MCB Tripping Characteristics and applications of MCB'S

There are lot of MCB's available in the market. We can select the same according to load application.

MCB's Characteristics are discussed in detail below. You may easily select the MCB depending upon load.

‘B’ Curve: 

These type of MCB’S Short circuit release is set at 3-5 Rated current these type of MCB’S are used for protection of electrical circuits with equipment that does not cause surge current i.e. these type of MCB’S can be used for lighting and distribution circuits.

‘C’ Curve:

 These type of MCB’S Short circuit release is set at 5-10 Rated current these type of MCB’S are used  for protection of electrical circuits with equipment that causes surge current i.e. these type of MCB’S can be used for Inductive and Motor circuit loads.

‘D’ Curve: 

These type of MCB’S Short circuit release is set at 10-20 Rated current these type of MCB’S are used  for protection of electrical circuits with equipment that are having High inrush current . That Type of MCB’s can be used for Welding set Transformers, X-Ray Machines, Capacitor banks etc.

 ‘K’ Curve:

These types of MCB’S are Suitable for applications where high levels of inrush current are expected. 

These type of MCB’s used of loads which have Instantaneous trip is 8 - 12 In.

Theses have high magnetic trip point and are ideal for motors and transformers.

The narrow range (compared with the type D curve) makes it ideal for applications where nuisance tripping is not an issue.

‘Z’ Curve:

These type MCB’S have instantaneous trip at 2-3 In and are Suitable for applications where semiconductors and other components that fail open are used.

The short thermal delay and low magnetic trip point are ideal for applications where devices and components have low surge and short circuit tolerances.

‘S’ Curve:

These are suitable for applications with highly inductive loads

These type of MCB’S are especially used in control circuits with coils and light filaments.

 Instantaneous response between (13 - 17) In.

NH Types fuses or Bussmann fuses; Most widely used fuse

NH types fuses which are also known as Bussmann Fuses are most widely used all over industries and they comes up to rating of 1.25 kA. 

NH fuse links are designed for the protection of conductors and motors. The gL-gG characteristic fuse links are generally used to protect cables and installation lines from overloads and short-circuits. 

The aM characteristic fuse links are used for the short-circuit protection of motors and switchgear. 

They have applications in Electrical systems at:-

1. Electrical substations 

2. Electrical Panels

3. At Main Houses power supply 

NH fuses are manufactured in several current rating ranges. NH Fuses have character ending from 0 to 4a which depends upon rating of fuses and describe length of blade of fuse:-

Size	Current range (A)	Approx. blade length (mm)
00/000	6–160	78
0	6–160	125
1	80–250	135
2	125–400	150
3	315–630	150
4	500–1,000	200
4a	500–1,250	200

Electricity Saving tips; How to save electricity

We Consume lot of electricity without any effective utilization.

Below are the few tips which will surely help you to reduce your electricity bill.

•  Switch off Electricity supply when not in use e.g. we Switch off TV from Remote but not its power supply make a habit of switching off TV supply when not use as there is power drawn by TV even when it’s supply remains on. You might be thinking that how TV set draws power when switched off from remote. As electronic circuit consumes power whenever supply remains on. Similarly for Laptops, Computers, Greasers, Microwaves, Choppers, Mobile chargers etc.

              So Switch Off Supply of every device after use.

à Use CFL’S instead of Tube lights and Bulbs as CFL'S consumes lesser power, also in tube lights there are chokes which consumes more power. Also CFL having 15W rating provides illumination equals to that of 40W tube light. 

à Use coolers during starting of summers instead AC’S as coolers are effective at starting i.e. before rainy seasons.

àUse Energy efficient devices as new electrical and electronic appliances comes with Star rating, there is almost 100 W saving with per star rating which will results into higher cost recovery of higher star rating devices within 1 year.

àUse laptops, computers, Cellphones without wallpapers which will save electricity.

àUse water level switch for water motor so that motor will be switched off whenever water get filled.

àSet AC temp. between 22-25 degree Celsius In summers as this will reduce compressor loading and also leads to auto-stops of AC which will save electricity.

àService your AC before season start and assure cleaning of filter every week as it will lead to effective cooling and attaining the desired temp. quickly and will leads to saving of electricity.

àPut your monitor in sleep mode when not in use and even switch-off if possible.

àSwitch off all appliances before leaving to trip and even Refrigerator which normally no one does. Refrigerator consumes 500W to 1000W depending upon temp. setting so switch off your refrigerator as it will lead to huge saving for every trip. It is advisable also to switch-off main MCB of your house before leaving.

