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Why you use low power factor wattmeter on primary and unity power factor on secondary side of transformer?
Wiki User
∙ 9y ago
There is no such thing as a 'low power-factor' wattmeter. A wattmeter always reads true power, regardless of the load's power factor.
Wiki User
∙ 9y ago
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Why low power factor wattmeter is used for open circuit test of transformer?
For open circuit test of transformer, the secondary is open circuit and the circuit impedance is largely inductive due to the core impedance having high L as compared to R. hence the power factor is reduced, thus , we use low power factor wattmeters.
How do you calculate input voltage of a transformer given both side high and low side impedances and also load with power factor?
The input voltage (primary) and output (secondary) of a transformer is determined by the manufacturer. Transformers are bought to accommodate the voltage that is needed on the primary side and to what voltage is needed on the secondary side.
What are common efficiencies for transformers?
Transformer utilization factor is the ration of power delivered to the load and ac rating of the transformer secondary.
What are the limitations of power supply?
Power limitation transformer circuit structure of power supply, including: an electromagnetic interference filter unit, a rectifying unit, a power factor correction section, a transformer having a primary input terminal and secondary input terminal, a pulse controlling unit connected with the secondary input terminal of the transformer, a primary power limitation circuit and at least one secondary power limitation circuit, an output current controlling unit and an output voltage controlling unit. The input terminal of the output current controlling unit is connected with the secondary output terminal of the transformer. The primary output terminal and secondary output terminal of the output current controlling unit are respectively serially connected with the primary and secondary power limitation circuits. The input terminal of the output voltage controlling unit is connected with the secondary output terminal of the transformer. The output terminal of the output voltage controlling unit is connected with the secondary power limitation circuit for controlling the magnitude of the voltage and current of the primary and secondary power limitation circuits so as to control the output power.
Why you use upf wattmeter for short circuit test on load test on single phase transformer?
If, by 'upf', you mean 'unity power factor', then allwattmeters measure the in-phase component of the load current, so the term is quiet unnecessary.A short-circuit test is used to determine the (true) power loss in the transformer, which is exactly what a wattmeter measures
Why low power factor wattmeter is used for open circuit test of transformer?
For open circuit test of transformer, the secondary is open circuit and the circuit impedance is largely inductive due to the core impedance having high L as compared to R. hence the power factor is reduced, thus , we use low power factor wattmeters.
How do you calculate input voltage of a transformer given both side high and low side impedances and also load with power factor?
The input voltage (primary) and output (secondary) of a transformer is determined by the manufacturer. Transformers are bought to accommodate the voltage that is needed on the primary side and to what voltage is needed on the secondary side.
What happens to the current as the voltage is increased by the step up transformer?
Compare a transformer to a balancing act. Both side need to remain equal.The primary side of the transformer is the supply side and the load is connected to the secondary side of the transformer.The load governs the current of the secondary side of the transformer and the voltage of the secondary side must match the voltage that the load required to operate.The ratio of the transformer will determine what the voltage of the secondary side is as compared to the voltage that has to be applied to the primary.The current of a step up transformer will be higher on the primary side that that of the secondary.Apply voltage and current to this concept and you will see that the transformer will remain balanced.The size of the transformer is always calculated from the secondary side of the transformer and the value is written in VA or KVA where V = voltage and A = amperage. Power factor is also taken into consideration when calculating the size of the transformer to be used.
Can a transformer step up power?
It is a basic tenet of physics that, in a closed system, energy can neither be created nor destroyed. Energy can, however, be transformed. It follows from this that the power output from a system cannot exceed the power input. Therefore, in a transformer, the primary power and the secondary power are always equal (at least in theory). A transformer can step voltage up or step it down. Since power equals voltage multiplied by current then, if the transformer secondary voltage is stepped up, the current must be stepped down by the same factor (that is, if the voltage is stepped up by a factor of 4 then the current is stepped down by a factor of 4). Any increase in voltage in the secondary of a transformer will result in a corresponding inversely proportional decrease in secondary current. From a practical standpoint, secondary power is always somewhat less than primary power due to resistive losses in the transformer windings as well as eddy current and hysteresis losses (magnetic losses) in the transformer core. These losses produce heat which compounds the transformer inefficiency. The primary and secondary windings are made from copper and, like all metals, it has a positive temperature coefficient of resistance. This is a fancy way of saying that when the copper windings of a transformer get hotter their electrical resistance goes up which further increases the resistive losses in the transformer.
