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Volt-Amp gets its name from Ohm's law, where volts X amps = watts. You will commonly see it abreviated as VA. Also called apparent power. So, when we say volt-amps, we are alluding to a measurement of power. Strictly speaking, VA is not always EXACTLY the same as watts though. In a DC circuit, or an AC circuit where the load is non-reactive (purely resistive), volt-amps are exactly the same as watts. In an AC circuit where the load is reactive, current is not exactly in phase with the voltage, and watts (true power) will be lower than VA. For example, consider a standby power generator like you might buy for a building. It may be rated for 10,000 VA if it is feeding non-reactive loads, like electric heaters and incandescent lamps. BUT, the same generator may have a watt rating of only 8,500, meaning if it is powering a reactive load like motors, flourescent lamps or computers, it is limited to less than 10,000. The difference is called power-factor. In the example above, the power-factor would be 0.85. If you want to lean more (who doesnt?) do a Google search for the following terms: true power apparent power power factor reactive power KVAR (kilovolt-amp reactive)
It is a measurement of total power. Very similar to watts. Volt-Amps is also known as VA. The formula is: VA = Volts * Amps
What else can I help you with?
What is LPF?
LPF is Low power factor, which is used to calculate overall power in VA (voltamps) kind of like calculating overall power in watts.
How does increase in VAR cause increases in bearing damage caused by shaft vibration in the shaft connecting turbine to generator in a 210 MW turbine-generator set?
Another answer which was given to this question is now in the Discussion Area. It gives advice about running small domestic motor-generator sets but does not address the actual question here which is about the kind of turbine-alternator set used in a major power station capable of generating up to 210 MegaWatts of power. Because of the highly technical details given in the question it is clear that it is probably from an exam in electrical engineering and not one on electrical wiring. The full answer to this question would take a chapter in a heavy book about the design of turbine-alternator sets, the kind usually held in an engineering/technical library! Whilst the student should really use his recommended course materials, for those who may be interested this may be a possible part-answer: : VAR means "VoltAmps Reactive". : In the ideal world there would only be purely resistive loads so that there would be no large currents out of phase with the generated voltage taken by loads having high power factors. : Such out of phase currents can easily lead to shaft vibrations between the alternator and the turbine and, if no steps are taken to improve the power factors of the loads which are causing the problem, such vibrations could quickly wreck the turbine/alternator shaft's bearings. : Real-world alternators have to handle out of phase currents but, for the reason implied by this exam question, such currents must always be minimized. : Electric power utility companies always monitor their output for the appearance of any new heavy out of phase current loads. If they see any they take strong action to enforce their supply contract terms to make the consumers who are responsible disconnect their damaging loads until the appropriate power factor correction equipment has been installed. To view or take part in the Discussion click on the View Discussion button below. Important Note: To find out how it should be done in a safe and legal manner, before you try to connect a generator to your home electricity circuits you would be very wise to read the answer to the Related Question shown below: "How would you connect a generator when the power is off?". : ALWAYS CHECK WITH YOUR LOCAL WIRING SAFETY OFFICE BEFORE YOU ATTEMPT TO CHANGE ANYTHING : - ELECTRICAL SERVICE PANEL, BREAKERS, CABLES OR OUTLETS - : ON ANY ELECTRICAL POWER CIRCUITS : IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS. If you do this work yourself, always turn off the powerat the breaker box/fuse panel BEFORE you attempt to do any work ANDalways 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. .
Are voltamps equal to watts?
Yes, in direct current (DC) circuits where the voltage and current are in phase, voltamps (VA) are equal to watts (W). However, in alternating current (AC) circuits where the voltage and current may not be in phase, the relationship between voltamps and watts can vary depending on the power factor of the load.
What is meant by 12V 60 VA?
This means the device operates at 12 volts and consumes 60 volt-amperes (VA) of power. VA is the apparent power, which includes both the real power (watts) used by the device and the reactive power due to inductance or capacitance.
What is LPF?
LPF is Low power factor, which is used to calculate overall power in VA (voltamps) kind of like calculating overall power in watts.
What is the difference between voltamp and watt, and how do they relate to each other in terms of measuring electrical power?
A voltamp is a unit of apparent power, which is the combination of voltage and current in an electrical circuit. A watt, on the other hand, is a unit of real power, which is the actual power consumed by a device. The relationship between voltamps and watts is that in an ideal circuit with no reactive components, the apparent power (voltamps) is equal to the real power (watts). However, in real-world circuits with reactive components like inductors and capacitors, the apparent power can be greater than the real power due to the presence of reactive power.
