New Year: नए साल पर करियर में लाना है बदलाव तो जरूर ध्यान में रखें ये बातें
तेजी से बदलते इस दौर में खुद को ढालने के लिए अपने स्किल्स पर लगातार काम करते रहना चाहिए.
NOTES&BOOKS For Electrical,Instruments,Automation,Travel & Mind tools
Dec 23, 2017
The distant star called RZ Picseum located in the constellation Pisces – is an insatiable ‘eater of worlds’. (Image Source: NASA)
The distant star called RZ Picseum located in the constellation Pisces
The distant star called RZ Picseum located in the constellation Pisces – is an insatiable ‘eater of worlds’. (Image Source: NASA)
NASA eyes 3D-printing technology
NASA eyes 3D-printing technology
By 3-D printing the hardware, more than 100 welds were eliminated, reducing costs by nearly 35 per cent and production time by more than 80 per cent. (Image Source: NASA)
AS NASA builds its most powerful rocket, the Space Launch System (SLS), the US space agency is testing engines with 3D-printed parts to cut costs of powering the heavy-lift rocket. A major milestone towards that end was achieved this month when engineers successfully hot-fire tested an RS-25 rocket engine with a large 3-D printed part, the US space agency said on Friday.
The 3-D printed part, called the pogo accumulator, is a beachball-sized piece of hardware that acts as a shock absorber by regulating liquid oxygen movement in the engine to prevent the vibrations that can destabilise a rocket’s flight, NASA said. By 3-D printing the hardware, more than 100 welds were eliminated, reducing costs by nearly 35 per cent and production time by more than 80 per cent.
Initial reports show the 3-D printed hardware performed as expected, opening the door for more components scheduled for future tests, the US space agency said. The test was part of the SLS Programme’s RS-25 affordability initiative – a collaborative effort between NASA and industry partner Aerojet Rocketdyne of Canoga Park, California, to reduce the engine’s overall production costs while maintaining performance, reliability and safety.
“As we build future RS-25s, NASA and our partners are taking advantage of innovative manufacturing techniques, including additive manufacturing, or 3-D printing, to make the engines more affordable,” said Andy Hardin of NASA’s Marshall Space Flight Center in Huntsville, Alabama. “3-D printing is revolutionising manufacturing, and the pogo accumulator is the first of many components that can be built more quickly and less expensively,” Hardin said.
To minimise the costs of developing SLS, NASA selected the RS-25 engine. “With modern fabrication processes, including additive manufacturing, the ‘next generation’ of the RS-25 will have fewer parts and welds, reducing production time as well as costs,” said Carol Jacobs, RS-25 engine lead at Marshall.
The test was part of the SLS Programme’s RS-25 affordability initiative – a collaborative effort between NASA and industry partner Aerojet Rocketdyne of Canoga Park, California. (Image Source: NASA)
“Reducing the number of welds is very important,” she said. “With each weld comes inspections and possible rework. By eliminating welds, we make the hardware more reliable and the process much more lean and efficient, which makes it more cost-effective,” Jacobs said. The SLS Program has ordered six new engines to be built by Aerojet Rocketdyne for future flights.
The test conducted on December 13 was the first in a series of four tests designed to evaluate the operation of the 3-D printed pogo accumulator, and the first in the series to certify the next generation of RS-25 engines. The new, pogo accumulator will be included on all tests moving forward, NASA said.
“Future tests will incorporate more and more 3-D printed components, with each test series building on the previous tests,” said Hardin. The first SLS flight is scheduled to take place no earlier than 2019, but NASA recently stated that this launch could be pushed back to 2020 depending on the manufacturing and production schedule, Space.com reported.
This flight will use SLS to send an un-crewed Orion spacecraft around the moon and back to Earth. A crewed mission will follow later, in the 2020s.
Travel without a cause: Break free of the conventional journey
To journeys where you savour time and break free of the rigours of contemporary travel
Before leaving, there had been the question, “What do you plan to do?”
