Notebook

How to open a circuit breaker

Bibi Mohanan February 20, 2016

Once inside your box you should turn off the breaker being changed,There will be a black wire coming off the breaker - you need to loosen the screw and remove this wire. The wire goes to the circuit branch in your house that is controlled by the breaker. Set this wire end aside - it is not live but don't let it contact anything less you accidentally make it live!

The breaker is plugged in to a rail in the bottom of the breaker box, the rail is live. You have to release breaker which has a detent that locks it to the rail by tilting and removing the breaker.

You then need to put the replacement breaker - must be the exact same rating or you risk burning down your house! - Make sure its off, then tilt it in and snap-lock it in place. Now replace the black wire to the circuit branch and turn the breaker on.

If you want to be extra safe, turn off the master breaker at the top before you change anything, then turn it back on after you've changed the breaker.

remember there will be some exposed electrical contacts when you do this. You'd better be able to recognize and avoid them.

How to open a circuit breaker

Reviewed by Bibi Mohanan on February 20, 2016 Rating: 5

Types of circuit breaker

Bibi Mohanan February 20, 2016

According different criteria there are different types of circuit breaker. According to their arc quenching media the circuit breaker can be divided as-

Oil circuit breaker.

Oil circuit breaker

Air circuit breaker.

3. SF₆ circuit breaker.

4. Vacuum circuit breaker.

According to their services the circuit breaker can be divided as-

Outdoor circuit breaker
Indoor breaker.

According to the operating mechanism of circuit breaker they can be divided as-

Spring operated circuit breaker.
Pneumatic circuit breaker.
Hydrolic circuit breaker.

According to the voltage level of installation types of circuit breaker are referred as-

High voltage circuit breaker.

Medium voltage circuit breaker.
Low voltage circuit breaker.

Types of circuit breaker

Reviewed by Bibi Mohanan on February 20, 2016 Rating: 5

Difference between Fuse and Circuit breaker

Bibi Mohanan February 20, 2016

Electrical Fuse

Circuit breaker

• The fuse is a device working on the electrical and thermal properties of the conducting material, while a circuit breaker is a device working on the electromechanical principles.

• Once used a fuse has to be replaced but the circuit breaker can be reused after correction of the fault in the system.

• Fuses offer protection against only power overloads, while circuit breaker offers protection against power overloads and short circuits (voltage imbalances)

Difference between Fuse and Circuit breaker

Reviewed by Bibi Mohanan on February 20, 2016 Rating: 5

Difference between Isolator and Circuit breaker

Bibi Mohanan February 20, 2016

Here I am telling about the difference between isolation switch as compared to a circuit breaker.
An isolating switch is a switching device that may not be able to break a normal load current or a short circuit current. Usually an isolation switch is used on the supply side of a circuit breaker to provide visual proof that the circuit is broken and there is no possibility of power flowing through.
A circuit breaker is a switching device that not only can interrupt normal current flowing through an electrical load, but can also protect the circuit by interrupting a fault current created by a short circuit.

Circuit breaker with parts

Circuit breaker

Isolator switch

Rotory isolator switch

In household power and other lower power circuit breakers, there are sensing mechanisms within the circuit breakers to sense electrical currents above expected levels. This internal sensing mechanism will "trip" the circuit breaker, interrupting the current and therefore protecting the circuit much like a fuse will do.

The circuit breaker can be reset and energise the circuit again after the short circuit or fault is removed.

However, it should be noted that most circuit breaker manufacturers only test their molded case circuit breaker (the ones you use in your house) once for their short circuit rating. This means theoretically that the circuit breaker may not be able to interrupt another short circuit if it had to interrupt one that is close to its maximum rating.

In higher voltages, safety concerns dictate that an isolator switch be used on the supply side of a circuit breaker so that workers can see and lock the isolator switch in the open position after using the circuit breaker to de-energise the circuit.

Difference between Isolator and Circuit breaker

Reviewed by Bibi Mohanan on February 20, 2016 Rating: 5

Physical significance of power factor

Bibi Mohanan February 20, 2016

What is power factor?
Power factor = cosine of the angle between voltage and current= cosθ . This is the instant answer from all. The other definitions are , cosθ= ratio of active power to apparent power or it is the ratio of Resistance to the impedance in the circuit.

These all are definitions and expressions that we all know. But, actually what is the physical significance of power factor? What does it actually mean?

" Power factor is the measure of effectiveness of utilization of available power."

The power in an ac circuit is mainly of three types.Apparent power, Active power and Reactive power.
Apparent power is the total power supplied to the circuit . It is given by,

S= VI Volt Ampere
But actually the circuit does not utilizes the applied power completely (if it is not a purely resistive circuit). The part of the applied power which is actually consumed by the circuit is called active power and it is given by,

P= VI cosθ watts

The rest of the applied power is circulating in the circuit with out doing any actual work. It s called reactive power and is given by,
Q= VI sinθ Volt Ampere Reactive (VAR)

Thus, the power factor is the measure of percentage of the power consumed .

i.e, " Power factor is the measure of effectiveness of utilization of available power."

The power factor can be also measured in terms of percentage.

