But, that doesnât mean students have to take them all in the same week. Our class structure allows us to provide 5 cycles of classes for every 30-day period. As long as students take the classes in order, (Class 1, Class 2, Class 3, Class 4), they are free to switch between any of the cycles for that 30-day period. The only other requirement is that all 4 classes must be completed within 30 days of the first class.
Re: Advantages of three phase systems over single phase. The big advantage with 3 phase mains is that any electric motor connected to it is more efficient, has smother running and uses less parts so is more reliable. There is also a slight advantage in using 3 phase transformers over single phase ones.
This allows for 240 V three phase as well as three different single phase voltages (120 V between two of the phases and the neutral, 208 V between the third phase (known as a high leg) and neutral and 240 V between any two phases) to be made available from the same supply.n a three-phase system the phases are spaced equally, giving a phase separation of one-third cycle. The power frequency is typically 50 Hz in Asia, Europe, South America and Australia, and 60 Hz in the US and Canada (but see Mains power systems for more detail).