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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 difference between earthing boss and earthing lug and where to use?
An earthing boss and earthing lug are parts of a grounding connection. An earthing boss is in a casting that allows for the drilling and tapping of hole. A earthing lug is used to bond a wire to the ground.
How do you test motor thermal protection relay?
The thermistor motor protection relays CM-MSE, CM-MSS and CM-MSN are used to control motors equipped with PTC temperature sensors. The PTC temperature sensors are incorporated in the motor windings to measure the motor heating. This enables direct control and evaluation of various operating conditions. Depending on the products also ATEX approvals for use in hazardous areas are available.
In electrical circuits what wire protects the operator?
Earth wire is meant to protect the user in case there is earth fault in the device or circuit. Only earth wire alone is not sufficient. It needs to be provided with suitable circuit breaker that breaks the circuit automatically.
Hair dryers usually have a HIGH and a LOW setting. The HIGH heating element is about 8 ohms. The LOW heating element is about 32 ohms. voltage (squared) / resistance = power (watts) 120*120 / 8 = 1800 watts ( HIGH ) 120*120 / 32 = 450 watts ( LOW ) When the voltage switch is set to 240 volts, ALL it does is limit the HIGH/LOW switch to the LOW setting. 240*240 / 32 = 1800 watts ( LOW ) 240*240 / 8 = 7200 watts ( HIGH ) (the heating element would burn out)
How do you locate the neutral brush position in a dc motor?
leave the brushes of the motor at the position where the induced voltage is zero
Why DC supply is used in control circuit?
dc supply is used for control circuit because dc current is an independent source .
What is the relation between Newton meter and watt?
1 Watt = 1 Joule / Second = 1 Newton-meter / Second.
True
2 amps. If it is D.C.
Why is a synchronous speed motor considered a constant speed motor?
synchronous motor is a constant speed motor because it will only run at a synchronous speed or not at all.the speed can be changed by changiing the frequency only ns=120f/p
How do you calculate rating of 11 kv transformer?
The KVA rating of a transformer is based on how much heat the transformer can dissipate. The BIL rating is based on how well the windings are insulated. There are other "ratings" as well. Rough calculations can be done, but tests are generally performed to prove the calculations (transformer designers will design on the conservative side to insure the transformer meets specification). These type of calculations are best done by a computer. You will struggle to determine the hot spot max temperature rise in a transformer by hand.
If you connect two identical AC to DC converters together in series does the output amperage change?
Wiring the DC outputs of the 2 converters in series would double the DC output voltage but not the current (amperage). The maximum safe output current would just be the same as the rating of the convertor which has been designed for the least current output. So be sure to check the rating plates of the two convertors to see which one has the lowest output current: that is the maximum current your load device should take. Yes you can do them in series. You take the positive of one and connect it to the negative of the other, then the other positive and negative are still pos. and neg.,,,,,,,,,,,,,,, This will double the VOLTAGE but keep the AMPERAGE the same. ,,,,,,,,,,,,,,, I do not know if it will actually work or not on A transformer though. For parallel : You connect the pos. to pos. and neg. to neg., This will keep the VOLTAGE the same, and double the AMPERAGE.,,,,,,,,,,,,,,,, I don't know if this will work or not either. This will work on BATTERIES, I am not sure about transformers. Re the parallel case mentioned above, that is a very well-worded answer because it is cautious about saying what is likely to happen! To illustrate that case: you have a 12 volt DC car light bulb which is rated at 60 Watts so it takes a current of 5 Amps. You want to power-up the bulb from the mains using two AC to DC converters which each have a 12 volt DC output voltage but a rated output current of only 2.5 Amps each. Wiring the DC outputs in parallel could work to allow double the current output of a single converter to be produced BUT ONLY IF THE TWO CONVERTERS WERE CAREFULLY WIRED with their DC + terminals (or wires) connected together and their DC - terminals (or wires) connected together. *** (See note below.) However, whilst the resulting output voltage might be close to the output voltage of one of the converters, that cannot just be assumed! Particularly if the converters were not identical (if they were of different makes and/or power outputs, say) then the different slew rates of the convertors could cause the final output voltage to hunt around as the two converters tried to control each other. This voltage hunting would be accompanied (or caused by!) a current circulating between the two converters that was much higher than they were designed to handle. If they were badly matched such an unstable situation could lead to serious overheating and maybe a burnout of one of the convertors, if not both, even if there was no actual visible smoke and/or fire. (However this is not likely to be as bad as the situation described in the Note *** below.) Such voltage hunting and higher than normal output current circulating between the converters (please note this does not involve the attached load - say a light bulb - at all!) might not be visible using normal test meters but, if present, would be seen on an oscilloscope. To be safe - and to help avoid any overheating or burning-out of one or both of the converters - if you wished to try using them in parallel it would be very wise to wire a proper lab-type variometer into the AC mains feed and, whilst everything is switched off, attach your desired load to the parallel-connected outputs of the two AC to DC converters. Then do this test: very slowly bring up the AC supply voltage from zero, measuring both the DC output current and voltage of each converter all the time. You should also watch and feel the adapters throughout the test to be able to detect any signs of overheating well before the full mains voltage is tried. If you don't have the right kinds of controllers and instruments to measure what is really happening it would be best not even to try to do the above parallel-connecting "blind" at all. ("Blind" meaning "without instruments".) Instead the best plan would be to obtain a single AC to DC converter which has been designed to give the desired output current at the desired voltage. *** Note : IF THE CONVERTERS WERE WRONGLY WIRED with the DC + terminals (or wires) of one connected to the DC - terminals (or wires) of the other THERE WOULD BE A MASSIVE CURRENT CIRCULATING BETWEEN THE TWO CONVERTORS AND, IF FULL MAINS VOLTAGE WERE SUPPLIED, BURNOUT IS PRETTY MUCH GUARANTEED!
