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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
Can you use a 60Hz transformer in a 400Hz low power system?
There's no problem except that the transformer will be more massive than necessary. It will work at the same voltage and current, but there is less iron loss, so the voltage rating can be increased by a maximum of 15-20% and the current rating can be increased by 15-20% also.
But if this is in an aircraft or other safety-critical application, do not overrate the transformer.
When your ripple is a lot lower than the supply voltage, here is a rule of thumb:
for a single diode rectifier: U = I/(100*C) with I in ampere, C in uF
for example 1A supply, 1000 uF cap, gives Upp = 1/100e-3= 10 Volts.
Use 60 for 60 Hz line systems.
for a bridge diode retifier: U = I/(50*C) with I in ampere, C in uF
for example 1A supply, 1000 uF cap, gives Upp = 1/50e-3= 5 Volts peak to peak.
Use 120 for 60 Hz line systems.
Note: it is only an approximation, does not include resistances etc.
What is the effect of induction motor on power factor?
An induction motor has a lagging power factor. Motors of more than about 2 HP are designed to have a power factor of 0.85 or higher.
When does the armature of dc motor gets over heated?
a properly designed motor wont overheat unless it is overloaded
this is something like 3/4" drill with a 1/4" shaft that is used to drill in steel
sometimes hole saws have a 1/4" mandrel that will hold the entire line of saws
the motor must be matched to the load
It's when a failure of one circuit leads to another circuit to fail. This can be intentional,for protection purpose, or it may not be intentional. Cascade tripping is common in sequenced circuit.
Why electromagnets over permanent magnets for a large dc machine?
The flux density of an electromagnet can be easily controlled. It's also easy and cheap to produce a large flux density with an electromagnet which is necessary for such large dc motors. Permanent magnets are generally expensive. For such a large motor,a very large permanent magnet will be needed for that motor which will not be ideal.
AnswerElectromagnets are more powerful than temporary magnets, and -as pointed out above- their flux density can be controlled.
What is the formula to convert 440 to 220 single phase while in motor rewinding?
If it was 440 v single-phase, use half the number of turns in the windings, but use thicker wire of double the cross-section. Or to use the same wire again, fold the wire once into half its length and use that.
To answer this question, i need the power factor of the motor.
CommentYou don't need the power factor, as you already know its true power (watts), but you do need to know the efficiency of the motor to determine its input power. You also need to know the cost per kilowatt hour.
But you can get a rough idea by multiplying the number of kilowatts, by the time in hours, by the cost per kilowatt hour. For a more accurate answer, you need to divide this by the efficiency of the motor.
Why direction is clock wise of 3 phase induction machine?
It depends which side of the motor you are looking at!
Why capacitor used in a DC inverter?
capacitor is component used to store and release the electric charge.and also it has feature to block the dc but bypass ac.and inverter is device which converts ac to dc and then again ac
What is the equivalent of AMPS to horse power?
You are thinking watts to horsepower, not amps to horsepower. Please restate the question.
What is relation between speed of generator?
Between speed and what. Please restate the question. There is insufficient information in the question to answer it.
Why the speed decreases when the poles increases in a motor?
because N=(120*f)/P where N= speed in rpm f= frequency in Hz P= no. of poles as the relations shows above it is cleare that speed of machine inversly proportional to no. of poles.. so as the poles increses, speed of the machine decreses
What is an instrument transformer?
An 'instrument transformer' is a category of transformer used to supply measuring instruments or protective relays. There are two types of instrument transformer: a 'voltage transformer' (known as 'potential transformer' in North America), and a 'current transformer'. They are used with high-voltage systems, where it is hazardous to connect instruments directly to such systems.
Voltage tranformers are used to reduce high-voltages down to a level that can be safely applied to voltmeters, or to the voltage-coils of wattmeters or energy meters, or to protective relays, while electrically-isolating those instruments (and personnel) from the high-voltage supply.
Current tranformersare used to reduce high-voltage currents down to a level that can be safely applied to ammeters, or to the current-coils of wattmeters or energy meters, or to protective relays, while electrically-isolating those instrument (and personnel) from the high-voltage supply.
What is KNAN transformer cooling?
Each letter in KNAN transformer cooling stands for something different. K indicates a beyond 300-degree Celsius flash point, N denotes natural, and A is equal to air.
WHAT will happen if you run oil transformer with out oil?
As well as providing a cooling medium, transformer oil is also used to insulate a transformer. As its dielectric strength (how well it insulates) is much higher than air, it means that components within a transformer that are at different potentials can be placed much closer together if they are immersed in oil. So, operating an oil-filled transformer without oil will likely cause insulation breakdown within the transformer.
Is Sodium Hexa Fluoride Gas used in electrical circuit breakers?
yes SF6 gas is used in modern ckt. breaker.
Ohm's Law states that 'the current flowing through a conductor, at constant temperature, is directly proportional to the potential difference across that conductor'.
The ratio of voltage (U) to current (I) is called the resistance (R) of the circuit:
U/I = R
While the above equation will always determine the resistance of a circuit, Ohm's Law itself only applies to those circuits whose ratio of voltage to current remains constant over a range of voltages.
A protective relay is a device designed to trip a circuit breaker when a fault is detected. The first protective relays were electromagnetic devices, relying on coils operating on moving parts to provide detection of abnormal operating conditions such as over-current, over-voltage, reverse power flow, over- and under- frequency. Microprocessor-based digital protection relays now emulate the original devices, as well as providing types of protection and supervision impractical with electromechanical relays. In many cases a single microprocessor relay provides functions that would take two or more electromechanical devices. By combining several functions in one case, numerical relays also save capital cost and maintenance cost over electromechanical relays. However, due to their very long life span, tens of thousands of these "silent sentinels" are still protecting transmission lines and electrical apparatus all over the world. An important transmission line or generator unit will have cubicles dedicated to protection, with many individual electromechanical devices, or one or two microprocessor relays.
How you can convert 1-phase voltage to 3-phase voltage and vice-vars a?
A single-phase supply is obtained between any two line conductors or between a line and neutral conductor of a three-phase supply. To obtain a three-phase supply from a single-phase source is far more difficult, and requires additional equipment.
Can batteries of unequal voltages b connected in parallel?
no..... The battery with lower voltage will consume power from the higher one...
What does 35V and 1000uF on capacitor specify?
1000 microfarads is its rated capacitance, while 35 volts is its rated voltage.
How do you find the transformer block in Alien Shooter 2?
To find the transformer block in Alien Shooter 2 you have to go down the sewer. This is one of the most thrilling games.
