Free Expert Guides on Power Systems, Circuit Design & Electrical Troubleshooting

Before we introduce Kelvin Bridge, it is very essential to know what is the need of this bridge, though we have Wheatstone bridge which is capable of measuring electrical resistance accurately (usually an accuracy of around 0.1%).To understand the need of Kelvin bridge we must first recognize 3 important ways to categorize electrical resistance: High Resistance:Resistance that is greater than 0.1 Mega-ohm. Medium Resistance:Resistance that ranges from 1 ohm to 0.1 Mega-ohm. Low Resistance:Under

Wheatstone BridgeFor measuring accurately any electrical resistance Wheatstone bridge is widely used. There are two known resistors, one variable resistor and one unknown resistor connected in bridge form as shown below. By adjusting the variable resistor the current through the Galvanometer is made zero. When the current through the galvanometer becomes zero, the ratio of two known resistors is exactly equal to the ratio of adjusted value of variable resistance and the value of unknown resistan

Blavier’s Test is used to find the earth fault location in an underground cable. The two ends faulty cable are mentioned as sending end and far end respectively as shown in fig 1. In this test, the sending end of the cable must be open and isolated and the resistance between sending end and earth point is measured by keeping the far end isolated from earth and then it measured keeping far end of the faulty cable, shorted to the ground.Suppose, we get, resistance values R1 and R2 in these two sai

This bridge provide us the most suitable method for comparing the two values of capacitor if we neglect dielectric losses in the bridge circuit. The circuit of De Sauty’s bridge is shown below.Battery is applied between terminals marked as 1 and 4. The arm 1-2 consists of capacitor c1 (whose value is unknown) which carries current i1 as shown, arm 2-4 consists of pure resistor (here pure resistor means we assuming it non inductive in nature), arm 3-4 also consists of pure resistor and arm 4-1 co

Before we introduce this bridge let us know more about the uses of mutual inductor in bridge circuits. Now one question must arise in our mind that why we are so much interested in mutual inductance, answer to this question is very simple we will use this mutual inductor in Heaviside bridge circuit. We use standard mutual inductor in finding out the the value of unknown mutual inductor in various circuits. Mutual inductor is used in various circuits as main component in determining the value of

Hay’s bridge is a type of AC bridge circuit that is used to measure the self-inductance of a coil with a high-quality factor (Q > 10). It is a modified version of Maxwell’s bridge, which is suitable for measuring coils with a medium quality factor (1 < Q < 10). In this article, we will explain the construction, theory, phasor diagram, advantages, and disadvantages of Hay’s bridge.What is Self-Inductance?Self-inductance is defined as the property of a coil or circuit that causes it to op

Voltage controlled oscillator (VCO), from the name itself it is clear that the output instantaneous frequency of the oscillator is controlled by the input voltage. It is a kind of oscillator which can produce output signal frequency over a large range (few Hertz-hundreds of Giga Hertz) depending on the input DC voltage given to it.Frequency Control in Voltage Controlled OscillatorMany forms of VCOs are generally used. It can be of RC oscillator or multi vibrator type or LC or crystal oscillator

Crystal oscillators operate on the principle of inverse piezoelectric effect in which an alternating voltage applied across the crystal surfaces causes it to vibrate at its natural frequency. It is these vibrations which eventually get converted into oscillations.These oscillators are usually made of Quartz crystal, eventhough other substances like Rochelle salt and Tourmaline exhibit the piezoelectric effect because, quartz is inexpensive, naturally-available and mechanically-strong when compar

What is a Gunn Diode Ocillator?A Gunn Diode Oscillator (also known as a Gunn oscillators or transferred electron device oscillator) are a cheap source of microwave power and comprise of Gunn diode or transferred electron device (TED) as their major component. They perform a similiar funciton as Reflex Klystron Oscillators. In Gunn oscillators, the Gunn diode will be placed in a resonant cavity. A Gunn oscillator is comprised of two major components: (i) A DC bias and (ii) A tuning circuit.How a

What is a Wien Bridge Oscillator?A Wien-Bridge Oscillator is a type of phase-shift oscillator which is based upon a Wien-Bridge network (Figure 1a) comprising of four arms connected in a bridge fashion. Here two arms are purely resistive while the other two arms are a combination of resistors and capacitors.In particular, one arm has resistor and capacitor connected in series (R1 and C1) while the other has them in parallel (R2 and C2).This indicates that these two arms of the network behave ide