What is VFD pump control?
Variable frequency drives are used for adjusting flow or pressure to the actual demand. They control the frequency of the electrical power supplied to pumps or fans. Significant power savings can be achieved when using a VFD pump. The pump adjusts its revolutions to a given setpoint via a regulating loop.
How does a PLC control a VFD?
The VFD can be controlled remotely by using PLC/DCS systems. The PLC has to give set point for VFD drive to control the motor speed, this can achieved either automatically from the PLC or by the operator action from the HMI.
Can VFD control pressure?
The VFD regulates water pressure as demand fluctuates, and the input power required by the pumping system is minimized. Simply put, the VFD will monitor the pressure and draw just enough power to ensure that the system maintains demand.
How do you select a VFD for a pump?
The most important consideration when choosing a Variable Frequency Drive (VFD) is to know the type of load that is being applied to the motor because it will determine the size and cost of the VFD. The VFD must have sufficient current capability so that the motor can produce the required torque for the load.
How do you control pump pressure?
Therefore, to control the flow of a centrifugal pump, simply set the output pressure to the point on the P-V diagram that allows the pump to deliver the desired flow rate. The output pressure of the pump is set using a back pressure regulator. Once the pressure is set, the flow rate to the process is established.
How ladder logic controls VFD with PLC?
How to Control VFD with PLC using Ladder Logic
- Prepare a Control and Power drawing.
- Commissioning and Parameters Programming in VFD.
- Prepare a PLC program.
- Prepare a SCADA design.
How frequency is controlled in VFD?
VFDs manipulate the frequency of their output by rectifying an incoming AC current into DC, and then using voltage pulse-width modulation to recreate an AC current and voltage output waveform.
Do you need a pressure tank with a VFD?
When all the taps are closed, a pressure tank will help prevent the pressure from spiking, while a VFD ramps the pump down. As long as the flow needed is more than the minimum required for that particular system, the pump will continue to run.
How does a VFD affect a pump curve?
A VFD can help here by raising the pump’s operating speed to a higher-than-standard rpm so the pump curve and system curve intersect at the desired flow rate — but at the expense of higher power requirements. Evaluating pump performance requires a BEP versus speed curve for the maximum diameter impeller.
How does a VFD work in a lag system?
A single VFD can be used in a basic lead-lag system to regulate pressure by directly controlling the lead pump motor’s speed, while turning the lag booster pumps on and off through each pump’s across-the-line starter (See Figure 1). This scheme uses the VFD’s discrete outputs (dry output relays) to control each booster pump’s motor contactor.
What is a variable voltage direct drive (VFD)?
VFDs control the speed of AC induction motors by controlling the frequency and voltage supplied to the motor. While mechanical devices can be installed at a pump’s output to adjust flow, a VFD regulates flow by adjusting the motor/pump speed. This approach is much better for a number of reasons: Uses a minimum amount of energy
Can a VFD control a motor/pump?
VFDs have been used to control pumps for many years. However, advanced pump-specific VFDs now allow users to improve motor/pump control and protection without the need for inefficient mechanical devices or costly PLCs. Christopher Jaszczolt is an application engineer with the Drives and Motion Division of Yaskawa America, Inc., in Waukegan, Ill.
How does the controllogix PAC work with the Siemens VFD?
The ControlLogix PAC will be controlling a pump with a simple ON/OFF command and its velocity by setting a speed set-point to the VFD. In response, the Siemens VFD will return the actual speed reference and VFD status information controlling the pump. This exchange of control data and status information is all performed by the HMS gateway.