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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
What is the formula to calculate the current carrying capacity of bus bars?
Find out the volume of that object and then the mass of it and divide the mass by the volume to get the density.
Comment:
The answer given above is very wrong(in electricity).
Answer:
Bus bars carry high currents and thus a current transformer is used. It uses the bus bar as its primary winding and its wound section as its secondary winding. The magnetic flux of the bus bar due to its current is very small thus the current in the secondary windings will be small as well and safe to measure with a traditional Ammeter.
NB: These types of work must only be carried out by a qualified electrician. Don't put your life at risk.
What is the starting sequence of a star-delta starter?
This is the schematic for the starter. K1T is a timer. Initially KM1 and KM3 are closed to start the motor. Then KM2 is closed and KM1 is opened to run the motor This is the equivalent ladder logic using relays and timers.
Advantage of having a star - delta connected motor starter?
Whichever way it is connected, no matter whether it is in a star configuration or in a delta configuration, a 3-phase motor's start-up current can be more than 4 times its normal running current.
If the star configuration is used when first switching-on power to a 3-phase motor, a much smaller "start-up surge" is forced onto the power lines than if it were switched-on directly in the delta configuration.
So "using star for start-up" achieves very worthwhile purchase cost savings because smaller circuit breakers and thinner 3-phase line wire sizes can be installed to supply power to the motor.
However, leaving it running in star has a major disadvantage: the motor can never deliver as much power and torque as when it is running in delta.
For that reason a 3-phase motor was usually started in star mode and then - after reaching a steady speed - switched over to run in delta mode to achieve its maximum power output.
The explanation for this is easier to understand if you draw a sketch of the wirings and their connections, but unfortunately we cannot use diagrams when giving an answer here! Anyway, if you draw the circuit diagram for the windings connected in a "star" or "Y" configuration, it should look like a three-pointed star, with a phase input power line attached to each point of the star.
Thus, when a 3-phase motor's three windings are connected in a star configuration, the current from each individual phase power input line goes directly into one winding and is then series-connected to both of the other two windings via the star's "center-point".
If you draw the circuit diagram for a delta configuration, it should look like a triangle with a phase power input line attached to each point of the triangle.
Thus, when a 3-phase motor's three windings are connected in a delta configuration, each winding is effectively connected directly to two phase supply lines. The third phase supply line is also connected to that winding, but indirectly via the other two windings. They are connected in series to one another, and that series pair is connected in parallel across the first winding, to form the "delta".
The much lower starting current is the main reason why a three-phase motor was usually started in star mode and then - after gaining a steady speed - was switched over to run in delta mode to achieve its maximum power output.
Update: Electronic motor-control systems, which offer soft-starts in DELTA configuration, are now replacing the use of manual or semi-automatic star-delta starters.
Technical explanation
When the windings of a 3-phase motor are connected in STAR:
- the voltage applied to each winding is reduced to only (1 /.'/'3) [1 divided by root three] of the voltage applied to the winding when it is connected directly across two incoming power service lines in DELTA.
- the current per winding is reduced to only (1 /.'/'3) [1 divided by root three] of the normal running current taken when it is connected in DELTA.
- so, because of the Power Law V [in volts] x I [in amps] = P [in watts],
the total output power when the motor is connected in STAR is:
PS = [VL x (1/.'/'3)] x [ID x (1/.'/'3 )] = PD x (1/3) [one third of the power in DELTA]
where:
VL is the line-to-line voltage of the incoming 3-phase power service
ID is the line current drawn in DELTA
PS is the total power the motor can produce when running in STAR
PD is the total power it can produce when running in DELTA.
- a further disadvantage when the motor is connected in STAR is that its total output torque is only 1/3 of the total torque it can produce when running in DELTA.
For more information please see the answers to the Related Questions shown below.
Why motor is connected in star connection first in star delta starter?
To use a star delta starter, the motor must be a three phase six wire motor. The extra wires out are the wires that are usually terminated in the motor housing as the star point. The starter, when energized, brings the star contactor in and closes the star point coil ends. An external timer times out after the motor gets up to speed in the star connection and drops the star contactor and closes the delta contactor. When in the delta connection the motor coils are then paralleled to allow the motor to run at full voltage.
