The primary function of DVR is to minimize the voltage sags on lines that cater to sensitive equipment. The control voltage applied to the load by injecting a voltage of compensating amplitude, frequency and phase angle to the distribution line. The voltage turns to the desired magnitude in case of any disturbances. The device functions as a filter between the transmission line and the facility, thus enabling the facility to continuously receive clean power. The DVR primarily responsible for restoring the quality of voltage delivered to the end user when the voltage from the source is not appropriate to be used for sensitive loads.
Filter: Capacitive filter is used in this project. It removes the ripples from the output of rectifier and smoothens the D.C. Output received from this filter is constant until the mains voltage and load is maintained constant. However, if either of the two is varied, D.C. voltage received at this point changes. Therefore a regulator is applied at the output stage. Voltage regulator: As the name itself implies, it regulates the input applied to it.
Valve trays are trays that has holes which are covered by caps that are lifted up by the vapour flowing into the holes. This provides excellent contact between liquid and vapour. A decrease in vapour flowrate will cause the cap height to decrease as shown
Therefore it is necessary to change the values of capacity C and inductance L accordingly. It can be made using feedback from current value changes, which change inversely with a load value. Currently, in order to support the constant voltage level with variable load resistance, the so called “Tap-changing-under-load (TCUL) transformers” are used. But this transformer also does not solve completely the problem of the load resistance change with the attempt to keep the necessary phases. In single wire case, one must increase L and decrease C proportionally to decreasing current (as it shown on Fig.5.4) The values of capacitors and inductors can be selected in accordance with the value of voltage change steps in transformer.
This means the passband of the filter have a smooth and monotonically decreasing frequency response. Another advantage of this type of filter is selecting a higher order filter will then have a steeper attenuation slope near the cut-off frequency each time the order of the filter is increased. However, the disadvantage of increasing the order of the filter is to add more components to the circuit. Another disadvantage of having a Butterworth filter is the roll-off between the passband and stopband have a slow response. There is also ringing and overshoot in the step response.
By adding a capacitor beside a rectifier circuit, it reduces AC component which raise the average output voltage and supply current when the output voltage decreases as figure 1.2 Shown below. Figure 1.2: diode bridge rectifier (electronicstutorials,2016) 1.4. Voltage regulator Voltage regulator is a system used to insure a steady voltage after rectifier it in linear power supply circuit. The resistance of the regulator changes in accordance with the load due to a constant output voltage. The voltage regulator chip is made to function like a variable resistor, constantly modifying a voltage divider to preserve a constant output voltage, and continually receding the difference between the input and the output voltages as waste heat.
The design of a heat exchanger requires a balanced approach between the thermal design and pressure drop . Shell and tube heat exchanger design is normally based on correlations, among these; the Kern method and Bell-Delaware method are the most commonly used correlations. Kern method is mostly used for the preliminary design and provides conservative results. Whereas, the Bell-Delaware method is more accurate method and can provide detailed results. It can predict and estimate pressure drop and heat transfer coefficient with better accuracy.
The use of non-linear amplifiers, e.g. class C, etc. means that transmitter efficiency levels will be higher - linear amplifiers are naturally feeble. 1.3.3 Dis-Advantages of Frequency Modulation: One of the small dis-advantages of frequency modulation is that the demodulator is a little more fancy, and hence lightly more expensive than the very simple diode detectors used for AM. Also requiring a tuned circuit adds cost.
Why we need transformer in power system? We need transformers in power system because of several reasons one most important reason is that electricity is generated at low voltages and in receiving end we also need low voltages but due to the high cost of transmitting low voltages and high currents we use step up transformers to step up the low voltage into high voltages and low currents which will also reduced the I2R losses during transmission of electricity and at receiving side this high voltage is step down to low voltage by using step down transformer. 6.1.2. Why calculation of transformer sizing is necessary in power system? Transformer sizing is necessary so that the selected transformer is capable of supplying the power needed by the load, able to bear the short circuit current and the inrush current without being damaged.