Unfortunately, there was no plan. I was fairly certain that I was on a holiday — I had applied for four days work leave. But I had very little desire to “travel”. The plan, if one can call it that, was to simply visit a friend who I hadn’t seen in years. I’d stay with him, his family including two adorable dogs, at his 100-year-old house at Kangra, Himachal Pradesh.
Discover Paradise in Pantanal on your Brazil Tour
Discover Paradise in Pantanal on your Brazil Tour
On your Brazil Tour, plan a stop in Pantanal North. A true paradise for nature lovers and those with an adventurous spirit, be prepared for an enchanting encounter with nature’s untouched beauty.
SELECTION OF MCB / MCCB ( LESSON-1)
SELECTION OF MCB / MCCB
Introduction
MCB or MCCB are widely used in electrical distribution system for ON/OFF Electrical supply and it also gives over current and short circuit protection. Selection of MCB or MCCB involved technical, Mechanical parameters. Some parameters are important but some parameters are confusing and mislead to wrong selection of MCCB. Some parameters are directly affected on cost of MCCB.
Specification / Name Plate Details of MCB/MCCB:
Following specifications are required to select appropriate MCB or MCCB.
(A) Current Related:
- Frame Size (Inm): Amp
- Rated current (In/ Ie): Amp
- Ultimate short circuit breaking capacity (Icu): KA
- Rated short-circuit breaking capacity (Ics): % of Icu
(B) Voltage Related:
- Rated voltage (Ue): Volt
- Rated Insulation voltage (Ui): Volt
- Rated impulse withstand voltage(Uimp): KV
- No’s of Pole : SP,DP,TP,TPN,FP
(C) Application Type:
- Utilization Category/ Characteristic : B,C or D curve
(D) Accessories:
- Rotary Handle: Extended/ Direct
- Alarm Contact:
- Shunt Trip:
- Under voltage Trip:
- Mechanical interlocking:
- Manual /Auto operation
- Motorized Operation:
(E) Protection Type:
- Protection : Over current / Short circuit
- Trip Mechanism: Thermal / Magnetic / Solid / Microprocessor
- Trip Mechanism adjustment : Fixed / Adjustable
(F) Others:
- Frequency;
- Reference temperature: (if different from 30°C)
- Pollution degree:
- Suitability for isolation:
- Type of Mounting arrangement
- Electrical Life Cycles:
- Mechanical Life Cycles:
- Dimension: mm
- Weight: Kg
- Reference Standard: IEC: 60947-1/2, IS: 13947-1/2
(A) Current Related:
(1) Frame Size (Inm):
- Breaker Frame Size indicates the basic framework of the Plastic shell of MCCB that can hold the biggest rated current.
- It is the maximum current value for which the MCCB is designed (upper limit of the adjustable trip current range) and it also determines the physical dimensions of the device.
- There are varieties current ratings MCCB for the same series frame Size.
- For example, DX100 Frame Size MCCB for rated current of 16A, 20A, 25A, 32A, 40A, 50A, 63A, 80A, 100A.
- Same DX225 Frame Size MCCB for rated current of 100A, 125A, 160A, 180A, 200A, 225A.
- In above DX100 and DX225 has two Type of frame Size for rated current of 100A, but the shape and size of breaking capacity of circuit breakers is not the same.
(2) Rated Current (In /Ie):
- It is the current value above which overload protection is tripped.
- For MCB it is fixed while in MCCB the rated current is an adjustable range instead of a fixed value.
- Standard rating of MCB is 1A, 2A, 3A, 4A, 6A, 10A, 13A, 16A, 20A, 25A, 32A, 40A, 50A, 63A, 100A for MCB.
(B) Voltage Related:
(3) Ultimate short-circuit breaking capacity (Icu):
- Breaking capacity can be defined as the maximum level of fault current which can be safely cleared.
- It is the highest fault current that the MCCB can trip without being damaged permanently.
- The MCCB will be reusable after interrupting a fault, as long as it doesn’t exceed this value.
