| ??? 02/19/05 01:13 Read: times |
#87927 - Distortion of mains Responding to: ???'s previous message |
Prahlad said:
Now the problem is the values calculated using the RMS factor table do not match the practically measured values. All these calculations and tables assume, that mains voltage is stable. But it is not, neither in amplitude nor in shape! Keep in mind, that the power station which delivers the mains voltage suffers from a certain source impedance. Depending on what other loads are connected to mains you will never have exact nominal voltage. And if some of these loads have phase angle control, then your mains additionally gets distorted, the more the higher the source impedance of power station is. Human eye is not a good instrument to estimate distortion of mains sine. Once I measured distortion of mains by the help of a notch filter and was surprised to have more than 10%, although it looked perfect with eyes. Kai |
