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Zero Crossing Contact


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Line voltage  is basically AC voltage (Alternating Current) . Mention as alternating because the value is not fixed but always changes with time, following sinusoidal pattern, as can be seen on graph bellow
. I live in Indonesia so I use 220V 50Hz as example on following graph.


ZCC



Every cycle of line electricity always starts from zero point, then goes to the first peak value which is called positive peak, back again to zero value, then goes to the second peak called negative peak, and finally returns to zero point
This cycle occurs continuously, for countries with 50Hz of electric frequency, this cycle occurs 50 times per second, and for countries with 60Hz of electrical frequency, this cycle occurs 60 times per second.
In this world there are basically only two types of electrical frequencies namely 50Hz and 60Hz.

When the audio equipment is turned on manually, the value of the line voltage can be in various possible positions on the line  electricity graph above.
The most desirable timing when the audio equipment is turned on is when the value of the  line voltage is at zero point, because when the equipment is turned on at this point the starting current will be minimum or close to zero and the MCB (miniature circuit breaker)  in our home will not turn off.
On the other way, if the equipment is turned on when the line voltage is at Peak position, either at Postive Peak or Negative Peak, the starting current will have a maximum value, and if your equipment has a large power consumption, then there is a possibility that the MCB in your home will turn off.

Active Fuse works on the principle of Zero Crossing Contact. When Active Fuse is turned on, it does not directly connect line electricity to the equipment, but it will monitors first  whether the line  electricity value  is at zero point or not, if it is already at zero point, then line electricity is connected to the equipment, so that the MCB at home is not will turn off.