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How can harmonic content upstream of a motor drive be contrasted to warrant good energy saving during motor running? |
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A DC inductance, connected to the speed control DC-Bus, standard-supplied on 18.5 to 630kW ratings of the VFPS1 version, or an IND series three-phase inductance, externally installed for 0.75 to 15kW ratings, and connected upstream, reduce current consumption at input to a maximum value equal to 110% output current. The reason for this being the current harmonic distortion of input current is radically reduced, as illustrated in blue on the two following curves. 
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Can the starting of a motor and the adjustment of its speed be made from to different places, Local and Remote? |
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In Local mode, motor starting and stopping are controlled by the RUN-STOP
buttons, on the drive front, while speed adjustment, by the potentiometer on-board. This is valid for the VFS11 and VFNC1 versions or by an external potentiometer, connected to one of the available 0…10V or 4…20mA analog inputs on types VFS11, with two of them, and VFP7, with three. By enabling the Remote mode, via selector switch, connected to one of the digital inputs of the motor drive, duly programmed by simple parameter change, start and stop control can be obtained using external push buttons, selector switches or signals. An example is a signal coming from a PLC. Instead, the speed adjustment is enabled at one of the analog inputs, connected to an external signal, either as 0…10V or 4…20mA. |
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How can the pressure be possibly maintained constant in a hydraulic system? |
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This
type of operation can be obtained by using a variable frequency
drive, such as our VF, and a pressure transducer which supplies the
drive with an analog signal directly proportional to the pressure
level of the monitored system. After having programmed, with the remote keypad, the pressure level which one requires to maintain and enabled the PID algorithm of the drive, the PID will begin to modulate the motor speed until the pressure value is stabilsed at the required level. It is important to take into account the subsequent energy saving with this sort of supervision. The motor does not constantly operate at its rated speed, as would happen with direct-on-line starting, but only consumes the energy required to maintain the programmed pressure value. |
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