In เกจ์วัดแรงดัน , operating a motor beyond the bottom pole pace is possible and offers system benefits if the design is rigorously examined. The pole velocity of a motor is a function of the number poles and the incoming line frequency. Image 1 presents the synchronous pole velocity for 2-pole by way of 12-pole motors at 50 hertz (Hz [common in Europe]) and 60 Hz (common in the U.S.). As illustrated, additional poles 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 base pole pace, the frequency must be increased, which can be accomplished with a variable frequency drive (VFD).
One reason for overspeeding a motor on a pump is to use a slower rated velocity motor with a lower horsepower score and function it above base frequency to get the required torque at a lower current. This enables the selection of a VFD with a decrease current rating to be used while still making certain satisfactory control of the pump/motor over its desired operating vary. เกจวัดแรงดันแก๊ส of the drive can scale back the capital value of the system, depending on general system necessities.
The functions the place the motor and the driven pump function above their rated speeds can provide additional flow and pressure to the controlled system. This may lead to a more compact system whereas rising its efficiency. While it might be potential to extend the motor’s speed to twice its nameplate velocity, it is more widespread that the maximum velocity is extra restricted.
The key to those functions is to overlay the pump speed torque curve and motor velocity torque to make sure the motor starts and capabilities throughout the entire operational speed range without overheating, stalling or creating any important stresses on the pumping system.
Several factors also need to be taken under consideration when contemplating such solutions:
Noise will enhance with speed.
Bearing life or greasing intervals could additionally be decreased, or improved fit bearings could also be required.
The larger velocity (and variable pace in general) will increase the danger of resonant vibration because of a critical speed within the operating range.
The higher speed will result in extra energy consumption. It is necessary to consider if the pump and drive prepare is rated for the upper power.
Since the torque required by a rotodynamic pump will increase in proportion to the sq. of velocity, the opposite major concern is to ensure that the motor can provide sufficient torque to drive the load on the increased velocity. When operated at a pace below the rated velocity of the motor, the volts per hertz (V/Hz) could be maintained because the frequency applied to the motor is elevated. Maintaining a constant V/Hz ratio retains torque manufacturing secure. While it might be perfect to increase the voltage to the motor as it’s run above its rated pace, the voltage of the alternating current (AC) power supply limits the utmost voltage that’s out there to the motor. Therefore, the voltage equipped to the motor cannot continue to extend above the nameplate voltage as illustrated in Image 2. As proven in Image 3, the obtainable torque decreases beyond one hundred pc frequency as a result of the V/Hz ratio is not maintained. In an overspeed scenario, the load torque (pump) should be below the available torque.
Before working any piece of apparatus outdoors of its rated speed vary, it’s important to contact the manufacturer of the equipment to determine if this can be accomplished safely and effectively. For more data on variable velocity pumping, refer to HI’s “Application Guideline for Variable Speed Pumping” at pumps.org.
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