What is theConstruction difference between stream turbine and gas turbine?
gas turbines and gas engines are different in mechanic designes uses diffrent liquid for engine we use flemmable gas we use for turbine liquide flemmable but they need air both gas turbines and gas engines are different in mechanic designes uses diffrent liquid for engine we use flemmable gas we use for turbine liquide flemmable but they need air both answer by nailiyoucef05@yahoo.fr
I dont think so. Gas engine works as the same principle of a petrol engine. And in gas turbine gas is burned and high velocity gas is passed through the turbine.
A gas engine is an internal combustion engine and have no turbines.
alamm2@asme.org
How many amps can a 14 AWG wire carry?
A wire is not like a bucket that holds amps but more like a pipe that lets the amperage flow through it. A # 14 wire is rated at 15 amps. Code only allows up to 80% for continuous use, 15 x .8 = 12 amps.
What are the three types of electronic diagram?
what are the 3 kinds of electonic diagrams ..the three kinds are layout or block diagram, schematic diagram and pictorial diagram
What is the wattage rating of a 3 phase water pump?
To answer this question a voltage and HP must be stated.
How does a resistor in a circuit effect similar to open circuit?
Resistors resist amounts of the electricity flowing through the circuit.For example if the resister has these strips of colors on it in this order(red,green,blue) then the resister has 25,000,000 ohms. That means that the lamp(s)/ bulb(s) is(are) going to be very going to be very dim. Because, the more ohms the dimmer the light, the less ohms the brighter the light.
But we should get back on task. A resistor effects a circuit because it makes the lamp(s)/ bulb(s) brighter of dimmer depending on the amount of ohms they have.
What benefit does electric power have on factories?
To see this simply go to any old factory that was around before electric motors. You will see the reminants of an intricate power delivery system to drive rotating equipment. Long axles ran across the roof of the building, with power take off pullies every few feet. Each machine was powered from one of these pullies, so each machine had a belt running to it from the cieling. To stop and start an individual machine a clutch was needed, as stopping the steam engine or whatever else powered the whole plant was not an option. All the rotating equipment posed a huge safety hazard, and I'm willing to bet arms were lost to those belts. If a belt came off the pulley the axle had to be stopped to (safely) get that machine on-line again. Electricity de-centralized this power system. Instead of one big engine powering everything, small motors powered individual tools. The need for all the belts and axles was eliminated. Machines could be run and repaired independently. Machines could be stopped and started with a cheap switch, not an expensive clutch. Also, electric lighting was safer and brighter than gas. IIRC fires were serious problems in plants that produced lint or dust because of the explosion hazard.
Is it safe to use 3 heavy duty extension cords together?
Yes, the use of an extension cord is safe, as they have been underwriter laboratory tested. An extension cord is meant to be used as a means of bringing power to a portable device for a temporary period of time. They should only to be used as a temporary fix until a permanent installation can be installed.
The block diagram of a star delta starter?
The Star/Delta starter is probably the most commonly used reduced voltage starter, but in a large number of applications, the performance achieved is less than ideal, and in some cases, the damage and interference is much worse than that caused by a Direct On Line starter.
The Star/Delta starter requires a six terminal motor that is delta connected at the supply voltage. The Star Delta starter employs three contactors to initially start the motor in a star connection, then after a period of time, to reconnect the motor to the supply in a delta connection. While in the star connection, the voltage across each winding is reduced by a factor of (1 /.'/'3) [1 divided by root three]. This results in a start-current reduction to (1 /.'/'3) [1 divided by root three] of the DOL start current and a start torque reduction to one third of the DOL start torque.
If there is insufficient torque available while connected in star, the motor can only accelerate to a partial speed compared to the full speed it would reach if connected in delta. When the timer operates (set normally from 5-10 seconds), the motor is disconnected from the supply and then reconnected in delta, resulting in full line voltage running currents and torque.
The transition from star connection to delta connection requires that the current flow through the motor is interrupted. This is termed "Open Transition Switching" and with an induction motor operating at a partial speed compared to full load speed, there is a large current and torque transient produced at the poi, unless proper protection methods are used, can cause severe damage to the supply service's infrastructire and to other connected equipment.
If there is insufficient torque produced by the motor when running in star, there is no way to accelerate the load to full speed without switching to delta and causing those severe current and torque transients. These must be allowed-for in the design of the motor and its starting system if they are to have an economic useful life.
Update: Electronic motor-control systems, which offer soft-starts in DELTA configuration, are now replacing the use of manual or semi-automatic star-delta starters.