Difference between step up and step down transformers?
Actually an isolation transformer may be physically the same as a Step up/Step Down transformer. The main difference is in the way they are used. Another difference is that in a normal transformer there will be capacitance between the 2 windings, between the windings and core, between the core and shell, etc. These capacitances bring in high frequency noise from outside, which will be transmitted in the secondary circuit. So [in an isolation transformer] wires are connected between each component, (not direct contact, but with insulation present). This permits a leakage current and eliminates unnecessary capacitance. I could make a start to answer this question. Isolation transformer: is a transformer with two separate windings, the primary and the secondary. There is an electrical isolation between the primary and the secondary. Nearly any type of transformer with two non-connected windings could be considered an "isolation" transformer, in that it electrically isolates the primary voltage from the secondary voltage. There are also transformers with one winding (called auto-transformers) and connections for input and output. If the input is low voltage and the output a higher, then you can say it is a STEP-UP transformer. If the input is high and the output is low, then you can say it is a STEP-DOWN. This type of transformer can not by used where safety is a large factor.
What are common efficiencies for transformers?
Transformer utilization factor is the ration of power delivered to the load and ac rating of the transformer secondary.
What are the limitations of power supply?
Power limitation transformer circuit structure of power supply, including: an electromagnetic interference filter unit, a rectifying unit, a power factor correction section, a transformer having a primary input terminal and secondary input terminal, a pulse controlling unit connected with the secondary input terminal of the transformer, a primary power limitation circuit and at least one secondary power limitation circuit, an output current controlling unit and an output voltage controlling unit. The input terminal of the output current controlling unit is connected with the secondary output terminal of the transformer. The primary output terminal and secondary output terminal of the output current controlling unit are respectively serially connected with the primary and secondary power limitation circuits. The input terminal of the output voltage controlling unit is connected with the secondary output terminal of the transformer. The output terminal of the output voltage controlling unit is connected with the secondary power limitation circuit for controlling the magnitude of the voltage and current of the primary and secondary power limitation circuits so as to control the output power.
Where should power factor correction capacitors be added - to the primary or secondary side of a drive isolation transformer?
The primary. Many drives do not allow you to connect PF caps directly at the drive. It messes with DC the power supply.
Why the rating of transformer in kva?
because we dont know power factor of the secondary laod
Why you use upf wattmeter for short circuit test on load test on single phase transformer?
If, by 'upf', you mean 'unity power factor', then allwattmeters measure the in-phase component of the load current, so the term is quiet unnecessary.A short-circuit test is used to determine the (true) power loss in the transformer, which is exactly what a wattmeter measures
What is the electrical current in electrical transformations?
In the case of a transformer the simplest way to explain current is that it will be inversely proportionate to the voltage. For example: If you have a transformer that transforms 5000 volts down to 2500 volts you have a 2:1 ratio. The current ratio will then be 1:2. If you had 200 Amps on the 5000 volt side you will have 400 Amps on the 2500 volt side. Comment There is a misconception that a transformer will 'step up' or 'step down' the primary current. In fact, the secondary current is determined by the secondary voltage and the impedance of the load, NOT by the primary current. The secondary current then determines the primary current by a factor equivalent to the reciprocal of the turns ratio.
What is the use of transformer utilisation factor?
It tells us how much is the transformer utilised in a given process. For a rectifier,TUF =(D.c.power delivered to the load)/(power rating of transformer secondary)
