In เกจวัดแรง , working a motor past the base pole velocity is possible and provides system benefits if the design is carefully examined. compound gauge ราคา of a motor is a perform 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 within the U.S.). As illustrated, further poles cut back the bottom pole pace. If the incoming line frequency does not change, the speed of the induction motor might be lower than these values by a percent to slip. So, to function the motor above the base pole velocity, the frequency needs to be increased, which can be carried out with a variable frequency drive (VFD).
One purpose for overspeeding a motor on a pump is to use a slower rated speed motor with a lower horsepower score and function it above base frequency to get the required torque at a decrease current. This enables the number of a VFD with a decrease present ranking for use while still guaranteeing satisfactory management of the pump/motor over its desired working range. The decrease current requirement of the drive can reduce the capital cost of the system, depending on total system necessities.
The applications where the motor and the pushed pump function above their rated speeds can present extra flow and strain to the controlled system. This could end in a more compact system whereas rising its effectivity. While it may be possible to extend the motor’s pace to twice its nameplate velocity, it’s more frequent that the utmost velocity is extra restricted.
The key to these applications is to overlay the pump velocity torque curve and motor velocity torque to make sure the motor begins and capabilities throughout the entire operational speed range with out overheating, stalling or creating any important stresses on the pumping system.
Several factors also must be taken into account when considering such solutions:
Noise will increase with velocity.
Bearing life or greasing intervals may be decreased, or improved fit bearings may be required.
The greater velocity (and variable speed in general) will increase the danger of resonant vibration as a result of a important pace throughout the working vary.
The greater velocity will result in further power consumption. It is necessary to assume about if the pump and drive prepare is rated for the higher power.
Since the torque required by a rotodynamic pump increases in proportion to the square of pace, the other major concern is to ensure that the motor can present enough torque to drive the load on the elevated speed. When operated at a pace below the rated pace of the motor, the volts per hertz (V/Hz) can be maintained as the frequency applied to the motor is increased. Maintaining a constant V/Hz ratio retains torque manufacturing secure. While it will be best to increase the voltage to the motor as it’s run above its rated velocity, the voltage of the alternating current (AC) energy source limits the maximum voltage that is obtainable to the motor. Therefore, the voltage provided to the motor can’t continue to increase above the nameplate voltage as illustrated in Image 2. As proven in Image 3, the available torque decreases past 100 percent frequency as a result of the V/Hz ratio is not maintained. In an overspeed state of affairs, the load torque (pump) have to be under the obtainable torque.
Before operating any piece of equipment outside of its rated pace range, it is essential to contact the manufacturer of the tools to discover out if this can be accomplished safely and efficiently. For extra information on variable speed pumping, check with HI’s “Application Guideline for Variable Speed Pumping” at pumps.org.
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