A programmable logic controller (PLC) based power factor correction method for a 3-phase Induction Motor (IM) through switching of shunt capacitors is proposed in this paper. A 3 phase IM has a low power factor (pi) a...
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ISBN:
(纸本)9781467385886
A programmable logic controller (PLC) based power factor correction method for a 3-phase Induction Motor (IM) through switching of shunt capacitors is proposed in this paper. A 3 phase IM has a low power factor (pi) at no load as it draws large magnetizing current and the active power delivered to the motor is low, which is utilized to overcome the no-load losses. The PLC based power factor improvement algorithm is developed and implemented on a 3 Phase laboratory prototype IM coupled to a DC generator and the effectiveness of the algorithm is tested under no-load and loaded condition. Based on the instantaneously measured value of power factor, the PLC switches the appropriate bank of capacitors into the circuit depending on the load condition to improve the pf. Large scale use of PLC in industrial automation, adaptability, simple implementation and economics justified its selection as the switching controller. A significant improvement in power factor under different loading conditions is observed.
Eight 500 MHz cavities are applied in the storage ring of the Shanghai Synchrotron Radiation Factility (SSRF). In order to tune the cavities for different changing parameters and operation modes, the control system is...
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Eight 500 MHz cavities are applied in the storage ring of the Shanghai Synchrotron Radiation Factility (SSRF). In order to tune the cavities for different changing parameters and operation modes, the control system is essential for operations. The tuning is achieved by synchronizing the drive signal and the cavity probe signal. The error signal defined as their subtraction is amplified and used to drive a stepping motor, which in turn moves a metallic plunger in or out of the cavity by programmable logic controller (PLC). The tune speed is set to be 1 kHz/s.
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