Constant Pressure Water Supply Project: VFD Specification Checklist

A constant-pressure project VFD specification should define the motor, supply, hydraulic target, pressure feedback, operating sequence and protection requirements. Specifying only pump power and a pressure setpoint is not enough to produce a reliable quotation or commissioning plan.

The VFD cannot correct an undersized pump, unsuitable pipework or an incorrectly located sensor. Hydraulic design and drive selection must be checked together.

What Information Is Required?

• Motor nameplate: rated voltage, current, power, frequency, speed and motor type.
• Site supply: voltage, phase, frequency, tolerance and available short-circuit protection.
• Pump data: quantity, duty/standby arrangement, design flow, head and operating range.
• Pressure control: target pressure, transmitter range, signal type and sensor location.
• Control sequence: local/remote/automatic modes, sleep, wake, alternation and fault response.
• Installation: enclosure location, ambient temperature, altitude, cable length and communications.

Selection Example

Consider a three-pump booster set with two duty pumps and one standby pump. Each motor is 7.5 kW, 380 V, and its nameplate current is supplied. The project requires constant discharge pressure, automatic lead-pump rotation and continued operation after one pump faults.

The quotation should identify one drive per controlled motor, the pressure-feedback arrangement, coordination logic and required external protection. The final VFD size must be confirmed against motor current and site conditions rather than the 7.5 kW label alone. The control narrative should also state which device becomes responsible for pressure control after a fault.

Common Mistakes

• Quoting from motor kW without checking rated current.
• Omitting the pressure-transmitter range and signal type.
• Using a pressure setpoint without confirming the pump curve and safe system pressure.
• Leaving sleep, wake and pump-fault behavior undefined.
• Ignoring enclosure cooling, altitude or long motor cables.

AUSENIST Solution

AUSENIST can review the motor schedule, pump arrangement and control narrative, then propose an appropriate YS620 or YS820 configuration for engineering confirmation. Support can include basic parameter planning, pressure-feedback requirements, multi-pump logic review and a repeatable project quotation scope.

Selection should not be finalized when hydraulic duty, motor data or the required operating sequence is missing. Special environments, communication interfaces and local approvals must be confirmed for the exact project. For tender preparation, also see what drawings and I/O information should accompany a pump VFD RFQ.

Send us the motor nameplate, quantity, voltage, application and project requirements. We can prepare VFD selection and quotation.