VAC would be the abbreviation of Volt Altern Current which would be translated Volts of alternating current. The difference between VDC is that its sinusoidal oscillation achieving a more efficient energy transmission.

The alternating current is the energy that we receive in our homes, it is generated in the power plants by means of alternators.

The intensity of this type of current varies with time, and changes direction 50 times throughsecond (50hz). The generated voltage changes in the form of sine wave so it is not constant.

In the image:

1. Current by pulsations.
2. Direct current (DC).
3. Alternating current (AC).
4. Variable current.

The PLC is a system to connect the Ethernet network using the common electrical cable into any home or office. Take the electric network into a digital network that transmits data at almost the same speed as if a network cable is connected. It is a technology that is catching many followers by ease of installation, as between the two PLC is not necessary to use any network cable. The PLC systemHomePlug connects two, where one of them is connected by a cable to the network and the other is connected to a computer or other device via the network cable. The PLC converters transmitted in range of medium and high frequents. Asymmetric speed can reach 2.7 Mbit/s.