What is difference between MVArh MWh and MVah?
All three refer to a form of power. Active power units use watts, apparent power uses voltamps, and reactive power uses voltampreactives. So, they are Wh, VAh, and VARh. The M is the prefix for Mega, meaning 10^6.
Can the use of a violet wand cause damage to other electronic equipment with in a home?
Being a device that discharges voltage (even a small amount of electon flow, commonly called amperage) can disrupt or damage electonics. Extent would depend on the amount of VA (voltamps) as well as the particular electronics in question (how well it is grounded, shielded, what sensitive components exposed and other variables). Even without direct current flow any electronic 'generator' creates EMF (electromagnetic force) which can affect (such as RF (radio frequency)) or any component within a certain area that is susceptible to EMF. All this said, with 'normal' usage (read: no direct contact or extreme close proximity) MOST (read: well designed and produced) electronics are not affected within a building (household). I wouldn't use one on myself if I had a pacemaker though (disclaimer: I am not a doctor or engineer). Always use common sense and care when using any electronic device that could potentially injure or damage! Being a device that discharges voltage (even a small amount of electon flow, commonly called amperage) can disrupt or damage electonics. Extent would depend on the amount of VA (voltamps) as well as the particular electronics in question (how well it is grounded, shielded, what sensitive components exposed and other variables). Even without direct current flow any electronic 'generator' creates EMF (electromagnetic force) which can affect (such as RF (radio frequency)) or any component within a certain area that is susceptible to EMF. All this said, with 'normal' usage (read: no direct contact or extreme close proximity) MOST (read: well designed and produced) electronics are not affected within a building (household). I wouldn't use one on myself if I had a pacemaker though (disclaimer: I am not a doctor or engineer). Always use common sense and care when using any electronic device that could potentially injure or damage!
Is it cheaper to run 240 volt?
NO, if you have motors that are 'convertable' -110 or 220/240, the higher voltage is more economical. <<>> It costs the same regardless of whether the voltage is 120 or 240 volts. The bonus of using a higher voltage is on the installation wiring costs. At a higher voltage the current of the device is lower. This lower amperage permits a smaller size wire to be used. This only really becomes a cost saving factor in larger equipment. In small power tools the higher voltage range will allow you to double the distance from the supply source to the place where the power tool is needed.
How does increase in VAR cause increases in bearing damage caused by shaft vibration in the shaft connecting turbine to generator in a 210 MW turbine-generator set?
Another answer which was given to this question is now in the Discussion Area. It gives advice about running small domestic motor-generator sets but does not address the actual question here which is about the kind of turbine-alternator set used in a major power station capable of generating up to 210 MegaWatts of power. Because of the highly technical details given in the question it is clear that it is probably from an exam in electrical engineering and not one on electrical wiring. The full answer to this question would take a chapter in a heavy book about the design of turbine-alternator sets, the kind usually held in an engineering/technical library! Whilst the student should really use his recommended course materials, for those who may be interested this may be a possible part-answer: : VAR means "VoltAmps Reactive". : In the ideal world there would only be purely resistive loads so that there would be no large currents out of phase with the generated voltage taken by loads having high power factors. : Such out of phase currents can easily lead to shaft vibrations between the alternator and the turbine and, if no steps are taken to improve the power factors of the loads which are causing the problem, such vibrations could quickly wreck the turbine/alternator shaft's bearings. : Real-world alternators have to handle out of phase currents but, for the reason implied by this exam question, such currents must always be minimized. : Electric power utility companies always monitor their output for the appearance of any new heavy out of phase current loads. If they see any they take strong action to enforce their supply contract terms to make the consumers who are responsible disconnect their damaging loads until the appropriate power factor correction equipment has been installed. To view or take part in the Discussion click on the View Discussion button below. Important Note: To find out how it should be done in a safe and legal manner, before you try to connect a generator to your home electricity circuits you would be very wise to read the answer to the Related Question shown below: "How would you connect a generator when the power is off?". : ALWAYS CHECK WITH YOUR LOCAL WIRING SAFETY OFFICE BEFORE YOU ATTEMPT TO CHANGE ANYTHING : - ELECTRICAL SERVICE PANEL, BREAKERS, CABLES OR OUTLETS - : ON ANY ELECTRICAL POWER CIRCUITS : IF YOU ARE NOT ALREADY SURE YOU CAN DO THIS JOBSAFELY AND COMPETENTLYREFER THIS WORK TO QUALIFIED PROFESSIONALS. If you do this work yourself, always turn off the powerat the breaker box/fuse panel BEFORE you attempt to do any work ANDalways 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. .
