# 3 phase full wave uncontrolled bridge rectifier

#### dharanimoka

Joined Jan 29, 2018
18
How can the rms value of the line current or the rms value of the secondary transformer current be calculated. I have searched other sites and they have always just put the final equation, I want to know how it is derived.

#### Ramussons

Joined May 3, 2013
1,064

#### dharanimoka

Joined Jan 29, 2018
18
I think my question is not been properly worded. In the three phase full wave bridge rectifier the RMS current of supply is calulated as shown in the picture C. Can someone explain me how is that calculated. I am somehow not understanding this. Is the 2 in 2/Pi in the equation due to the 2 pulses in the current waveform?

#### MrAl

Joined Jun 17, 2014
8,483
I think my question is not been properly worded. In the three phase full wave bridge rectifier the RMS current of supply is calulated as shown in the picture C. Can someone explain me how is that calculated. I am somehow not understanding this. Is the 2 in 2/Pi in the equation due to the 2 pulses in the current waveform?
Yes. Instead of integrating the more complex waveform from 60 to 180 degrees they go from 60 to 120 which is 1/2 of the total waveform and then multiply by 2. This way they dont have to deal with two sine waves just one as they are identical in effect. The pi is the period. The entire calculation is for RMS.

• dharanimoka