àDo temp. setting of refrigerator depending upon weather conditions.

These will results into lower down user electricity charges by some amount.

These are smart money saving tips with electricity usage which we can implement effectively without much effort.

Ingress protection of Equipments

Ingress Protection Rating is assigned to enclosures for degree of protection provided by them

The Ingress Protection rating normally has two numbers:-

1. Protection from solid objects or materials

2. Protection from liquids (water)

Ingress Protection First number - Protection against solid objects:-

0	No special protection
1	Protected against solid objects up to 50 mm, e.g. accidental touch by persons hands.
2	Protected against solid objects up to 12 mm, e.g. persons fingers.
3	Protected against solid objects over 2.5 mm (tools and wires).
4	Protected against solid objects over 1 mm (tools, wires, and small wires).
5	Protected against dust limited ingress (no harmful deposit).
6	Totally protected against dust.

Ingress Protection Second number - Protection against liquids

0	No protection.
1	Protection against vertically falling drops of water e.g. condensation.
2	Protection against direct sprays of water up to 15o from the vertical.
3	Protected against direct sprays of water up to 60o from the vertical.
4	Protection against water sprayed from all directions - limited ingress permitted.
5	Protected against low pressure jets of water from all directions - limited ingress.
6	Protected against temporary flooding of water, e.g. for use on ship decks - limited ingress permitted.
7	Protected against the effect of immersion between 15 cm and 1 m.
8	Protects against long periods of immersion under pressure.

e.g.

A motor having Ingress Protection of IP 65 is protected from:-
1. Total Protected from Dust
2. Protected against low Pressure jets of water from all directions i.e. limited Ingress

Now days Samsung has launched Smartphone S8 which is IP68 complied this means phone is Totally protected against dust and has protection against long periods of immersion under pressure.

Protection types for Hazardous Area in Oil & Gas Industry

Protection Types

Intrinsically Safety

The electrical energy available in circuits and equipment, is limited to a level to low to ignite the most easily ignitable mixtures in a hazardous area.Intrinsically safe barriers, as Zener, are installed in the circuit to limit current and voltage in the hazardous areas to avoid sparks or hot spots under fault conditions.

Encapsulation

The principle of this type of the protection is that the apparatus to be protected is submerged in a suitable substance in liquid state which is then allowed to cool and form a solid block. This avoids direct contact between the electrical apparatus and the explosive atmosphere

Pressurized Apparatus (Purged Apparatus)

In this type of protection the pressure inside the enclosure housing the electrical equipment is maintained at a positive pressure (higher than atmospheric pressure outside enclosure) so as not to allow ingress of inflammable gas mixture thus avoiding possibility of explosion.

Hazardous Zones Protection Techniques for Oil & Gas Industry

 Different protection techniques are used to address the hazardous zones :-

		ZONES
Ex d	Flameproof (Explosion proof) Enclosure	1, 2
Ex e	Increased Safety	1, 2
Ex ia	Intrinsically Safe	0, 1, 2
Ex ib	Intrinsically Safe	1, 2
Ex o	Oil Immersion	2
Ex p	Pressurized Apparatus (Purged Apparatus)	1, 2
Ex q	Powder Filling (Sand Filling)	2
Ex m	Encapsulation	1, 2
Ex n or Ex N	Non incentive or/and normally no sparking circuits	2

Explosion proof Gland and Difference between Explosion prrof and Double compression glands

 EXPLOSION PROOF GLANDS :-

Double compression explosion proof Glands are used in electrical equipment's for gland work of armored cable in compressor area,  glands usually have following construction features:-

1.Double Compression (Explosion proof Cable Glands-I,IIA,IIB)  

2.Material Brass (IS 319) -Standard. (AL/Mild Steel/SS. also available )

3.Threads ET"/BSC-Standards (In PG/Metric/NPT/BSP also available)

4.Sealing Ring Neoprene  

 Protection Class IP 66 as per IS 13947  

Pic Shows the Explosion proof Gland

Application Generally used in flammable Gas/ Vapour area (Gas I,IIA,IIB)  

EXPLOSION PROOF GLANDS PARTS:-

11. CHECK NUT 6 ARMOUR CLAMPING RING

22. WASHER 7 MAIN GLAND BODY

  3. NIPPLE ENTRY PART 8 NEOPRENE OUTER RUBBER

44. NEOPRENE INNER RUBBER 9 SKID WASHER

55. ARMOUR CLAMPING CONE 10 GLAND COVER

Main Difference between Explosion proof and Double compression glands is that Flameproof glands doesn't