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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
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3 ohms
What is bus potential transformer in electrical?
Potential transformers are instrument transformers. They have a large number of primary turns and a few number of secondary turns. It is used to control the large value of voltage.
WORKING:
The potential transformer works along the same principle of other transformers. It converts voltages from high to low. It will take the thousands of volts behind power transmission systems and step the voltage down to something that meters can handle. These transformers work for single and three phase systems, and are attached at a point where it is convenient to measure the voltage.
What is the difference between parallel and cereal circuits?
in the series circuit elements are one behind the other ie +ve terminal of one element is connected to the -ve of other element of the circuit whenever in parallel circuits the elements are parallely connect ie all +ve terminal are connected at a point and all -ve terminals of the elements are connected at a point.
What are the phases of reengineering?
Developing solution is a common BPR phase that includes detailed process definition, system requirements writing and system development, training development, implementation planning, operational transition plan, pilots and trials.
The unit kWh is a unit of energy, which is power multiplied by time. Multiply the power of the equipment (measured in W or kW) by time used (measured in h) and you get the energy in kWh.
Examples:
A power of 1 kW over a time of one hour is one kWh. A 100 W (0.1 kW) bulb left on for 5 hours uses 0.1 x 5 = 0.5 kWh.
If your home uses an average of 500 W (0.5 kW) then it will consume 12 kWh per day (24 h).
Also not the correct capitalization. Only the W (watt) is capitalized, the k (kilo = 1000) prefix and the time unit h (hour) are not.
Simply, multiply power (kW) from the time (in hours) the equipment has been used..
P (kW) x t (h) = Pt (kWh)
What will happened if cells were connected in parallel connection but in opposite polarities?
You would get a high circulating current through both cells, possibly enough to do significant damage to both the cells and to you, depending on the capacity of the cells. Technically, they would actually be connected in series, not parallel!
A: A zener is a diode that when connected in the reverse mode current direction it will breakdown to a predetermined voltage any further increasing voltage the breakdown will remain practically the same.
Can you single phase 220VAC in place of three phase 220VAC?
Yes, just use L1 and L2 ( just 2 of the 3 legs), or one of the legs to a neutral wire if equipped. Just make sure the voltage is the same as the 220 volts you wish to have with single phase service.
What is single phase dc system?
Single-phase means you have a simple AC supply on two wires, usually a live and neutral, as supplied to the average house throughout the world. Single-phase also includes a split-phase system where you have for example a 240 v supply with a centre-tap neutral giving two separate 120 v supplies.
The alternative is three-phase, which can be on three wires or it can include a 4th neutral wire. It is used for transmission of power in bulk because it uses wire efficiently over long distances.
The four phases of exercise are: warm up, stretching, conditioning and cool down. These phases are important to prepare the body and for easy recovery of the body after the exercise.
How many amps does 1 phase 220volt 7.5 HP draw?
Look at the motor nameplate and it shoud have the amp draw on it. If the nameplate is missing, then the amp draw depends on what type of motor it is.
The basic calculation to get you in the ball park would be as follows:
1 HP = 0.75 KW
7.5 HP = 5.63 KW
Assume the efficiency of the motor is 80%, then the power supplied will need to be 5.63/0.8 = 7.04 KW
amp draw = 7040/220 = 32 amps
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For calculation purposes the electrical code book states that a 7.5 HP motor draws 40 amps.
How many amps does a 110 volt 1.3 kw motor draw?
110 volts divided by 1,300 watts(1.3 kw) = .09 kw or 900 watts.
How emf induce while apply in primary side of the transformer?
when an alternating current apply on primary side of transformer then magnetic flux produced in the iron core of transformer.Then flux link with secondary winding of transformer so that an emf produced in a transformer.
It increases. The time constant of a simple RC circuit is RC, resistance times capacitance. That is the length of time it will take for the capacitor voltage to reach about 63% of a delta step change. Ratio-metrically, if you double the resistance, you will double the charge or discharge time.
