RTU communication (RS-485)
  • Mutiple pump control


  • Simple and user friendly display, keypad and Hand/Off/Auto switch

VARIOspeed® HMI Display Screens





For specifications on the VARIOspeed® HMI VFD, please contact the factory at 1-888-342-5753.


Available Downloads

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