In a purely resistive circuit, the power factor is 1, or 100%. This means that, in a pure resistive circuit, the applied power is completely utilized by the circuit. (Reactive power is zero)

If in a circuit, the power factor is 0.5, or 50 % it means that only 50% of the applied power is utilized by the circuit.

Physical significance of power factor

Reviewed by Bibi Mohanan on February 20, 2016 Rating: 5

Electrical power cable

Bibi Mohanan February 19, 2016

Power cables are mainly used for power transmission & distribution purpose. It is an assembly of one or more individually insulated electrical conductors, usually held together with an overall sheath. Electrical power cables may be installed as permanent wiring within buildings, buried in the ground and run overhead or exposed. Flexible power cables are used for portable devices, mobile tools and machinery.

Construction of Power Cable

There are various parts of a cable to be taken care of during construction. The power cable mainly consists of

CONDUCTOR 

INSULATION 

LAY for Multicore cables only

BEDDING 

BRAIDING/ARMOURING (IF REQUIRED)

OUTER SHEATH

CONDUCTOR
 Conductors are the only power carrying path in a power cable. Conductors are of different materials. Mainly in cable industry we use copper (ATC, ABC) and aluminium conductors for power cables. There are different types of  conductor as Class 1: solid, Class 2  stranded, Class 5 flexible, Class 6 Extra flexible (Mostly used for cords & welding) etc. Conductor sizes are identified with conductor resistance.
INSULATION
The insulation provided on each conductor of a cable by mainly PVC (POLY VINYL CLORIDE ), XLPE (CROSSLINKED POLYETHYELENE), RUBBER (VARIUS TYPES OF RUBBER ). Insulating material is based on operating temperature. 
Cores are identified by colour coding by using different colours on insulation or by number printing on cores  
BEDDING (INNER SHEATH)
This portion of the cable is also known as inner sheath. Mostly it is used in Multi core cables. It works as binder for insulated conductors together in multi-core power cables and provides bedding to armour/braid. This portion of the cable is mainly made of PVC( PVC ST-1, PVC ST-2 ), RUBBER (CSP SE-3, CSP SE-4 & PCP SE-3, PCP SE-4, HOFR SE-3 HOFR SE-4, HD HOFR SE-3 ETC)
ARMOURING
There are mainly G.I. WIRE ARMOURING, G.I. STEEL STRIP armouring. It is done by placing G.I. WIREs, GI or STEEL STRIPs one by one on inner sheath. Armouring is a process which is done mainly for providing earthing shield to the current carrying conductors as well as it is also used for earthing purpose of the cable for safety. When there is any insulation failure in the conductor, the fault current gets enough paths to flow through the armour if it is properly earthed. Providing extra mechanical protection and strength to cable an important added advantage of armouring. In MINING CABLES it is done for conductance 
BRAIDING
ANNEALED TINNED COPPER WIRE , NYLON BRAID , COTTON BRAID are mainly used for this purpose. Braiding is the process which gives high mechanical protection to cable and also used for earthing purpose. Significance of braiding is it is more flexible in comparison to armouring.   
OUTER SHEATH
This is outermost cover of the cable normally made of PVC (POLYVINYL CLORIDE ), RUBBER (VARIUS TYPES OF RUBBER) and often the same material as the bedding. It is provided over the armour for overall mechanical, weather, chemical and electrical protection. Outer sheath is protection offered to cable not much electrically but more mechanically.

Electrical power cable

Reviewed by Bibi Mohanan on February 19, 2016 Rating: 5

Parts of a Power transmission line and Transmission tower

Bibi Mohanan February 19, 2016

Transmission line parts

1. Insulator.

2. Bundle of two conductors (some lines have 4).

3.Spacer to hold the two conductors apart.

4. Earth wire at top of tower or pylon.

5. The three bundles on one side of the tower make up one electrical circuit. Most lines have two circuits, one each side.

6.Identity plate saying which line it is and who owns it. Also usually has a safety warning notice about the dangers of electrocution.

7.Anti-climbing device - barbed wire to stop unauthorised climbing

Transmission tower -

A power transmission tower consists of the following parts, 1) Peak of transmission tower 2) Cross arm of transmission tower 3) Boom of transmission tower 4) Cage of transmission tower 5) Transmission Tower Body 6) Leg of transmission tower 7) Stub/Anchor Bolt and Base plate assembly of transmission tower. The main parts among these are shown in the pictures.

Types of Transmission Tower

According to different considerations, there are different types of transmission towers. The transmission line goes as per available corridors. Due to unavailability of shortest distance straight corridor transmission line has to deviate from its straight way when obstruction comes. In total length of a long transmission line there may be several deviation points. According to the angle of deviation there are four types of transmission tower- 1. A – type tower – angle of deviation 0^o to 2^o. 2. B – type tower – angle of deviation 2^o to 15^o. 3. C – type tower – angle of deviation 15^o to 30^o. 4. D – type tower – angle of deviation 30^o to 60^o.

