What happen if we connect different frequency bus?

Recently someone with very curious mind asked this question in linked in :

If we connect a 50Hz bus bar with 60Hz bus bar then what would be results, does frequency of both system will be changed or any other effects ?

We can breakdown this question :

1. What is the result of combining two different frequency?

2. Are there any effects to system?

Answer :

The first question can easily answer by using simple frequency addition, or you can use oscillator to visualize the frequency addition. So the result is really clear now.


1 Hz


3 Hz


3 + 1 Hz




The second question depends on system design an purpose, generally black box system consist of input, output and processing blocks. In ideal environment your whole system won’t get interfere from output line (in practical world we get load effect).

In practical example we can find this case in multi grid power plant, we need to make sure that each generator has same frequency and at the same phase. Power plant need to produce smooth sinusoidal wave from its system with many generator.