VFD technology was developed in response to the limitations of AC power. AC motors, such as the ones powering industrial pumps, rotate at a rate set by the incoming power and the number of poles inside the motor. Since AC power in the US is supplied at a standard 60 Hz frequency, this means that standard single-phase two-pole motors spin 60 times per second.
Adding more sets of poles reduces the speed without any need to alter the incoming electrical frequency. However, you can’t just swap out an electric motor with more or fewer poles every time you need to change the operating speed of a pump. Transistor systems that allow you to turn specific motor poles on and off have been available for decades, but these systems are complex and often lack the fine control needed for industrial pumping. VFD equipment changes the frequency of the power supply instead, allowing for exact and immediate adjustments to pump operation.
The VFD works by taking in AC power at the 60 Hz frequency, converts it into direct current (DC) power through a rectifier circuit, and sends it through a DC bus to filter the voltage further. Then, power reaches the inverter which creates pulses of DC energy that function like AC current. The pulsing nature of the output mimics AC power enough to create the correct induction processes needed to spin the rotor of the motor. Since DC is easier to control in voltage and frequency, using it instead of true AC power allows the VFD to adjust the electrical supply on the fly. A series of transistors, especially the Insulated Gate, Bipolar Transistor (IGBT), give manual or automatic control over the power output and the resulting EDDY pump performance. Power is easily increased to a sludge pump under heavy load and then dropped again after a blockage passes or the texture of the slurry or sludge being pumped changes.
Benefits of Utilizing a VFD When Using a Slurry Pump
- Reduce pump maintenance by keeping the equipment running at its maximum efficiency point and reducing total system pressure.
- Control energy costs, which is an essential factor in many waste or manufacturing industries with limited margins.
- Eliminates or reduces the number of control valves that all require individual sensor installation and maintenance and often aren’t appropriate for slurry or sludge processing.
- Gain control over motor speed without switching to costly DC motors.
VFDs allow slurry pumps and their motors to adjust on the fly to changes in the material being pumped, preventing damage and ensuring the system is always running at maximum energy efficiency. Gaining variable speed control without costly programmable logic controllers is especially helpful during dewatering processes that require very slow processing speeds.
By utilizing the EDDY Smart Pump Technology, the VFD can be controlled on the fly using on-board smart chips and computers, requiring little to no input from pump operators, thus keeping the pump running optimally with maximum uptime and more profits.