Parts of a Power transmission line and Transmission tower

Reviewed by Bibi Mohanan on February 19, 2016 Rating: 5

Difference between earthing and grounding

Bibi Mohanan February 19, 2016

Grounding is the commonly word used for earthing in the North American standards like IEEE, NEC, ANSI and UL etc while, Earthing is used in European, Common wealth countries and Britain standards like IS and IEC etc.

Ground is a source for unwanted currents and also as a return path for main current. While earthing is done not for return path but only for protection of delicate equipments. It is an alternate low resistance path for current. Earth is used for the safety of the human body in fault conditions while Grounding (As neutral earth) is used for the protection of equipments.

Earthing:

· Earthing means connecting the dead part (it means the part which does not carries current under normal condition) to the earth for example electrical equipment’s frames, enclosures, supports etc.

· The purpose of earthing is to minimize risk of receiving an electric shock if touching metal parts when a fault is present. Generally green wire is used for this as a nomenclature.

· Under fault conditions the non-current carrying metal parts of an electrical installation such as frames, enclosures, supports, fencing etc. may attain high potential with respect to ground so that any person or stray animal touching these or approaching these will be subjected to potential difference which may result in the flow of a current through the body of the person or the animal of such a value as may prove fatal.

· To avoid this non-current carrying metal parts of the electrical system are connected to the general mass of earth by means of an earthing system comprising of earth conductors to conduct the fault currents safely to the ground.

· Earthing has been accomplished through bonding of a metallic system to earth. It is normally achieved by inserting ground rods or other electrodes deep inside earth.

· Earthing is to ensure safety or Protection of electrical equipment and Human by discharging the electrical energy to the earth.

Grounding:

· Grounding means connecting the live part (it means the part which carries current under normal condition) to the earth for example neutral of power transformer.

· Grounding is done for the protections of power system equipment and to provide an effective return path from the machine to the power source. For example grounding of neutral point of a star connected transformer.

· Grounding refers the current carrying part of the system such as neutral (of the transformer or generator).

· Because of lightening, line surges or unintentional contact with other high voltage lines, dangerously high voltages can develop in the electrical distribution system wires. Grounding provides a safe, alternate path around the electrical system of your house thus minimizing damage from such occurrences.

· Generally Black wire is used for this as a nomenclature.

All electrical/electronic circuits (AC & DC) need a reference potential (zero volts) which is called ground in order to make possible the current flow from generator to load. Ground is May or May not be earthed. In Electrical Power distribution it is either earthed at distribution Point or at Consumer end but it is not earthed in Automobile( for instance all vehicles’ electrical circuits have ground connected to the chassis and metallic body that are insulated from earth through tires). There may exist a neutral to ground voltage due to voltage drop in the wiring, thus neutral does not necessarily have to be at ground potential.

In a properly balanced system, the phase currents balance each other, so that the total neutral current is also zero. For individual systems, this is not completely possible, but we strive to come close in aggregate. This balancing allows maximum efficiency of the distribution transformer’s secondary winding

The small difference between earthing and grounding concept is:-

§ There is no major difference between earthing and Grounding, both means “Connecting an electrical circuit or device to the Earth”. This serves various purposes like to drain away unwanted currents, to provide a reference voltage for circuits needing one, to lead lightning away from delicate equipment. Even though there is a micro difference between grounding & earthing.

Difference between earthing and grounding

Reviewed by Bibi Mohanan on February 19, 2016 Rating: 5

Ho to make earth pit and do earthing in home

Bibi Mohanan February 19, 2016

How to make earth pit.

1. Excavation on earth for a normal earth Pit size is 1.5M X 1.5M X 3.0 M

2. Use 500 mm X 500 mm X 10 mm GI Plate (Plate may be use as big as possible to contact more and more area of Earth for low resistance & best result)

3. Make a mixture of Wood Coal Powder Salt & Sand all in equal part
(a) Wood Coal Powder use as good conductor of electricity, anti corrosive, rust prove for GI Plate for long life.
(b) Salt use as electrolyte to form conductivity between GI Plate Coal and Earth with humidity
(c) Sand has used to form porosity to cycle water & humidity around the mixture

4. Put GI Plate (EARTH PLATE) of size 500 mm X 500 mm X 10 mm in the mid of mixture

5. Use Double GI Strip size 30 mm X 10 mm to connect GI Plate to System Earthling

6. It will be better to use GI Pipe of size 2.5" diameter with a Flange on the top of GI Pipe to cover GI Strip from EARTH PLATE to Top Flange

7. Cover Top of GI pipe with a T joint to avoid jamming of pipe with dust & mud and also use water time to time through this pipe to bottom of earth plate

8. Maintain less than one Ohm Resistance from EARTH PIT conductor to a distance of 15 Meters around the EARTH PIT with an other conductor dip on the Earth at least 500 mm deep.

9. Check Voltage between EARTH PIT conductor to Neutral of Mains Supply 220V AC 50 Hz it should be less than 2.0 Volts

Ho to make earth pit and do earthing in home

Reviewed by Bibi Mohanan on February 19, 2016 Rating: 5

How to make an extension box

Bibi Mohanan February 19, 2016

Here, I am going to discuss about how to make an extension box , containing 3 switchess and three plug sockets. The circuit lay out is as shown below.