TENSION
The Voltage or Voltage is the one that makes a measurement, so to speak of two points of entry or exit of an electrical system, this in turn can be measured by a device called a multimeter. The unit of measurement for the voltage is the Volt. It is always necessary to have two points with different voltages, for example A = higher voltage - B = lower voltage. In short, it is only necessary to put voltage to a system so that the load (mentioned in a previous post) begins to circulate through a driver and can power a device, such as turning on a lamp for example. Currently there are devices that are measuring the voltage that you have in the input as in the transformers in the substations, either to take a control but the most important thing is the protection of the system, if they detect any anomaly they can trigger or interrupt the power supply.
POWER
The power can be found as P, to transfer energy from one point to another is spent energy, the transfer of energy is called as watt. The power absorbed must be proportional to the number of coulombs transferred per second, or as we call it before current and as mentioned in the previous paragraph, to move that current the voltage is needed, therefore we can define that: P = V * I . With this formula to clear it we can find the value of the current or voltage if it is what we require in any case. If any anomaly can trigger or interrupt the power supply.
