From Pumpsolutions
Normally Pumps are controlled with throttling valves or dampening vanes. This is basically an inefficient method which is similiar to driving a car with the accelerator pressed to the floor while controlling your speed with the brake. A VFD on the other hand allow precise control of the motor output, with significant reductions in the power required to handle the load. As an example, a VFD running load at 80% speed requires about 50% of the horsepower or energy required to run it at 100%. When these savings are applied over the annual hours of operation, significant savings can be achieved. With this and the motor protection that is standard with the VFD's there is no reason not to consider using one on your next upgrade or system install.
Concerned about start up and programming? No need - call and if possible we can arrange a technician to assist and train in the features of this device.
PLEASE CHECK OUT our new WEG ON-LINE Catalog. We now offer much more to assist you in your system requirements or upgrades. Pricing shown is list, call or inquire about you discount. Can't find something give us a call and we will assist you.
==SUPER NEW JUST IN==
MULTI-Pump System Control for up to 4 Pumps with 1 VFD Controller
Check out the brochure and give us a call for further details. Start saving energy and controlling and monitoring your system the way it should be.
NEW - For Applications requiring greater than a 20:1 constant torque speed range using the WEG VFD Controller coupled with a WEG W21 Motor
Call for Details today
NEW Optimal Flux - When combining a WEG drive with a WEG motor the design characteristics are loaded into the drive. The control algoritham increases motor flux slightly at low speeds, thereby allowing the same torque to be developed at lower current. The result is optimal motor flux at low speeds to produce full torque while minimizing motor losses.
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PRICES SUBJECT TO CHANGE PLEASE CONTACT US FOR LATEST PRICING
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Add $327.00 for 4-20Ma Pressure Drive Signal or Add $195.00 for 4-20Ma Temperature Drive Signal
A variable-frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. A variable frequency drive is a specific type of adjustable-speed drive. Variable-frequency drives are also known as adjustable-frequency drives (AFD), variable-speed drives (VSD), AC drives, microdrives or inverter drives. Since the voltage is varied along with frequency, these are sometimes also called VVVF (variable voltage variable frequency) drives.
VFD Operation
When a VFD starts a motor, it initially applies a low frequency and voltage to the motor. The starting frequency is typically 2 Hz or less. Starting at such a low frequency avoids the high inrush current that occurs when a motor is started by simply applying the utility (mains) voltage by turning on a switch. When a VFD starts, the applied frequency and voltage are increased at a controlled rate or ramped up to accelerate the load without drawing excessive current. This starting method typically allows a motor to develop 150% of its rated torque while drawing only 50% of its rated current. When a motor is simply switched on at full voltage, it initially draws at least 300% of its rated current while producing less than 50% of its rated torque. As the load accelerates, the available torque usually drops a little and then rises to a peak while the current remains very high until the motor approaches full speed. A VFD can be adjusted to produce a steady 150% starting torque from standstill right up to full speed while drawing only 50% current.
With a VFD, the stopping sequence is just the opposite as the starting sequence. The frequency and voltage applied to the motor are ramped down at a controlled rate. When the frequency approaches zero, the motor is shut off. A small amount of braking torque is available to help decelerate the load a little faster than it would stop if the motor were simply switched off and allowed to coast. Additional braking torque can be obtained by adding a braking circuit to dissipate the braking energy or return it to the power source.