- It is indicate operation reliability of MCCB
- This parameter may increase or decrease the cost, so it should be properly decided. Breaking capacity should be higher than the possible fault level. For domestic application fault level may be 10kA.
(4) Operating short-circuit breaking capacity (Ics):
- It is expressed as a percentage ratio of Icu and tells you the maximum short-circuit current if a circuit breaker can break three times and still resume normal service.
- The higher the lcs, the more reliable the circuit breaker
- It is the maximum possible fault current that the MCCB can clear. If the fault current exceeds this value, the MCCB will be unable to trip and another protection mechanism must operate.
- If a fault above the Ics but below the Icu occurs, the MCCB can interrupt it successfully but will need a replacement due to the damage suffered.
- The Main difference between Ultimate Short Circuit (Icu) and Service Breaking Capacity (Ics) that Icu (Ultimate Braking Capacity) means Circuit breaker can remove the fault and remain usable but Ics (Service Braking Capacity) means Circuit breaker can remove the fault, but it may not be usable afterwards.
- For example, if a circuit breaker has an Ics of 25,000 Amperes and an Icu of 40,000 Amperes:
- Any fault below 25kA will be cleared with no problem.
- A fault between 25kA and 40kA will cause permanent damage when cleared.
- Any current exceeding 40 kA can’t be cleared by this breaker.
(5) Rated working voltage (Ue):
- It is the continuous operation voltage for which the MCCB is designed.
- This value is typically equivalent or close to a standard system voltage.
- In three phase it is usually 400V or 415 V. For single phase it is 230V or 240V.
(6) Rated Insulation voltage (Ui):
- It is the maximum voltage that the MCCB can resist according to laboratory tests.
- It is higher than the rated working voltage, in order to provide a margin of safety during field operation.
(7) Rated impulse withstands voltage (Uimp):
- It is the value of transient peak voltage the circuit-breaker can withstand from switching surges or lighting strikes imposed on the supply.
- This value characterizes the ability of the device to withstand transient over voltages such as lightning (standard impulse 1.2/50 μs).
- Uimp = 8kV means Tested at 8 kV peak with 1.2/50μs impulse wave.
(8) Number of Poles:
- No of Pole for MCCB depends on Single Phase & Three Phase Power Controlling /Protection
- Single Pole (SP) MCB:
- A single pole MCB provides switching and protection for one single phase of a circuit.
- Used: for Single Phase circuit
- Double Pole (DP) MCB:
- A two Pole MCB provides switching and protection both for a phase and the neutral.
- Used: for Single Phase circuit
- Triple Pole (TP) MCB:
- A triple/three phase MCB provides switching and protection only to three phases of the circuit and not to the neutral.
- Used: for Three Phase circuit
- 3 Pole with Neutral (TPN (3P+N) MCB):
- A TPN MCB, has switching and protection to all three phases of circuit and additionally Neutral is also part of the MCB as a separate pole. However, Neutral pole is without any protection and can only be switched.
- Used: for Three Phase circuit with Neutral
- 4 Pole (4P) MCB:
- A 4 pole MCB is similar to TPN but additionally it also has protective release for the neutral pole. This MCB should be used in cases where there is possibility of high neutral current flow through the circuit as in cases of an unbalanced circuit.
- Used: for Three Phase circuit with Neutral
Read also
Read also
How are field device wired to PLC/DCS Part 1
How are field device wired to PLC/DCS Part 1
Measuring Principle Capacitance
Capacitance level instruments can be used for point level detection and continuous level measurement, particularly in liquids. The measuring principle is based on the change of the capacitance in a capacitor. The electrically conductive tank wall and a probe inside of the tank form a capacitor, the capacity changes of which are used to determine the level. This animation shows the measuring principle in conductive liquids and non-conductive liquids.
Next generation of electric vehicles- How does an Electric Car work ?
Next generation of electric vehicles- How does an Electric Car work ?
