The key to understanding how brewers or any type of Espresso or brewing work is to have a basic understanding of the basic of electricity. The goal of this article is to give a clear simple explanation of how these systems work. With that you can better understand how each system works. The explanations in the article are by no means replacement for a good solid educational course
First and most important: Electrical Safety. Electrically powered equipment can pose a significant hazard to workers if mishandled or not well maintained. Many electrical devices have high voltage or high-power requirements, carrying even more risk. Major hazards associated with electricity are electrical shock, fire and arc flash. Electrical shock occurs when the body becomes part of the electric circuit, either when an individual meets both wires of an electrical circuit, one wire of an energized circuit and the ground, or a metallic part that has become energized by contact with an electrical conductor. Water is a great conductor of electricity, allowing current to flow more easily in wet conditions and through wet skin. The effect of the shock may range from a slight tingle to severe burns to cardiac arrest. Keep in mind Safety First.
Waterfalls: Electricity is frequently thought of as an invisible fluid that moves through some materials better than others and performs work. Using the analogy of a waterfall; voltage represents the height of the waterfall: the higher it is, the more potential energy the water has due to its distance from the bottom of the falls, and the more energy it will possess as it hits the bottom. Current represents how much water was going over the edge of the falls each second. Resistance refers to any obstacles that slows down the flow of water over the edge of the falls (e.g. rocks in the river before the edge).
Voltage: Measured in Volts. Using the fluid analogy voltage is a measure of the pressure that is required to move that fluid through whatever it is moving through. No Voltage (pressure), no movement; just as there is no movement of water through your garden hose if there is no pressure to move it.
Current: Measured in amperes (amps). It is the amount of electricity that is moving through whatever it is moving through as pushed by the Voltage (pressure). If this were water, we would call flow rate.
Power: Measures in Watts. A watt is a measurement of how much “work” can be done with the electricity flowing through a circuit. Watts are the voltage multiplied by the current. I.E. 50 volts at 2 Amps is 100 watts just as 25 volts at 4 amps is also 100 watts. If this were water, we’d multiply the gallons per minute by the pressure.
Resistance: Measured in Ohms (Ω). The measure of how much a wire (or anything) resists the movement of electric current through it. If this were water, it could be the resistance caused by a kinked hose. It can resist, or it can stop the flow depending on how kinked it is. For electricity, it generally depends on the material the wire is made of, how big the wire is, and how long it is.
Continuity: Is the presence of a complete path for current flow. How well something conducts, or sometimes used to describe if it conducts at all;
“This wire has no continuity!”