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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
Why are you getting voltage between one phase and another phase on a 3 phase system. should it be 0?
You are asking why, if each line voltage to neutral is nearly identical (on a voltmeter), how there is a large voltage between lines?
The answer has to do with phase angle and how the voltages, on each line, are rapidly changing sinusoidal wave-forms. The voltages are rhythmically out of step on purpose.
Imagine three fast drummers that take turns making a single beat one after another with their left hands, yet maintaining a counter beat with their right hands. Or better yet, imagine three pistons on a crank-shaft pushing and pulling sequentially. They are not in step, and never in the same positions&direction at the same time.
What Nicolas Tesla invented allows three lines to carry 73% more power than a pair of lines! WOW!
What happems when frequency is changed and voltage and current remain unchanged?
In magnetic circuits, such as occur in transformers and motors, the flux density is inversely proportional to the frequency, so a drop in frequency could cause overheating through excessive flux density.
Answer
An ampere (symbol: A) is the base unit of current in the SI system, and is defined in terms of the force between two, parallel, current-carrying conductors, due to the interaction of their magnetic fields.
It's defined as follows: 'that constant current that, if maintained in two straight parallel conductors of infinite length and negligible cross-sectional area and placed one metre apart in a vacuum, would produce between them a force equal to 2 �� 10-7 newtons per unit length'.
What is a motor drive telescope?
It is a telescope on an equatorial drive (one axis parallel to the Earth's axis). An electric motor drives the other axis at 15 degrees per hour to follow an object as it moves across the sky.
Why is it easy to charge a non conductor although it is with the hands?
It is easier to charge no-conductors with the hands because the charge generated will not be discharged through our bodies.
In AC systems, "Power Factor" is the ratio of volt-amps to watts. To get volt-amps, you also multiply volts times amps. With a resistive load, such as an incandescent lamp, volts times amps equals watts. All of the power gets dissipated heating up the lamp filament to make it glow. In this case, volt-amps is equal to watts, giving a ratio of 1:1, or 100%. With inductive loads like transformers, electric motors, fluorescent lamps, etc., there is very little resistance. Something called "reactance" limits current flow. Larger currents flow with little power being dissipated. With a power factor of 50%, double the current would flow. For example, a 40 watt incandescent lamp draws 0.33 amps. (40 watts / 120 volts = 0.33 amps) This bulb, being a resistive load, has a power factor of 100%. A single tube fluorescent lamp rated at 40 watts may draw double the current of the 40 watt incandescent, but still only use 40 watts of real power. This fixture has a power factor of 50%.
Additional Input from Contributors:- Power Factor, simply put is a % of how efficiently the AC power is being used.
THIS DOESN'T MATTER IN HOUSEHOLD ELECTRICITY. If a factory has a Power Factor of 95%, then it will draw 105% of the current it would draw if it were at 100%, or a Powerfactor of 1 (also called unity).The electric companies charge large industrial customers more for inefficient systems, i.e. Power Factor lower or higher than 1 (100% efficient). They do not charge individual homes for this, so you can't save money by correcting your power factor.
- It's a ratio of AC volt-amperes to AC watts
- Electrical meters for homes measure only resistive (real, apparent, or actual) power. They do not measure reactive power.
- In a study of alternating current (that which supplies our homes and businesses in the United States), it will be observed that there are alternating waves of both voltage and current. In a circuit with purely resistance load, the waves of current and voltage are in exact phase relationship to each other. This means that when the voltage is at its peak, the current flow is at its peak as well. An inductive load (that is, a coil) causes the current wave to lag or fall behind the voltage wave, so that the peak current flow is some time after the voltage wave is at its peak level. A capacitive load (that is, a capacitor) causes the current wave to lead or advance ahead of the voltage wave, so that the peak current flow is some time in advance of the peak of the voltage wave.The consequence of this is that the AVAILABLE REAL POWER is the relationship between the current and voltage waves.
- Resistive circuits have a power factor of 1.0, or unity, because the waves are in phase. The more out of phase the relationship between voltage and current, the less efficient the use of available power, the more "waste" energy.The less efficient the use of energy, the larger the size of transmission and generating equipment required to provide for energy needs and the more costly the operation of utilization equipment.
- Power Factor is the relationship between Current and Voltage in an electrical supply With a power factor of 1 power equals Volts multiplied by Amps (I=VxA)
Also see the related Question WHAT IS REACTIVE POWER? by clicking on the link below:
What is meant by low reluctance in transformer?
In a transformer, or on general, if a material is easily magnetized it has low reluctance.
What is the difference between the emf of a battery and the lost volts when discharging called?
Internal resistance
Can you use molded breakers instead shunt trip breakers for an Ansul fire suppression system?
Moulded breakers or shunt trip breakers - selection is defined by the current rating requirement.
How many years does the electrical engineering course take?
