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Industrial Electricity and Electronics
Industrial electricity and electronics refers to a trade which involves electrical wiring for residential, commercial and industrial applications. Strategic placements of wires and logic-boards installations are part of this profession.
525 Questions
In single phase applications, you have two wires. One of these is "hot", meaning it has an AC voltage applied to it. The other is not - it is directly tied to ground or the system neutral. In three phase power, all three wires are "hot", and use the other wires as the return path under balanced conditions.
Because of this you cannot do what you are proposing and have a safe setup. Isolating only two of the three wires still leaves one "hot".
Why used star contactor half value then main and delta contactor in star delta starter?
This type of motor starting configuration is used to start large motors. The utility company's policy is to only let a certain three phase motor horsepower loads across the line starting. High horsepower loads draw high current which draws the line voltage down. This causes a small instantaneous brown out to which the utility company gets complaints about. To solve this problem, limit the horsepower load. Starting a delta motor in star configuration reduces the inrush current because the voltage applied to the motor is lower.
This technology is rapidly becoming old due to the new type of motor controllers on the market. Replacing the star delta starters is soft start controllers. The inrush current can be controlled so as to not make any voltage drop on the line. These controllers are different from VFD's which are expensive for this type of application. The main function of the soft start is to get the motor on line without any line disturbances.
What symbols are in the poisonwood bible?
Methuselah, the Parrot
The parrot left by Brother Fowles serves as a symbol for the doomed Republic of Congo. Methuselah is denied freedom for most of his life, and while he is kept in a cage and fed by his masters, he loses the ability to fend for himself. Even after Nathan liberates him, Methuselah continues to stay close to the house he has always known, dependent on humans for his food. He even sleeps in their latrine at night, for fear of predators. Inevitably, the vulnerable Methuselah is ultimately caught by a civet cat, meeting his doom on the same day that the Republic of Congo begins its own short-lived independence. Within a few months the equally vulnerable nation will also be set upon by a predator, the United States, and killed.
The Demonstration Garden
Nathan's demonstration garden serves as a wonderful symbol on three levels. First the garden itself can be seen as a stand-in for the attitudes and beliefs that the Prices carry with them into Africa. Like those attitudes, the plants are wildly inappropriate in this environment. The plants become unrecognizable, almost grotesque in their hugeness. More significantly, though, they are rendered inert and useless, unable to fruit. The indigenous North American plants cannot vegetate under the conditions in Africa.
The very act of planting the garden rests upon one of the wildly inappropriate attitudes that the Prices carry with them. The venture reveals Nathan's blind arrogance, the belief that the Congolese are so backward that they have no idea how to grow their own food. It is beyond Nathan's capacity to reason that, if the climate permitted this sort of garden, Africans would have planted it themselves long ago. It does not occur to him to consider whether there is some reason, other than their utter stupidity and backwardness, which might account for the fact that there is little agriculture in Kilanga.
Finally, the garden is symbolic because of its biblical resonance. Gardens, in particular the Garden of Eden, play a prominent role in Christian tradition. It is in the Garden of Eden that Adam and Eve, the original man and woman, ate from the Tree of Knowledge thereby imbuing all future generations of human being with original sin. There is a clear irony in drawing a connection between Nathan's undertaking and Adam and Eve's. Adam and Eve sin by grasping for truth and knowledge that is not intended for them. Nathan, by contrast, sins through his willful ignorance, through his refusal to learn anything about the culture around him, and to enlarge and deepen his understanding of the world.
The Poisonwood Tree
Nathan first encounters the Poisonwood tree while planting his demonstration garden. Mama Tataba warns him not to touch the dangerous plant, but he contemptuously ignores her and ends up with painfully swollen arms and hands. The Poisonwood's primary role in the story, though, is in the form of a linguistic accident. In the native language the word "bangala" can mean "dearly beloved" if spoken slowly, or else "Poisonwood Tree" if spoken quickly. Unable to grasp this subtle linguistic distinction Nathan preaches week after week that Jesus is the local tree that can cause intense pain and even death. His thickheaded mistake is a result of his general inability or unwillingness to learn anything about the culture around him, a symptom of his general cultural arrogance. The mistaken phrase, however, is actually quite apt as a description of Jesus, at least in the hands of men like Nathan. That is, men who are so thickheaded and culturally arrogant that they could consistently make a mistake like this one for months on end. In such a context, Jesus really is a dangerous poison that can and did cause intense pain and even death.
Is wattmeter reading under no load test is equal to iron loss of the transformer?
Yes; that is the principle used in no-load tests on transformers. The current in the copper windings is zero on the secondary and low on the primary, so the copper loss is negligible.
Block digram of star delta starter?
Answers does not have the ability to reproduce diagrams on the answer page.
What is difference between in digital and Numerical Relay?