Electric cars are making big waves in the automobile world. These noise-free, pollution-free and high-performance vehicles are expected to make their I.C. engine counterparts obsolete by 2025. This video will unveil the hidden technologies behind the Tesla Model S, which recently became the world’s fastest accelerating car. We will see how electric cars have achieved superior performance by analyzing the technology
Dec 22, 2017
65 Most Inspirational Quotes for All
Inspirational Quotes
Here they are, the most inspirational quotes ever uttered, sure to stir you and get you moving through the day.Whether you feel stuck or just need a good dose of inspiration from great minds, these should do the trick. Be sure to feed your brain inspiring quotes and phrases daily, since it needs to be fed regularly just like the rest of your body.
PROTECTION SETTING OF MCCB (LESSON-2)
Over load , Shirt circuit & Ground Fault Protection (LESSON-2)
(2) For Short Circuit Protection (Magnetic Setting):
(C) Short Time pickup Current Setting (Im):
- Short time protection is time-independent.
- It is determines or sets the level of fault current at which the short-time trip delay countdown is actuated.
- Short Time Pick up Value (Im) (multiplied by the ampere rating) sets the short circuit current level at which the circuit breaker will trip after the set time delay.
- The short-time pickup (Isd) sets current level (below instantaneous trip level) at which circuit breaker will trip after the preset time delay.
- Standard Practice for Setting:
- No trip for a current below 80% of the short time setting
- Trip for a current equal to 120% of the short time setting
- The trip time is Less than 0.2 s for a short time protection with no time delay and equal to the value of the time delay tsd for a protection with time delay
PROTECTION SETTING OF MCCB (LESSON-1)
Protection setting of MCCB ( Over load , Shirt circuit & Ground Fault Protection (LESSON-1)
Introduction:
- There are various types of protections setting in MCCB, which define various protection of Electrical Network.
- In MCCB we can set most of protection are adjustable according to Electrical Load profile.
- The main adjustable Setting in MCCB are
- Over current Setting
- Short Circuit Setting
- Ground Fault Setting
Meaning of each selector switches of MCCB
- As Per Standard IEC 60947-2 defines the names of the selector switches.
| Setting | Adjustment | Protection For |
| Ir | Long time Pick up Current Setting (or thermal Setting). This is a multiplication coefficient of the rating of the device. (Ir=xIn) | Protection against overloads |
| tr | Long time delay Setting in seconds, enabling in particular the starting current of a motor to be tolerated. (tr=Sec) | Protection against overloads |
| Im / Isd | Short time (Magnetic Setting). This is a multiplier of the Ir setting, often 1.5 to 10 times the Ir current (im=xIr) | Protection against short circuits. |
| tm / tsd | Short time delay Setting, enabling in particular the discrimination (time) to be increased with downstream feeders and the magnetization peaks of a transformer or a motor to be tolerated. It is recommended that the I²t selector switch is set to the ON position.(tm=Sec) | Protection against short circuits. |
| Ii | Instantaneous current Setting. Protecting the installation against strong short circuits (dead short circuits) by instantaneous tripping without Time Delay and self-protection of the circuit breaker.
The Ii > Isd.
| Protection against Dead Short circuits. |
| Ig | for monitoring the earth fault current circulating in the Phase and Earth conductor in TNS systems | Earth protection |
| tg | Earth protection time delay | Earth protection |
| I delta n | Adjustment of the sensitivity of the earth leakage protection | Earth leakage protection |
| delta t | Earth leakage protection delay. | Earth leakage protection |
Setting of each Protection switch of MCCB
(1) For Low level Fault / Over Current Protection (Thermal Setting):
(A) Long-Pickup Current Setting (Ir):
- It is determines the continuous ampere rating of the breaker.
- Long time protection is time-dependent.
- Long Pickup (Ir) value (multiplied by the ampere rating (In) of MCCB) sets the maximum current level which the circuit breaker will carry continuously.
