Q: What is SVC?
A: SVC is static variable compensation using thyristors to control a reactor or shunt capacitive bank.
Q: Which microcontroller is used in this project?
A: A 40 pin microcontroller from 8051 family is used in this project.
Q: Which inductive load is used in this project?
A: A 40 W tube light choke is used in this project.
Q: Can I replace choke by induction motor?
A: Yes, the choke can be replaced by induction motor.
Q: Why is the 100W bulb used?
A: A 100 W bulb is used to demonstrate as Linear or resistive load
Q: Why is the lamp used in series with the inductor?
A: A lamp is used in series with the inductor, because a standard 40 watt tube light choke cannot be directly connected to mains.
Q: Why are 2.5µF capacitors used?
A: The 2.5µF capacitors are used to compensate for the lagging power factor.
Q: Why lamp is used in series with the choke?
A: We use an inductor and a lamp. Inductor is for the lagging current and lamp is for the linear load. As the type of inductor used is nothing but a tube light choke, it is not possible to use the same across the mains supply of 230 volts directly. Hence the same lamp comes in series with the choke during inductor operation. However in linear load selection, the inductor is bypassed by the switch provided .Thus while the inductor is bypassed and only, lamp remains in the circuit. As regards to other wattage of lamps to be used variation of lagging current is possible so the different pf. More the wattage of the lamp, more becomes the lagging current. But never exceed more than 200 watts of lamp as it may result in burning of the choke.
Q: What is the formula for calculating smoothing capacitor value?
A: There is some approximated formula .Peak to peak ripple voltage = Load current in amps / (2*line frequency in hertz *capacitance in farads). But as rule of thumb for 1 A current 1000uF is best. Thus it is load dependent.
Q: Why are two transformers being used?
A: One transformer is used as PT while the other is as CT. Hence 2 numbers are must. This is an academic project which is designed to understand the technology used and not designed for real time use. The load capacity is about 200 watts.
Q: Can we watch the waveforms of current lagging behind the voltage?
A: For watching 2 channels on CRO/DSO one needs common ground point. The common ground point is available for ZVS and ZCS pulses as they are at the DC side ,thus they can be seen. But for ac waveform watching if we take the CT output ac to one channel we cannot connect the PT (12 volt from the transformer) to the other channel as there would be no common ground reference possible. The only way is to use 2 more step -down transformers and connect one as PT (230 volt to 12 volt)by connecting the same to 230 volt side to mains and the secondary of the same transformer ,one point can go to the common point of the CRO/DSO while the other can be used for the 1st channel. The 2nd transformer is used as a CT and the low voltage side is connected across the 2nd 10-Ohm/10 watt resistor. The 230 volt side is connected to a 4.7 k resistor. Then one point goes to common point of DSO/CRO and the other to the 2nd channel of the DSO/CRO. All these are to be carried out at your place.
Q: What is FACTS?
A: FACTS or flexible AC transmission system involves use of power electronic devices to ensure smooth transmission of AC power by compensating the reactive power.
Q: What is TSC?
A: TSC stands for ThyristorSwitched Capacitor, used for switching appropriate number of shunt capacitors in lines to improve power factor
Q: Can a bulb of lower wattage be used?
A: Yes, a bulb of lower power rating can be used.
Q: Is the capacitor special for power factor correction or can I use any capacitor with the same rating?
A: Please note this is a project for understanding the technology and is not meant for commercial use. So we have used easily available capacitors in the market. They are fan capacitors. However one can use any type for the project as long as the capacitance and voltage rating are met. But the real PF correction capacitors are different.
Q: How did you calculate the value of capacitor connected parallel with the load?
A: The value of capacitor coming into the circuit is decided by the program. We had taken some arbitrary value of 2.2uF (C) by trial, apparently adequate enough to compensate the PF developed by the simple inductor used. The total capacitance value goes on increasing by C or C+C or C+C+C or C+C+C+C as the inductive current goes on increasing. One can increase the inductive current by changing the wattage of the lamp which is used in series with the inductor. For example a 15 watt lamp will produce too little a lagging current while a 100 watt can result in much higher inductive current.