In Which Applications Can a Pump Motor Be Operated Above Base Speed?

In some instances, operating a motor past the base pole speed is feasible and offers system benefits if the design is fastidiously examined. The pole velocity of a motor is a operate of the quantity poles and the incoming line frequency. Image 1 presents the synchronous pole speed for 2-pole through 12-pole motors at 50 hertz (Hz [common in Europe]) and 60 Hz (common in the U.S.). As illustrated, pressure gauge 4 นิ้ว ราคา cut back the base pole velocity. If the incoming line frequency does not change, the velocity of the induction motor shall be lower than these values by a % to slip. So, to function the motor above the bottom pole velocity, the frequency must be elevated, which may be accomplished with a variable frequency drive (VFD).
One cause for overspeeding a motor on a pump is to make use of a slower rated speed motor with a decrease horsepower score and function it above base frequency to get the required torque at a decrease current. This allows the choice of a VFD with a decrease present ranking for use while nonetheless guaranteeing passable management of the pump/motor over its desired working range. The decrease present requirement of the drive can reduce the capital value of the system, depending on total system requirements.
The applications where the motor and the driven pump operate above their rated speeds can provide extra circulate and stress to the controlled system. This could result in a extra compact system while increasing its effectivity. While it might be possible to extend the motor’s pace to twice its nameplate velocity, it is more widespread that the maximum speed is extra restricted.
The key to these purposes is to overlay the pump velocity torque curve and motor speed torque to make sure the motor starts and functions all through the entire operational speed range with out overheating, stalling or creating any significant stresses on the pumping system.
Several points also must be taken into account when considering such options:
Noise will improve with pace.
Bearing life or greasing intervals may be lowered, or improved fit bearings may be required.
The greater velocity (and variable velocity in general) will enhance the risk of resonant vibration because of a crucial velocity within the working vary.
The greater pace will lead to further energy consumption. It is essential to consider if the pump and drive train is rated for the upper energy.
Since the torque required by a rotodynamic pump will increase in proportion to the square of pace, the opposite main concern is to ensure that the motor can present sufficient torque to drive the load on the elevated speed. When operated at a velocity below the rated speed of the motor, the volts per hertz (V/Hz) could be maintained as the frequency applied to the motor is elevated. Maintaining a constant V/Hz ratio retains torque production secure. While it might be ideal to extend the voltage to the motor as it’s run above its rated velocity, the voltage of the alternating current (AC) power source limits the utmost voltage that is out there to the motor. Therefore, the voltage equipped to the motor cannot proceed to increase above the nameplate voltage as illustrated in Image 2. As shown in Image three, the obtainable torque decreases beyond 100% frequency as a result of the V/Hz ratio isn’t maintained. In an overspeed situation, the load torque (pump) must be under the available torque.
Before operating any piece of kit outside of its rated velocity vary, it’s important to contact the producer of the equipment to find out if this can be done safely and efficiently. For extra info on variable pace pumping, check with HI’s “Application Guideline for Variable Speed Pumping” at

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