WHAT I UNDERSTAND WITH "DEGREE" YOU ARE ASKING IS BACCHALAUREATE DEGREE. IN MY COUNTRY - PHILIPPINES IT WILL TAKE YOU FIVE (5) YEARS. THEN YOU HAVE TO TAKE AND PASS THE GOVERNMENT BOARD EXAMINATION TO REMOVE "ING" AND BE A CERTIFIED / REGISTERED ELECTRICAL ENGINEER.
What does marreted mean regarding wiring as in - These wires are not marreted together?
A Marr connector is a brand name for a wire nut. They were one of the first companies to make a wire connector and the name in the trade has stuck. When joining wires together it is still referred to marretting the wires together. I prefer B-Caps as more wires can be gathered together. Marretts were made in three sizes 31's, 33'sand 35's. Depending on the size of the wires to be joined together will govern the size of the wire nut.
There is a great article on related links below that gives a bit of history as to how they became into being.
What is the meaning of 'lock and load'?
The term "lock and load" was used in the military during World War Two. It is a command to prepare a weapon for battle, and was popularized by John Wayne.
Which factors affect performance of magneto?
A magneto is an electric generator that is powered by magnets. Some factors that will affect its performance include their power source as well as the reliability.
What did means by the stray losses in induction motors or transformer or generator?
Stray losses refer to secondary voltage to be inappropriately distributed to transformers, induction motors and generators. Stray losses essentially mean that there is leakage that causes a weakening of the voltage being delivered to the motor.
What is the size of XL PE cable for 380 Volts in 125 KW motor?
If it's a 380 v 3-phase supply, the current is up to 300 amps which could be supplied over a short distance by XLPE cable with 70 sq. mm cross-section conductors.
What is the formula for calculating the full current load of a 400 watt metal halide light?
For the amperage of a metal halide fixture look for the nameplate which can be found on the side of the ballast. There it will tell you what the amperage of the fixture draws. Knowing what one fixture draws will allow you to size the lighting circuit for wire and breaker sizes.
Why power generated with under frequency is harmful to the load?
Why power generated with under frequency is harmful to the load?
Read more: Why_power_generated_with_under_frequency_is_harmful_to_the_load
What size armoured copper cable needed for 75 kW motor?
Wire sizing is based on the motors full load amperage. The amperage can be calculated but a voltage has to be stated. I = W/E. Amps = Watts/Volts. Restate the question with a voltage and an answer can be given.
How do you repair main circuit breaker on ships?
Repairing circuit breakers is not advisable. When a breaker is taken apart there are many parts that have to specifically align up with each other. Any misalignment and the breaker may not operate correctly if subjected to a fault condition. Do like the landlubbers do and replace the faulty breaker with a new one. This makes everyone safe.
What makes a electric motor get very hot and shutoff after 20 seconds?
what makes a electric motor get very hot and then shutoff after 20 seconds
How do you wire a single phase 480 volt starter with a photo cell for lights?
You will not be able to use the line voltage to operate the photocell directly as the photo cell is usually rated for 120 volts or in some instances 240 volts. You will need a step down transformer 480 to 120 volts. The starter will also need to have a 120 volt coil. The black and white wire of the photo cell connects to the output of the transformer and the red wire from the photocell goes to the starter coil. From the neutral terminal of the transformer a wire is taken to the other terminal on the starter coil. The transformer should be about 50 VA.
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.
Before you do any work yourself,
on electrical circuits, equipment or appliances
always use a test meter to ensure 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.
What is the difference between a single phase and a three phase inverter?
The Single and Three phase refer to Alternating Current electrical power supply outlet system and the corresponding equipment requirements.
The single phase system is generally used thepower requirements are low or moderate as for household applications , while the Three phase supply system is used for High power industrial applications.
Thenumbers of phases refer to Alternating Current Supply lines which are delivering the power or the sytem requirement of the equipment for operation.
Thus a single phase supply cannot operate a three phase equipment or vice versa.
However a ThreePhase supply can be used individually as Three different Single Phase supply systems
In case of Three Phase systems the electrical supply waveforms are such that at any given instant there is a 120 degree phase difference between any two supply lines , which also results in higher magnitude of supply voltage than the corresponding single phase supply.
Now refering to the inverter which is nothing but a device to convert the electrical
supply from one source or magnitude ( typically DC from a Battery Bank ) to the required form and Magnitude. Thus it simply generates the equivalent electrical supply either as Singleor Three Phase , which ideally will be the same as available
available from the wall outlet
What is the frequency of the secondary of a 230 volt step down transformer?
The frequency is dependant upon what electrical grid that you are connecting the transformerto. If you are connected to a 50 Hz grid, the transformer will output a voltage at 50 Hz. The same thing with the 60 Hz grid, the transformer will output a voltage at 60 Hz.
Is one volt enouph pressure for 1 ohm of resistance?
one volt applied across one ohm of resistance causes a current flow of one