Technical explanation
When the windings of a 3-phase motor are connected in STAR:
- the voltage applied to each winding is reduced to only (1 /.'/'3) [1 divided by root three] of the voltage applied to the winding when it is connected directly across two incoming power service lines in DELTA.
- the current per winding is reduced to only (1 /.'/'3) [1 divided by root three] of the normal running current taken when it is connected in DELTA.
- so, because of the Power Law V [in volts] x I [in amps] = P [in watts],
the total output power when the motor is connected in STAR is:
PS = [VL x (1/.'/'3)] x [ID x (1/.'/'3)] = PD x (1/3) [one third of the power in DELTA]
where:
VL is the line-to-line voltage of the incoming 3-phase power service
ID is the line current drawn in DELTA
PS is the total power the motor can produce when running in STAR
PD is the total power it can produce when running in DELTA.
- a further disadvantage when the motor is connected in STAR is that its total output torque is only 1/3 of the total torque it can produce when running in DELTA.
For more information please see the answers to the Related Questions shown below.
The voltage phase shift between primary and secondary connections in a transformer is 180 electrical degrees.
How is a 380v 3-phase machine to a 208v simple phase outlet possible?
if you wound 3-phase on primary of transformer and secondary side we have to only one cable only such a way that it works as a step down transformer.
AnswerYou cannot run a three-phase machine directly from a single-phase (which is what I assume you mean) supply. It won't start. The voltage difference is irrelevant.
What is fundamental of phase rotation in 3phase system?
The fundamental is defined as the primary frequency of the system. In other words the fundamental of a 60 hz system is 60 hertz x 1 = 60 hz In discussions involving harmonics is is common to see terms such as the 3rd harmonic. This means that it is a frequency that is 3x the fundamental or 180 hz.
What is the purpose of line trap?
A line trap is a set of physically-large inductors often seen hanging from transmission towers at the end of a high-voltage transmission line, where the line terminates at a substation. As transmission lines often carry data signals, which operate at frequencies very much higher than the 50-Hz (or 60-Hz) power frequency, the high inductive reactance* of the line traps act to prevent these signals from continuing beyond the end of that section of transmission line, while having an insignificant effect on the power-frequency load current.
(*Inductive reactance is directly proportional to frequency)
A BX connector is a special type of box connector used for securing a BX cable to a junction box. BX is a type of armoured cable that is used for specific locations where ordinary Romex cable could become damaged. Before the connector is installed onto the BX cable there is a small PVC collar to be installed. In the trade it is called an anti short. It slides between the outer sheath of the BX and the conductors inside the sheath. It adds protection for the inner conductors from rubbing against the outer sheath if any vibration is involved in the installation. There is usually a small hole in the BX connector and the red anti short can be seen through this hole. This makes it easy for the electrical inspector to see if the anti short bushing has been installed during an inspection, and they do check.
When finding fault in NEXT and FEXT the problem is usually too many twists in the cable although with NEXT the problem is at the same end of the cable that generated the signal whereas with FEXT the problem occurs at the opposite end of the cable where the signal was sent.
What is the cable size for 55 kva genset with cable length of 56 meters?
To answer this question the voltage of the genset is needed.
Automatic Switch Interface (ASI)
The CAIRS OSS ASI module is a multiple switching platform provisioning tool that increases the power and accuracy of the CAIRS system substantially. Working in either a single or multiple switch environment, the ASI module is a cross platform scripting language that can communicate to any switch that utilizes ASCII, Binary, XML file configuration commands (i.e. Nortel, Avaya, Lucent, Siemens & Redcom). Although the ASI module carries the complexities of a programming language, all of the hard work is done behind the scenes. When CAIRS users open a work order that requires a switch assignment, CAIRS writes a change request to the ASI sub-folder in the CAIRS database. Watching the CAIRS database real time for new work orders requests, the ASI module interprets each new work order to determine the assignment type. Once the ASI module has successfully programmed the switch it returns an assignment summary to the CAIRS users. The assignment summary notifies the CAIRS user that the assignment has been completed successfully.
Can you fit a BNC connector to a Shielded twisted pair cable?
Control Panel is virtually the control center of your computer. It allows you to change settings for programs, hardware devices, set up network connections and user accounts. Basically its customizing your computer.
If you're working on a school or office computer which is linked to the network, they probably won't let you change your settings since you could somehow cause damage to the system or change their desired settings.
