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Electrical Terminology

NAC-Trainer April 24, 2020

When following our online training material we will use electrical terminology on almost every page. Below, you will see the electrical terminology we will refer to often and what it means.

Voltage (V)

Voltage (VAC or VDC) – The term voltage is used to describe pressure in the wire or another electrical component. This ‘Push’ is what causes the current to flow through a circuit. Voltage is measured in AC (Alternating Current) or DC (Direct Current). The symbol for volts is V (This can be written as 24 V or 24 volts) and can be followed up with the voltage type (24 VAC or 24 VDC) example – a washing machine heater requires 240 VAC

The voltage can also be referred to as ‘Potential’. Electrical potential is the amount of energy required to move a unit of electrical charge from one point to another through a circuit. 1 volt is one unit of electric potential. This calculation is done at the point of manufacturing and when designing a circuit the manufacturer will calculate what potential is required at the component level. As a service technician, your job is to ensure when diagnosing a component that the correct potential is being supplied. AC components in the UK are designed to be operated at 230 VAC. DC components generally operate at a much lower voltage (e.g 12 VDC) so components are used on a PCB to step down the voltage and convert it to DC if required.

Alternating Current (AC)

AC voltage cycling 50 times a second

In the UK our national power grid is supplied by Alternating Current. Every UK household has 230 VAC to their home and as such household appliances are designed to be supplied by a 230 VAC supply. Alternating Current periodically reverses direction. In the UK this is done 50 times a second (50Hz). AC current is generated in power plants using turbines that are powered by steam. This is why the current alternates from negative to positive.

Direct Current (DC)

Direct Current over 1 second

Direct Current is usually supplied by a cell or battery and is described as a unidirectional current. When a component requires DC current to work it is converted from an AC supply using a rectifier, this is referred to as ‘Dirty DC’. In domestic appliances, DC components are usually low voltage (e.g 24 VDC)

Hertz (Hz)

When we use the term Hertz (Hz) it is used to describe the frequency. In electricity, we use Hz to describe how often something cycles in a second. In the UK, the AC national power grid is supplied at 50Hz. So that means the AC supply goes through positive to negative cycles 50 times a second.

Ampage (I)

Amps (I or amps) – When we refer to amps (Short for Ampere) we are referring to the amount of current that is flowing through a circuit. The larger the number the more current is flowing through the circuit. For example – a cooker requires hardwiring to a 32 amp circuit

Resistance (R or Ω)

Resistance (Ω or Ohms) – Ohms is a unit of measurement for the amount of resistance required for current to the flow through the circuit. When testing with a multimeter a 1-volt current is applied to the circuit or component so the meter can calculate what the resistance is. example – when testing a cooking element, I got a reading of 24Ω

Power (P, W or Watts)

Wattage (Watts or W) – Wattage refers to the rate at which electrical energy is consumed by a component. It is commonly referred to as power (P) and it doesn’t necessarily just apply to electrical components. It can also be used in mechanical systems. For example – the heater in the dishwasher is 1800W

60W Lamp
100W Lamp
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