- If MCB is 1000A Rating but Full Load current is 800A than MCCB Rating can be changed from 1000A to 800A by setting it 0.8, Now Ir=0.8XIn =0.8×1000=800Amp
- If the current exceeds this value for longer than the circuit breaker will trip at the set delay time.
- Long time protection is inverse time type (with I2t constant)
- The long-time pickup (Ir) is adjustable from 4 to 1.0 times the sensor plug rating (In)
- Standard Practice for Setting:
- No trip for a current below 105% of Ir
- Trip in less than two hours for a current equal to for
- 120% of Ir for an electronic trip unit and for
- 130% of Ir for a thermal-magnetic trip unit
- For a higher fault current, the trip time is inversely proportional to the fault current value.
(B) Long-Time delay Setting (tr):
- Long time delay (tr) sets length of time that the circuit breaker will carry a sustained overload before tripping.
- The delay bands are labeled in seconds of over current at six times the ampere rating.
- Long-time delay is an inverse time characteristic in that the tripping time decreases as the current increases.
- The long-time delay (tr) sets the length of the time that the circuit breaker will carry an over current (below the short-time or instantaneous pickup current level) before tripping.
- The Long time delay can be set to I2t On and I2t OFF settings.
- (A) I2t Response:I2t Out ,For coordination with other circuit breakers with electronic trip devices and for coordination with thermal-magnetic circuit breakers.
- (B) I2t Response: I2t In ,For coordination with fuses and upstream transformer
KNOW BEFORE BUYING LED BULBS ( LESSON :3)
know before buying LED Bulbs
(4) Color Rendering Index (CRI):
- There are two standard measurements for the color characteristics of light: “color rendering index” (CRI) and “color temperature”, which expresses the color appearance of the light itself.
- Color rendering index measures the ability of a light bulb to reproduce colors.
- CRI is described How artificial light source is able to render the true color of objects as seen by natural outdoor sunlight which has a CRI of 100
KNOW BEFORE BUYING LED BULBS ( LESSON :2)
know before buying LED Bulbs ( LESSON :2)
(3) Correlated Color temperature (CCT):
- Color temperature refers to the light’s color characteristics.
- Color Temperature is measured in Kelvin.
- It refer to the warmness or coolness of the light that bulb produces.
- The color temperature of a light source is a numerical measurement of its color appearance.
- This temperature is based on the principle that any object will emit light if it is heated to a high enough temperature and that the color of that light will shift in a predictable manner as the temperature is increased.
- Color temperature is a description of the warmth or coolness of a light source. When a piece of metal is heated (temperature increases) the color of light it emits will change. This color begins as red in appearance and graduates to orange, yellow, white, and then blue-white to deeper colors of blue.
- Color Temperature is not an indicator of lamp heat.
- The sun, for example, rises in morning at approximately 1800 Kelvin and changes from red to orange to yellow and to white as it rises to over 5000 Kelvin at high noon. It then goes back down the scale as it sets in evening.
- The warm white ranges from about 2700k to 3800k, natural white ranges from 3800k to 4800k, pure white or daylight from about 4800k to 6000k. Cool white starts from around 6000k upwards.
- Colors and light sources from the red/orange/yellow side of the spectrum are described as warm (incandescent) and those toward the blue end are referred to as cool (natural daylight).
- In Color Temperature Value higher Kelvin temperatures (3600–5500 K) are consider cool and lower color temperatures (2700–3000 K) are considered warm.
- When choosing a color, the two considerations are important one is color rendering (How well the light shows the true color of objects) and temperature.
(1) Soft White / Warm White (2700K- 3000K):
- Warm light is preferred for living spaces because it is more flattering to skin tones and clothing.
- Recommended for indoor general and task lighting applications.
- Living rooms
- Bed rooms
- Rooms decorated in earthy tones (reds, oranges, and yellows)
- It gives effect like incident or halogen Light.
(2) Natural / Cool White (3500K- 4500K):
- Cool light is preferred for visual tasks because it produces higher contrast than warm light.
- Recommended for use in Domestic Applications.
