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Electrical Engineering
Electrical engineering is a field of engineering that deals with the study and application of electricity, electronics and electromagnetism.
23,056 Questions
What is the starter size Amps for 45KW 3Phase AC Motor connected to the pump?
160 Amp. MCCB 45 KW Contactor (67.5-112.5) Thermal Over Load
Open Transition Switching in star delta starter?
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 partial speed (or full load speed), there is a large current and torque transient produced at the point of reconnection. This transient is far worse than any produced by the DOL starter and can cause severe damage to equipment and the supply.
What is the difference between a Shockley diode and a Shottky diode?
A Shockley diode is a primitive diode identical to a thyristor with it's gate left disconnected.
A Schottky diode is similar to a normal avalanche diode except that it's forward voltage is quite low, and it's switching speed is very high.
Advantage of current limiting?
Current limiting is the practice in electrical or electronic circuits of imposing an upper limit on the current. The simplest form of current limiting in mains is fuse.
In vacuum tube devices, one electrode of the tube (the filament) needs low
voltage at relatively high current, while another one (the plate) needs a high
voltage at relatively low current. It's hard to build a single power supply to
provide both of these, so the filament is usually supplied from its own
separate transformer.
Nobody has worried about things like this since a short time after transistors
came along.
You need to use two formulas - firstly a= propagation delay/transmission time. We'll denote this by tprop and ttrans.
ttrans is Distance/Data Rate
so ttrans = L / 4 x 103
ttrans = 80/L
(becasue the powers of ten cancel each other out so you just multiply 20 x 4.
we use powers of ten because we need the same format as the propogation delay
a = 80/L
2. Use the formula 1/1+2a >= .5 = 1/1+ 160/L>=.5
First 1>= .5(1+160/L)
second 1>= .5 + 80/L
third 80/L >= 1 x .5
fourth .5 >= 80/L
L >= 80/.5
L >= 160
How much power is needed for an antenna to send a signal?
I'm not an electronic whiz by ANY means, but if I'm correct...Transmitters do the sending and antennas do the receiving.
They refer to the number of I/O lines (not power) needed to transfer data between to processors/controllers.
3 wire serial has a bidirectional data line, a clock line, and a master/slave line.
2 wire generally is clock and data.
What is electric potential difference?
Potential Difference (p.d) in an electric circuit is the measurement of energy transfer per unit charge in volts (v) or joules per coulomb (JC^-1). However, in contrast to the Electromotive Force (emf) in a circuit, which is a component that adds charge to the current (usually a cell). p.d uses up the charge to power a component eg a lamp. We would express this as the potential difference across the lamp. We can also say pd (v) = workdone (W)/ charge (Q). because the transfer of energy is the work done and this is per unit of charge.
Example.
What is the pd through a lamp where we have 4 coulombs of charge passing through it and transferring 48 joules of electrical energy into heat and light.
V=W/Q
pd=48/4 =12v
A device, composed of sharp points and/or knife edges, that discharges powerline overvoltages to ground. The term lightning arrestor is a misnomer, as these devices cannot protect against a direct strike to the powerline!
What is the Limit switches working principle?
Limit switch is one type Of " Contact Sensor" , In that there is Normally Open Contact & Normally Close Contact, In limit switch there is Plunger it is Directly Connected to NO & NC Contact if we press the plunger NO contact become NC & NC contact become NO, Working Principle same as Contactor ( DOL starter ) main difference is in contactor There is Coil to attract the Plunger But In Limit Swict Plunger is Operated Mecanically.Limit Switches is used mainly for Safety Purpose & to take Feed back for PLC in Automation industries........
Source(s):In My Plant I have installed limit Switches..A limit switch is a switch, usually mechanical, that is actuated by a moving part of some machine. Its operation is much like any other switch in that there are contacts that move when a plunger or lever on the outside of the switch is pushed. Internally there is an over center spring mechanism that snaps the switch open or shut in response to a gradual motion of the plunger or lever.
Many limit switches have three terminals. One is the normally closed contact, another the normally open contact, and the third is the common that switches between these two as the mechanism is moved.
This is what the value would be on a rating system. There are several different values that can be assigned and they help to determine how well the product is working.
How do you measure electrical current?
Electric current is measured using an instrument called an ammeter. The SI unit of measurement for current is the ampere, which is defined in terms of the force between parallel, current-carrying, conductors due to the interaction of their magnetic fields.
Drawings with specifications are available on the web from BVR Electrical Systems. A link is provided. (Scroll down.)
What does a negative value for a reactive power means?
Meaning it's a capacitive load. Leading power factor
What is external critical resistance of shunt generator?
it is the resistance with which the generatoe just excite.
a unit defined in terms of units of fundamental quantities
How are electric wires manufactured?
Electric wires are manufactured in various ways. One of the most common methods is the strip twist where wires are enhanced to hold mechanical loads.Ê
How do you discharge 25 Kvar capacitor in 690Volt system?
This capacitor carries a current of 25,000/690 or 36.2 amps and its impedance (reactance) is 19 ohms. The capacitance is 1/(2.pi.50.19) or 0.000167 Farad, on a 50 Hz system.
The time-constant is CR so that if a 20,000 ohm resistor is placed across the capacitor the time-constant is 3.3 seconds. The voltage is reduced by 99% after 5 time-constants or in this case 17 seconds.
If the discharge resistor is permanently in circuit it dissipates 690^2 / 20000 or 24 watts.
What is the principal of DC Generator?
BASIC PRINCIPLE OF OPERATION
The generator is an application of electromagnetic induction. It works on theprinciple that when a wire is moved in a magnetic field, then the current isinduced in the coil. A rectangular coil is made to rotate rapidly in the magneticfield between the poles of a horse shoe type magnet. When the coil rotates, it cutsthe lines of magnetic force, due to which a current is produced in the generatorcoil. This current can be used to run the various electrical appliances
Air conditioner is a resistive or a reactive load. Please explain.?
Its actually inductive, because the energy being used is to turn motors. Motor are an inductive load, so the end load is reactive. Do your own research so you will know how to apply it someday.
Orchestra conductors are important because they keep all the musician in sync and on time with each other.
If you're referring to conductors of electricity, they're important because they let electricity flow.
What is Total Harmonic Distortion of a Diesel Generator?
Total harmonic distortion is a measurement of harmonic distortion in an object and is the percentageÊof the powers of all the harmonic components of the object. The THD of a diesel generator is between 15% and 20%.