Difference between voltage and current?
Voltage is electrical potential, measure in derived units of volts, which is joules per coulomb. Current is electrical flow, measured in derived units of amperes, which is coulombs per second. Stated in other terms, voltage is energy per charge, while current is charge per time. That makes power, or watts, equal to energy per time, and that is joules per second.
If you think of the water system analogy, volts is sort of similar to pounds per square inch (though not completely so), while amperes is similar to gallons per minute.
AnswerVoltage is synonymous with 'potential difference' -not potential- measured in volts. Current is the flow of electrical charge, measured in amperes. The volt is an SI derived unit, wheras an ampere is an SI base unit.
How do you make a electrical earth pit?
EARTH PIT CONSTRUCTION AS PER INDIAN ELECTRICITY BOARD
1. Excavation on earth for a normal earth Pit size is 1.5M X 1.5M X 3.0 M
2. Use 500 mm X 500 mm X 10 mm GI Plate (Plate may be use as big as possible to contact more and more area of Earth for low resistance & best result)
3. Make a mixture of Wood Coal Powder Salt & Sand all in equal part
(a) Wood Coal Powder use as good conductor of electricity, anti corrosive, rust prove for GI Plate for long life.
(b) Salt use as electrolyte to form conductivity between GI Plate Coal and Earth with humidity
(c) Sand has used to form porosity to cycle water & humidity around the mixture
4. Put GI Plate (EARTH PLATE) of size 500 mm X 500 mm X 10 mm in the mid of mixture
5. Use Double GI Strip size 30 mm X 10 mm to connect GI Plate to System Earthling
6. It will be better to use GI Pipe of size 2.5" diameter with a Flange on the top of GI Pipe to cover GI Strip from EARTH PLATE to Top Flange
7. Cover Top of GI pipe with a T joint to avoid jamming of pipe with dust & mud and also use water time to time through this pipe to bottom of earth plate
8. Maintain less than one Ohm Resistance from EARTH PIT conductor to a distance of 15 Meters around the EARTH PIT with an other conductor dip on the Earth at least 500 mm deep.
9. Check Voltage between EARTH PIT conductor to Neutral of Mains Supply 220V AC 50 Hz it should be less than 2.0 Volts
Low current will equal low power losses due to the resistance of the cable. I squared R. (I is transmission current and R is resistance/Metre of cable) by increasing the voltage for the same amount of power the current decreases. Power transmission will take that advantage to transfer less current for the same amount of power.
What is the effect of capacitance in high frequency circuits and how it is getting added?
First, capacitance is the resistance of something to a change in voltage. And capacitance exists anywhere there is a conductor that is insulated from another conductor. With that definition, anything has capacitance. And that's correct. It is also the key to understanding the capacitance in high frequency (radio frequency or RF) circuits. The fact that a circuit had conductive pathways and component leads and such means that there is a lot of little bits of capacitance distributed around the circuit. The capacitance is already there; it isn't "added" later as might be inferred. Normally, this bit of capacitance isn't a problem. But at higher and higher frequencies, it is. Remember that the higher the frequency of an AC signal, the better it goes through a given cap. So at higher and higher frequencies, the distributed capacitance in the circuit "shorts the signal to ground" and takes it out of the circuit. The RF is said to be coupled out of the circuit through the distributed capacitance in that circuit. The higher the frequency a given circuit is asked to deal with, the more signal will be lost to this effect. It's just that simple. Design considerations and proper component selection minimize the distributed capacitance in a circuit.
Why synchronous motor called double excited motor?
AC and DC supply sources we are given to motor so we are called double excited motor
If a 9volt battery produces a current of 3amps through a load the resistance of the load is?
3 ohms. 9 volts across a 3 ohm resistor becomes 9/3 or 3 amps.
Depending on the load of your lighting circuit. I would measure the current with an inductive amp meter. once you know the current required for your lighting circuit, you then install a circuit breaker which is 15% higher than your load. eg, load is 10A. 10A load + 15 % = 12A breaker (15 A is ok as the breaker is used to protect the wiring and should be rated in consequence of your wiring by 25% less or its current rating, or less, not the load)
The humming of your lighting circuit breaker indicates that your breaker is either faulty, or having a difficult time keeping a closed circuit. Or simply that the manufacturer produced a breaker that hums by nature of its construction.
What is difference between generator and oscillator?
A generator is used to convert mechanical energy to electrical energy.
An oscillator is used to convert dc to ac
What is the voltage in 5 amps?
Voltage is a measurement of electrical force and amperage is a measurement of electrical flow.
They are two different things altogether.
What is maximum voltage produced in thermocouple?
A:The best platinum thermocouple can give upto 64mv
Which circuits are used in houses?
110 and 220 volt AC supply wiring for the house lights and appliance, heating and air operations. Also computer connection wiring, cable tv lines, phones lines, intercom lines, burglar alarm circuits, property TV monitors, Lawn watering controls, door bell circuits, heating and air control lines. Dont forget to add a lightning arrestor on the roof and a large copper cable to a ground system. JH