- Warmer Whites are preferable in living and dining areas as well as reception areas to create a more relaxed environment.
- Natural Whites are preferable for kitchens and bathrooms where tasks are performed.
- Suitable for work areas where contrast is important.
- Kitchen
- Bath rooms
- Rooms decorated in airy, fresh hues (blues, greens, whites)
- It gives effect like Fluorescent Light.
(3) Bright White (4500-5000K):
- Recommended for use in:
- Office
- Study Room
(4) Daylight / Full Spectrum (5000K- 6500K):
- Recommended for use in:
- Garage
- Office
- Industrial and hospital areas.
| Lighting Source CCT | |
| Source | Color temperature in Kelvin |
| Skylight (blue sky) | 12,000 – 20,000 |
| Average summer shade | 8000 |
| Light summer shade | 7100 |
| Typical summer light (sun + sky) | 6500 |
| Daylight fluorescent | 6300 |
| Xenon short-arc | 6400 |
| Overcast sky | 6000 |
| Clear mercury lamp | 5900 |
| Sunlight (noon, summer, mid-latitudes) | 5400 |
| Design white fluorescent | 5200 |
| Special fluorescents used for color evaluation | 5000 |
| Daylight photoflood | 4800 – 5000 |
| Sunlight (early morning and late afternoon) | 4300 |
| Brite White Deluxe Mercury lamp | 4000 |
| Sunlight (1 hour after dawn) | 3500 |
| Cool white fluorescent | 3400 |
| Photoflood | 3400 |
| Professional tungsten photographic lights | 3200 |
| 100-watt tungsten halogen | 3000 |
| Deluxe Warm White fluorescent | 2950 |
| 100-watt incandescent | 2870 |
| 40-watt incandescent | 2500 |
| High-pressure sodium light | 2100 |
| Sunlight (sunrise or sunset) | 2000 |
| Candle flame | 1850 – 1900 |
| Match flame | 1700 |
| Skylight (blue sky) | 12,000 – 20,000 |
| Average summer shade | 8000 |
| Light summer shade | 7100 |
| Typical summer light (sun + sky) | 6500 |
| Daylight fluorescent | 6300 |
| Xenon short-arc | 6400 |
| Overcast sky | 6000 |
| Clear mercury lamp | 5900 |
| Sunlight (noon, summer, mid-latitudes) | 5400 |
| Design white fluorescent | 5200 |
| Special fluorescents used for color evaluation | 5000 |
| Daylight photoflood | 4800 – 5000 |
| Sunlight (early morning and late afternoon) | 4300 |
| Bright White Deluxe Mercury lamp | 4000 |
| Sunlight (1 hour after dawn) | 3500 |
| Cool white fluorescent | 3400 |
| Photoflood | 3400 |
| Professional tungsten photographic lights | 3200 |
| 100-watt tungsten halogen | 3000 |
| Deluxe Warm White fluorescent | 2950 |
| 100-watt incandescent | 2870 |
| 40-watt incandescent | 2500 |
| High-pressure sodium light | 2100 |
| Sunlight (sunrise or sunset) | 2000 |
| Candle flame | 1850 – 1900 |
| Match flame | 1700 |
CCT – Correlated Color Temperature
| |||
| Kelvin | Associated Effects | Type of Bulbs | Appropriate Applications |
| 2700° | Warm White, Very Warm White | incandescent bulbs | Homes, Libraries, Restaurants |
| 3000° | Warm White | most halogen lamps, Slightly ‘whiter’ than ordinary incandescent lamps | Homes, Hotel rooms and Lobbies, Restaurants, retail Stores |
| 3500° | White | Fluorescent or CFL | Executive offices, public reception areas, supermarkets |
| 4100° | Cool White | Office, classrooms, mass merchandisers, showrooms | |
| 5000° | Daylight | Fluorescent or CFL | Graphic industry, hospitals |
| 6500° | Cool Daylight | Extremely ‘white’ | Jewelry stores, beauty salons, galleries, museums, printing |
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