This is done as current flows though one half of the winding for positive half cycle and through another half of the winding for negative half cycle. Here we need to individually find the VA rating of transformer primary and secondary and then take average of their values. The method for finding transformer utilization factor of center tapped rectifier is a bit different than other type of rectifier.
#Ac to dc bridge rectifier calculator full
Transformer Utilization Factor (TUF) of Center Tapped Full Wave Rectifier This is quite poor utilization of transformer. For example, the VA rating of required transformer for 100 watt load will be around 350 VA (0.35×100 = 350). It means that the VA rating of transformer required for half wave rectifier is approximately 3.5 times (1/0.2865 = 3.5) of the DC power output. The transformer utilization factor of half wave rectifier is 0.2865. TUF = DC Power Output / VA Rating of Transformer Hence, transformer utilization factor of half wave rectifier can be calculated using the definition. Thus, the VA rating of Transformer = (V m/√2)(I m/2) One thing, I am repeatedly mentioning source, here source means transformer secondary. As the rms value of load current for half wave rectifier is equal to (I m/2), therefore the rms value of source current will also be equal to (I m/2). This means, the rms value of the source current will be equal to the rms value of the load current. Why so? This is just because of transformer action. But the source current is not sinusoidal for half wave rectifier rather it is governed by the waveform of the load current. Since the voltage of source is sinusoidal, therefore its rms value will be equal to (V m/√2). Now, we need to find the effective VA rating of Transformer. Similarly, the average or dc voltage output is equal to (V m/π).ĭC Power Output, P dc = Average Current x Average Voltage Well, the average or DC output current is for half wave rectifier is equal to (I m/π) where I m is peak value of output current. To calculate the DC power output, we need to know DC output current and voltage of the half wave rectifier. It does not flow during the negative half cycle as the diode is reversed biased during this halt time period. In this rectifier circuit, the output current flows only during the positive half cycle of the supply voltage. Half Wave Rectifier is the simplest rectifier circuit configuration employing only one diode to convert the AC input into DC. Transformer Utilization Factor (TUF) of Half Wave Rectifier Let us now calculate the value of transformer utilization factor for half wave center tapped full wave and bridge rectifier one by one. This is the reason TUF is a performance evaluation parameter of a rectifier. But the performance of rectifier can of course be judged from the utilization of VA rating of transformer. It is independent of rectifier performance. VA rating of transformer is fixed and can be found on the name plate.
But in TUF, instead of AC power input, VA rating of transformer secondary is used for calculation. Mind that, rectification efficiency is the ratio of DC power output to the AC power input of the rectifier. Basically, these are two different parameters. Many times, transformer utilization factor is confused with efficiency of rectification. In other words, the VA rating of required transformer will be less if TUF is more and vice versa. The more the value of TUF, the more will be the utilization. Transformer utilization factor is a quantitative indication of the utilization of VA Rating of Transformer.
The formula for TUF can be written as below.
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