It depends on the losses in the inverter, the only accurate method would be to measure the voltage and current going into the inverter and calculate from there. However i'd imagine the losses from the inverter would be pretty low, so not much more than 180-200W at an estimate
Why use two wattmeter to calculate the power of a three phase load?
Two wattmeter method is used in a three phase sysstem to measure the true power without regard to the balance ie. It can be used to measure both balanced loads and unbalanced loads.
The three phase power could be measured using single phase wattmeters in each loads of the system. But using three wattmeters is quite unnecessary as we can measure it by using only two wattmeters.
The three phase power could be measued by using single phase wattmeters , haing a current coil in one line and a potential coil connected between the line and some arbitrary common junction point. If that arbitrary common point is chosen on one of the three lines, then the wattmeter connected to that line will indicate zero power because it's potential coil has no voltage across it. hence, that wattmeter may be eliminated, and the three phase power can be determined by means of only two single phase wattmeters.
10.2 kilo ohms is the resistance necessary for 1 volt to induce a current of 98.04 micro amperes. Ohm's law: voltage equals current times resistance.
The formula for this question is I=P/E
Where I = Current
P = Watts
E = Volts
Therefore applying this formula: I = 1500 / 120
= 12.5
What happens when you disconnect a neutral at source in a three phase system?
== == == == It is true. Damage will most likely result somewhere, maybe not everything. When a neutral on a multi-wire circuit is opened (open-circuited) (removed) (cut) while things are under load, the voltage will change at the loads. Some loads will get more than normal, some will get less. The damage usually occurs on the side that gets MORE voltage. For example: your TV may be on a circuit that goes from 120volts to 50 volts, while your light bulb goes from 120volts to 180volts and blows. It all depends on how "balanced" the circuit is. In theory, if the loads are perfectly balanced then the neutral is not needed. In reality loads vary constantly, therefore, the voltage will vary if the neutral is open-circuited. That means running with an open neutral is something that anyone with any smarts at all will not do. It is absolutely possible to damage equipment by opening the neutral in some circumstances. <><><>
As always, if you are in doubt about what to do, the best advice anyone should give you is to call a licensed electrician to advise what work is needed.
If you do this work yourself, always turn off the power
at the breaker box/fuse panel BEFORE you attempt to do any work AND
always use an electrician's test meter having metal-tipped probes
(not a simple proximity voltage indicator)
to insure the circuit is, in fact, de-energized.
IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOB
SAFELY AND COMPETENTLY
REFER THIS WORK TO QUALIFIED PROFESSIONALS.
Electrolytic capacitors are capacitors in which one or both of the plates is a non-metallic conductive surface, or in other words, an electrolyte. Electrolytic capacitors come in a variety of types including: aluminum electrolytic capacitor; tantalum; and a solid aluminum electrolytic capacitor with organic semiconductor electrolyte or OS-CON.
Why transformer core is laminated?
The reason we laminate the iron cores in transformers is because we want to limit what are called eddy currents. Transformers are basically two coils of wire wrapped around a core of iron. They work by induction. Induction occurs when current flows in one conductor (or one set of windings in the transformer) and the magnetic field that forms around that conductor (that set of windings) sweeps the other conductor (the other set of windings) and induces a voltage. In order to increase the effectiveness of the transformer, we need to improve the way the magnetic fields are coupled from one set of windings to the other set. Iron conducts magnetic lines of force well, so we use that to help conduct the magnetic lines of force from coil A to coil B. Problem is, iron is also a conductor, and it's being swept by the magnetic field as well. If we didn't use laminations, the iron core would provide a place for the magnetic lines to produce (induce) current, and that current flowing in the core would heat the core up really fast and waste energy. By laminating the cores, we break up the current paths within that core and limit eddy currents.
How do you avoid floating neutral?
The neutral of a generator should never get into a condition where is is floating. All generators have the neutral tied to the frame of the generator set. It comes this way from the manufacturer. If it is floating then someone has disconnected the neutral wire from the frame. Just reconnect the neutral to the generator frame again to stop it from floating. Larger generators should also have a ground rod connected to the generator frame for grounding purposes.