They seem to be the same thing. Such a device is a protective relay. It uses a microprocessor to analyze power system voltages, currents or other process quantities for the purpose of detecting faults in an industrial process system.
What are advantages of 200V 3ph motor over 380V 3ph?
In most applications 200v is easier to get for a supply voltage than 380v.
What does a 15 amp continuous duty rating mean for a power strip?
A 15 amp continuous duty rating for a power strip means that it can safely handle a constant load of up to 15 amps without overheating or causing damage. This rating ensures that the power strip is designed to handle sustained use without any issues.
Can a 125 HP 3 phase 460 volt saw be started with an across the line starter?
CAN and WILL BE ALLOWED TO are different questions.
Whether or not the motor CAN be started across the line will depend on the available short circuit current (SCC) at your location on the local utility's power distribution grid, and the rating of your service transformer. Check with your utility company. It may be possible to start the motor across the line, based on the transformer rating, but if there is not enough SCC, the utility will not allow you to connect the load without a starter or variable frequency drive system.
What is the potential difference across a single 4 Ohm resistor if the source voltage is 230v?
the potential difference across the single 4ohm resistor is 230volts.
The transformer size is calculated by using the load current that is required on the secondary side of the transformer. This secondary current is multiplied by the secondary voltage times 1.73. This total is then divided by 1000 to give you KVA. KVA = I x E x 1.73/1000.
Does a star delta timer rely on the breaking of the retaining contacts on the star contactor side?
The N.C. (timed open) contacts in the star delta timer energize the star contactor's coil when the system is energized. At the same instant the system is energized, the timer starts to time down the required time which lets the motor get up to speed in the star configuration. When the timer reaches the set point time, a second set of N.O. (timed closed) contacts close the delta contactor's coil and open the N.C. timed contacts of star contactor's coil. The motor now runs in the delta configuration. When the system is de energized the timer contact's reset to its de energized state.
What size of contactors used for 20hp star-delta starter?
The size of the contactors are dependant upon what the voltage the motor is operating on.
How does a 3 way manifold valve work?
If you mean by three-valve manifold, then
If you apply excessive pressure to your differential pressure transmitter, you could damage your instrument. This is known as over-ranging the transmitter.
A three-way manifold valve is a device that prevents the instrument from being over-ranged. It also allows the isolation of the transmitter from the process loop (an option which could be used generaly for maintenance or re-calibration or fitting new equipment).
It consists of two blocking valves and one equalizing valve. The blocking valves are for both high pressure and low pressure sides. During normal operation, the equalizing valve is closed and the blocking valves are open. When the transmitter is put into service, care should be taken to ensure that the high pressure is never applied to one side of the Differential Pressure Transmitter.
To put a DPT into service using the Three-way manifold valve is to first close all valves. Then, open the equalizing valve to ensure the same pressure will be applied on both sides of the transmitter. Therefore you will have a zero differential pressure.
Next, the high pressure block valve is opened slowly (to check for leakage from both sides of the transmitter). The equalizing valve is closed and this locks the pressure from both sides of the transmitter. Now open the low pressure block valve to apply the process pressure to the low pressure side and establish the working of the DPT.
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There are a few factors when wiring a workshop. The type of work shop and what is manufactured in it. Whether any types of chemicals or gasses will be present. Overall voltage and amperage that is to be used in the workshop. Whether there are any motor loads that are associated with the workshop.
These types of projects usually use a conduit system. The conduit system can be of three types. They can be PVC, EMT or Rigid conduit.
In Canada, Teck cable is used in these types of buildings installations. Using this type of a system keeps the labour costs lower than conduit systems.
If you want to explain the workshop in full detail by using the Discuss button on the left, a more detailed answer will be given.
What usually cause the star contactor to burn on a star delta starter?
A lot of designers will fit an under rated star contactor, partly for cost saving purposes and partly down to the fact that the star contactor will only stay energised for a brief period.
Burning out the star contactor could be down to it staying in circuit too long, not changing over to delta, a timer malfunction holding in the star contactor or switch that is defective in the control circuit.
Another cause could be your motor is drawing excess current.
Why is electrical air insulation worse at high altitude?
At high altitude air is less dense.
This means that any ionised air molecules (or charged pollution particles) in the air have less other air molecules (or pollution particles) to collide with as these ionised/charged particles accelerate towards the electrical conductors they are attracted to (with the opposite electric potential) .
As they have a better chance at accelerating for longer without being slowed down by colliding with other air molecules/ pollution particles (as they would in more dense air) they are able to reach higher speeds on average and so can cause a Townsend avalanche more easily
A Townsend avalanche is where a charged particles impact causes more charged particles to be created and these accelerate and impact with other particles creating more charged particles, a kind of chain reaction.
Note: there is actually a knee point in this trend, where if the pressure is reduced too much there are not enough molecule's/particles close together so an avalanche breakdown of the air is less likely to occur.
FYI: This effect is related to Paschen's law
