Principle of Tan Delta TestA pure insulator when is connected across line and earth, it behaves as a capacitor. In an ideal insulator, as the insulating material which acts as dielectric too, is 100 % pure, the electric current passing through the insulator, only have capacitive component. There is no resistive component of the current, flowing from line to earth through insulator as in ideal insulating material, there is zero percent impurity.In a pure capacitor, the capacitive electric current

Polarization Index Test (PI Value Test) along with Insulation Resistance Test (IR Value Test) is conducted on HV electrical machine to determine service condition of the insulation. IP test is conducted especially to determine the dryness and cleanliness of the insulation.In insulation resistance test, a high DC voltage is applied across the insulator. This applied voltage is then divided by current through the electrical insulator to obtain resistive value of the insulator. Since, as per Ohm’s

What is a Transducer?An electrical transducer is a device which is capable of converting physical quanties into a proportional electrical quantity such as voltage or electric current. Hence it converts any quantity to be measured into a usable electrical signal. This physical quantity which is to be measured can be pressure, level, temperature, displacement etc. The output which is obtained from the transducer is in the electrical form and is equivalent to the measured quantity. For example, a t

A potentiometer is an instrument which measures unknown voltage by balancing it with a known voltage. The known source may be DC or AC. The working phenomenon of DC potentiometer and AC potentiometer is same. But there is one major difference between their measurements, DC potentiometer only measures the magnitude of the unknown voltage. Whereas an AC potentiometer measures both the magnitude and phase of unknown voltage by comparing it with a known reference. There are two types of AC potentiom

What is a Potentiometer?Apotentiometer(also known as apotorpotmeter) is defined as a 3 terminalvariable resistorin which theresistanceis manually varied to control the flow ofelectric current. A potentiometer acts as an adjustablevoltage divider.How Does a Potentiometer Work?A potentiometer is a passive electronic component. Potentiometers work by varying the position of a sliding contact across a uniform resistance. In a potentiometer, the entire input voltage is applied across the whole length

Various methods are used for measurement of three phase power in three phase circuits on the basis of number of wattmeters used. We have three methods to discuss: Three wattmeters method Two wattmeters method Single wattmeter method.Let us discuss one by one each method in detail.Measurement of Three Phase Power by Three Wattmeters MethodThe circuit diagram is shown below-Here, it is applied to three phase four wire systems, current coil of all the three wattmeters marked as 1, 2 and 3 are conne

Before we study the internal construction of electrodynamometer type wattmeter, it is essential to know the working principle of electrodynamometer type wattmeter. Dynamometer type wattmeter works on very simple principle and this principle can be stated as when any current carrying conductor is placed inside a magnetic field, it experiences a mechanical force and due to this mechanical force deflection of conductor takes place.Construction and Working Principle of Electrodynamometer Type Wattme

What is a Low Power Factor Wattmeter?A low power factor meter is an instrument that is used to accurately measure low values of power factor. Before we study more about the low power factor meter, we need to understand why we need a low power factor wattmeter in the first place (as opposed to a standard electrodynamometer wattmeter)The answer is simple: a standard wattmeter gives inaccurate results.Now there are two main situations where we should not use an ordinary wattmeter in measuring a low

Digital frequency meter is a general purpose instrument that displays the frequency of a periodic electrical signal to an accuracy of three decimal places. It counts the number events occurring within the oscillations during a given interval of time. As the preset period gets completed, the value in the counter display on the screen and the counter reset to zero. Various types of instruments are available which operates at a fixed or variable frequency. But if we operate any frequency meter at d

Digital Multimeter is a device which has two words in its name: Digital and Multimeter. Let’s first try to analyze why do we have them there i.e. what do each of them actually convey which in turn helps us understand what does a multimeter do. The first word – digital – indicates that the meter has a digital or liquid crystal display while the next word – multimeter – indicates that this single device can be used for multipurpose i.e. to measure more than one parameter. A typical digital multime