over heating is the contributory cause.
Power factor is the cosine of the phase angle between voltage and current. In a resistive load, current is in phase, i.e. with a phase angle of 0 degrees, with respect to voltage. Cosine (0) is 1.
There is no angular gap between voltage & current in Direct Current. So power factor is always cos 0 deg. i.e. 1 for all tha cases of DC.
A resistor doesn't have a power factor. However, if a circuit is pure resistance in nature the power factor will be one when a voltage is applied and a current flows in the circuit. The power factor is a measure of the relative phases of the current and voltage in a circuit.
VA Rating stands for Volt-Ampere Rating, It is the basic unit of Alternator or Transformer. This is so because in AC System Power(P) is the product of Voltage(V),Current(I)and Power Factor. Power(P) = Voltage(V) * Current(C) * Power Factor But power factor of the load is never constant and depends on the type of load. So to resolve this problem power ratings of the above mentioned machine is always rated in VA or KVA and its the product of voltage and current.
'Displacement power factor' is the technically-correct term used to describe the cosine of the phase angle (i.e. the angle by which the load current leads or lags the supply voltage) due to the reactance of a load. Usually, when we talk about the 'power factor' of a load, we mean 'displacement power factor'.However, another type of power factor can exist in a circuit, due to the presence of harmonics in the current waveform, due to non-linear loads such as SCR rectifiers. This type of power factor is temed 'distortion power factor', and may be corrected using filters.So, the terms 'displacement' and 'distortion' are used whenever it is necessary to clarify these different types of power factor.
With varying power factor the load current drawn changes, which in turn affects the voltage regulation
for controlling a motor if it is in a important application we use rectifiers because the ripple factor of the chopper is very high in comparison with choppers
Single phase rectifiers are suitable to power loads of up to only about 15 kW. For higher power demands, three phase rectifiers are preferred for the following reasons: Higher dc voltage, better TUF, better input power factor, less ripple content in the output current - therefore giving better load performance and a smaller size of filter circuit parameters because of the higher ripple frequency.
1. Efficiency of full wave rectifier is better than other rectifiers i.e, Efficiency()=81.2%. 2.It's Peak Inverse voltage (P I V)=2Vm.
It would be unity, or 1.0. Since the voltage in a DC circuit does not vary with time, there can be no phase displacement of the current waveform, and therefore the current could not lead or lag the voltage waveform.
Power factor can also be equal to 1. Power is greatest when voltage and current are in phase; the "power factor" is used to specify how much less the power is, compared to the product of voltage x current, if they are not.
Because the value form factor is 1.1 that's why transmission line voltage is always in a multiple of eleven.
extinction angle control is a scheme of forced commutation for power factor improvement in phase controlled convertors/rectifiers. In this scheme the firing angle is adjusted in order to get the desired output or load voltage. By varying the value of extinction angle we can get the desired load voltage and current waveform.......submitted by abhimanyu(sunny)
Power factor is the cosine of the phase angle between voltage and current. In a resistive load, current is in phase, i.e. with a phase angle of 0 degrees, with respect to voltage. Cosine (0) is 1.
Bridge rectifiers have higher rms values because the ripple factor low.
that is called a form factor which is always b 1.1
A pure resistive load always has a power factor of one. This is because the current and voltage waveforms are in phase in an AC circuit.