What is IEC 61439?
IEC 61439 is a standard which is developed by International Electrotechnical Commission, Switzerland. To which equipment, it is applicable: it is applicable to Electrical panels and busways/busduct/bus trunking - Low-voltage…
World’s first Gas insulated line under a river successfully commissioned (GIL Construction and advantages)
We all know about overhead transmission lines and underground cable for power transmission at high voltage. ABB recently has successfully commissioned 1000 KV gas insulated transmission line(GIL) through a tunnel…
What is Trip circuit supervision relay(TCS,95)? Circuit diagram of TCS and working
You all know, how important a trip circuit is for a circuit breaker. if for instance, following problems will come in trip circuit, breaker will not trip when required or…
What is APFC (Automatic Power Factor Correction) relay/Power Factor controller and APFC Panel ? Working and wiring diagram
You all know, What we will do to improve system power factor ..install the capacitors. Consider below case: Suppose you have a electric system on which 10 nos LT motors(…
What is Unitised or Package or prefabricated or compact substation (CSS/USS) ? Single line diagram, area required and advantages?
Have you seen this (kindly see below picture) ? This is a outdoor 11000/440 volt substation on double pole structure. Why you need this ? Obviously you need Low voltage…
MCB(Miniature Circuit Breaker): Construction,Working (Operation),Use, Tripping Curves and Types
MCB(Miniature Circuit Breaker)Credit: ABB See above picture, have you seen this type of thing in your home ??? This is MCB .. in the above picture, four nos MCB are…
Buchholz relay(Gas actuated relay) in transformers-Construction, Working , Use, Diagram, specification, codes and standards , installation and testing
Buchholz relay in transformers -Construction, Working and Diagram: General : This relay was invented by Max Buchholz in 1931. it is used in those oil filled transformer having conservators. look…
What is cooling class of transformer i.e. AN, ONAN, ONAF and OFAF
As you all know, transformer contains windings which carry electric current and electric current in the transformer winding produce heat. This heat is taken up by oil in transformer tank…
Differences, advantages and disadvantages of Live tank and Dead tank SF6 circuit breaker
Before we go for comparing both types of Circuit breaker, just see pictures of both i.e. live tank and dead tank SF6 circuit breaker. How these breakers looks from outside.…
What is LM79, LM80 and LM70 testing on lights.
LM79, LM70, LM80 are test procedure developed and approved by illumnating Society of North America (IESNA) on LED lights. LM80 This test LM80 gives the age or lifetime of LED…
Terms related to Lighting and Lighting fixtures ..
Luminous flux of luminarie (Light fitting or bulb) Luminous flux is total light output emitted by luminarie. It is denoted by (?) or lumen or lm. Light emitted by a…
Potentiometer: Construction and Working
Potentiometer..when you hear the word ..what comes in your mind ..yes .. potential and meter ..means the meter that measures potential ..yes it is used to measure the potential as…
Bipolar Junction Transistor (BJT)
This is BJT , How it looks like Construction of BJT(Bipolar junction Transistor) Bipolar junction Transistor is a semiconductor device means it is made up of semiconductor materials i.e. silicon…
Field Effect Transistors (FET)
It has 3 terminal device just like BJT(bipolar junction transistor). It is also a semiconductor device. FET can be turned on and off by electric field. Two types of FET:…
Induction Wattmeter
Induction Wattmeter is used to measure power in AC Circuits. We all know Power = VI Cos(Theta) where V is the voltage , I is the Current and Theta is…
Electrodynamic or Dynamometer Instruments
This instrument is similar to PMMC(Permanent Magnet Moving Coil) Instruments except in place of permannet magnets , there is a coil . Construction: There is a coil which is divided…
Permanent Magnet Moving Coil (PMMC) Instruments
Construction & Working : simply in brief , there is a coil which is free to move and is surrounded by powerfull magnets. Now we dicuss in detail .. There…
Moving Iron instruments
As the name suggests , there is iron piece in these instruments ..the movement of this iron piece gives the necessary reading. These instruments are of two types i.e. attraction…
Current and ohm’s law
1. Drift velocity of electrons Electrons move in the conductor randomly when no voltage applied to it and so average velocity is zero. When a voltage applied to the conductor,…
Resistor Transistor Logic(RTL)
Now it is not used anywhere in the design of integrated circuits. In this type of ICs , only transistors and resistors are used. The RTL circuits basically performs the…
What is the use of silica gel/breather in transformer
Pic: A transparent box containing silica gel crystals You have seen this type of transparent box with blue crystals like substance inside. These blue crystals are silica gel. So what…
Difference between Live tank and dead tank current transformer
Before we start, lets go back to CT basics, what a CT does , obviously a 2000/1 amp delivers 1 amp at secondary when 2000 amp is flowing or 0.5…
Terms related to CT/PT(Burden, Accuracy Class, Instrument Safety factor, knee point voltage etc.)
There are many terms we come across when we read about current transformer(CT) and Potential transformer(PT) or voltage transformer(VT) /capacitive voltage transformer( CVT). below are meaning of these terms. CT/PT…
SF6 Gas circuit breaker: Construction, Working and Advantages
SF6 gas is an inert gas with dielectric strength and arc-extinguishing qualities. In SF6 breakers, the rate of rise of dielectric strength is very high and the time constant is…
What is CVT(Capacitive Voltage Transformer)
The capacitive-coupled potential transformer (CCPT) or Capacitive Voltage Transformer is a Voltage Transformer with a capacitive circuit as shown in the figure below. The two Capacitor C1 and C2 here…
Dissolved gas analysis (DGA) of Transformer Oil
When a oil immersed transformer is subjected to internal faults, than due to short circuit flowing through transformer windings, the temperature of windings rises, this give rise to rise in…
Capability curves of Synchronous Generator
Capability curves are a plot of apparent power capability (MVA), at rated voltage, using active power (MW) and reactive power (MVAR) as the two principle axis. Circumferences drawn with their…
Performance curves or operating characteristics of an Induction Motor
Performance curves means when motor performance is shown as a graph from starting of the motor to running. Generally variation of following parameters are noted at various loading of the…
Crawling and Cogging in induction motor
Both crawling and cogging effect is only observed in squirrel cage induction motor as in wound rotor inductor motor, this effect is not observed as toque is very large. Crawling:…
Pre-commissioning checks or testing on circuit breaker
Circuit breakers are installed indoor and outdoor. indoor in the panels , and outdoor in the panels or standalone. Circuit breaker can be air circuit breaker(ACB) or SF6 circuit breaker…