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Are high voltage tests on current power transformers recommended and if not why?
Wiki User
∙ 14y ago
Hi-pot and megger tests are common to check the insulation on Transformers, motors, refrigeration compressors, etc. They help check the condition of equipment to avoid a future falure. High votage test are conducted in current transformers by shorting the seconday and earth,can apply 3 times the rated voltage
Wiki User
∙ 14y ago
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If voltage and current are proportional why do they increase voltage in powerlines in order to decrease current?
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.
Leading and lagging power factor?
The terms, 'leading' and 'lagging' refer to what the load current is doing, relative to the supply voltage (Phase difference) -never the other way around. If the current is leading the voltage, then the power factor is 'leading'; if the current is lagging the voltage, then the power factor is 'lagging'.
Which power is product of voltage and current in a circuit calculated without considering the phase shift that may be present between the voltage and current?
I'm not sure there is a term other than "power"; V*A, or the vector sum of real and reactive power is equivalent to the power calculated by multiplying the voltage times the current, ignoring phase shift.AnswerThe product of voltage and current in an a.c. circuit is called 'apparent power', expressed in volt amperes, in order to distinguish it from 'true power' (in watts) and 'reactive power' (in reactive volt amperes).
What does it mean to have a power factor of 1?
First we need to know what is power factor ? it's cosine of angle between the current and voltage at that point where we wish to measure it. so power factor of "1" means the angle between the voltage and current is 0 degree. It means literally that the current and voltage is in the same phase.
What are transformer used for?
Transformers change the numbers of volts, watts, and amperes of the electrical current, from those in the power source to those needed for the mechanism. Generally, transformers are used to change the input voltage to a desired value of output voltage. Typically, transformers step up (increase) the voltage, or step down (decrease) the voltage. There are many applications and uses for transformers - most of these embed the transformer in another device, so you do not see (or even know about) the transformer. A computer power supply, for example, has a transformer embedded in it that converts the incoming 120 volts into both 12 and 5 volts. As another example, when travelling from North America to Europe, travelers often take with them an adapter that includes a step-down transformer that converts the European 220 volts into the 120 volts that the North American appliances require. Note that the transformer cannot change the frequency of alternating current, and so some 60 Hz North American appliances will not work properly in Europe, even with a proper step-down transformer, because European power is distributed at 50 Hz. Similarly, some 50 Hz European appliances will not work properly with 60 Hz North America power, even with a proper step-up transformer. Transformers are also included in adapters for electronics, such as for a cell phone charger. A transformer inside the adapter reduces the incoming 120 volts into a lower voltage (sometimes, 3, 5, 6, 9, 12 or some other value of volts) that the cell phone can accommodate. Such electronic adapters (and the computer power supply, noted in the example above) often include a rectifier that also converts the alternating current (AC) into direct current (DC), which reduces peak-to-peak voltage without affecting RMS (root mean square) voltage. Most transformers have fixed ratios, meaning the output voltage is always a constant fraction of the input voltage. The output of these fixed ratio transformers will fluctuate in proportion to the fluctuation of the input voltage. Some transformers are variable ratio, meaning you can adjust (either manually or automatically) the ratio of output to input voltages. Automatic variable ratio transformers are typically used to output a constant voltage, regardless of how much the input voltage fluctuates. Also to destroy the decepticons.
What are the advantages of power transformers over voltage transformers?
Power transformers can be used for power transformation. Voltage transformers are not suitable for high power applications.
Certain electric devices such as cordless telephones have small transformers that plug into walls.what do the transformers do?
Transformers are relatively simple devices which change both the current and the voltage of an electric source without affecting the total amount of power being given. Power, as the product of current and voltage, is mostly conserved as transformers are used, but the current and voltage changes. If the device needs just half the voltage of what is coming out of your wall (240v in Australia), then it will 'step down' this voltage by half, but will have to 'step up' the current, so your voltage will halve, your current will double, but the total amount of power will remain the same. Essentially the transformer exists to give your device the required input of electricity so your device is not fried!
What is a device that changes electric current into a different voltage?
Nothing can change electric current to voltage. You can compare "current " to rate of flow, while "voltage" is the energy level. Transformers can be used to increase or decrease the voltages of alternating current as is done from 'street power' to domestic power.
What is a transformer and its functions?
Voltage transformer or potential Transformers are used in conjunction with Current transformers for metering and protection purpose in HT and LT power system.
Does transformer doubles the power?
No. Power is constant. Transformers neither increase nor decrease power, except for minor losses. They increase or decrease voltage, and they decrease or increase current, but the product of voltage and current, i.e. power, remains the same.
What initiated the change into ac system from dc system?
The need for more and more power. In a fixed voltage system like DC, power is proportional to current, and current is related to conductor size. In order to have more power, you had to have larger conductors, and it was becoming unwieldy. With AC, we could use transformers to step up the voltage. Power is now proportional to both current and voltage, but current is still only related to conductor size, which means that with higher voltage, you could transfer more power with smaller conductors. Transformers would step up the voltage at the substation for transmission and distribution, while transformers on the poles would step it back down for small groups of services.
Why you use transformers to transfer power?
Transformers do not exactly transfer power, they either step up voltage or step down the voltage from one source to another to make it a useable voltage.
What equation relates power to current and resistance?
Power = (current) times (voltage)Current = (Power) divided by (voltage)Voltage = (Power) divided by (current)
Current Transformers Manufacturers?
Macroplast Transformers is a leading Current Transformers Manufacturers in India. Current transformers are devices that transform higher current value to lower current value. Current transformers provide galvanic isolation from the voltage on the primary winding while simultaneously creating a power signal that has been converted to a standard level, which in turn permits the use of standard measurement instruments and relays. For more info contact us.
Why is a transformer used?
To step up or step down a particular voltage using the principle of electromagnetic induction. This is a potential transformer. Transformers are also used to step up or step down current. Current transformers are used extensively in instrumentation applications. Current and voltage are inversely proportional.
Why you step up or step down voltage why not current?
The current is automatically stepped up or down when the voltge is stepped down or up by a transformer.Most transformers are designed for a constant voltage, and the current varies depending on the load. Current transformers are also made to detect the current in a power cable so that it can be measured.Another AnswerIt's a misconception that transformers step current up or down (with the exception of current transformers, that is!). Transformers step voltages up or down. The secondary current is determined by the load. If there is no load, then there is no secondary current; if there is a heavy load, then there will be a heavy secondary current.The secondary current then determines the primary current, because the primary power must match the secondary power (ignoring losses), so if the secondary current increases, so must the primary current. The current itself isn't stepped up or down. Normal transformers work with constant-voltage supplies and are designed to step the voltage up or down, and the current is incidentally stepped down or up in the same ratio as the voltage.Current transformers are designed to step current up or down (usually down), and are used most commonly to sample the current in power conductors.
What is the relationship between voltage power and current?
The unit of power is watts, the unit of current is amps, and the unit of voltage it volts. Power = Voltage X Current Voltage = Power / Current Current = Power / Voltage In electricity, power is symbolized with a P, current with an I, and voltage with a V. The real formula looks like: P = V x I V = P / I I = P / V
