In some cases, working a motor past the bottom pole speed is feasible and provides system benefits if the design is fastidiously examined. The pole pace of a motor is a perform of the number poles and the incoming line frequency. Image 1 presents the synchronous pole pace 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, ราคาเกจวัดแรงดันน้ำ cut back the base pole velocity. If the incoming line frequency doesn’t change, the speed of the induction motor will be lower than these values by a percent to slip. So, to operate the motor above the base pole pace, the frequency needs to be elevated, which may be done 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 lower horsepower rating and function it above base frequency to get the required torque at a lower current. This permits the selection of a VFD with a decrease present score for use while still guaranteeing passable control of the pump/motor over its desired operating vary. The lower current requirement of the drive can scale back the capital price of the system, relying on total system requirements.
The applications the place the motor and the driven pump operate above their rated speeds can provide further circulate and stress to the controlled system. This could end in a extra compact system whereas rising its effectivity. While it may be attainable to increase the motor’s speed to twice its nameplate speed, it is more frequent that the maximum velocity is extra limited.
The key to those purposes is to overlay the pump speed torque curve and motor speed torque to make sure the motor starts and functions all through the entire operational velocity vary without overheating, stalling or creating any important stresses on the pumping system.
Several factors also must be taken into account when contemplating such solutions:
Noise will improve with speed.
Bearing เกจวัดแรงดัน4บาร์ or greasing intervals could also be decreased, or improved match bearings may be required.
The larger velocity (and variable pace in general) will improve the chance of resonant vibration because of a important velocity throughout the working range.
The higher velocity will end in further energy consumption. It is important to consider if the pump and drive practice is rated for the upper power.
Since the torque required by a rotodynamic pump will increase in proportion to the sq. of pace, the opposite main concern is to make sure that the motor can provide enough torque to drive the load at the increased velocity. When operated at a speed under the rated velocity of the motor, the volts per hertz (V/Hz) can be maintained because the frequency utilized to the motor is increased. Maintaining a continuing V/Hz ratio keeps torque production secure. While it might be best to extend the voltage to the motor as it is run above its rated velocity, the voltage of the alternating current (AC) power source limits the maximum voltage that is 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 out there torque decreases beyond one hundred pc frequency because the V/Hz ratio is not maintained. In an overspeed state of affairs, the load torque (pump) should be beneath the obtainable torque.
Before working any piece of kit outdoors of its rated speed vary, it’s essential to contact the manufacturer of the gear to determine if this can be carried out safely and effectively. For extra info on variable velocity pumping, check with HI’s “Application Guideline for Variable Speed Pumping” at pumps.org.
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