Can someone explain electric utility distribution easily?

[gettyu]

I’m working in an electric utility as a civil engineer. I don’t have a good background in electrical and think it would be helpful if I understood it better. I work on the structures but I’d like to be able to understand what’s happening when I’m invited to meetings.

Can someone provide a simple explanation on how power distribution works?

Is it actual amperage that gets distributed? Is it watts?

How does the amount of power vary between a 25kV primary and a 120/240V secondary?

Also why is it 120/240V and not just 120V? Or just 240V?

I have lots of questions, anything helps!

[Manon_Chaboud · Accepted solution]

Hello @gettyu, thank you very much for your question! 

Power distribution is the efficient and safe transfer of electrical power from its source to the end users. It begins with high-voltage transmission lines that carry electricity from power plants to substations.

At the substations, transformers lower the voltage to a safer level for distribution to homes and businesses.

Within power distribution, amperage (measured in amps) and power (measured in watts) are vital concepts. Amperage signifies the amount of electrical current in a circuit, while power (in watts) represents the actual energy used by devices.

Their relationship is defined by the formula: Power (in watts) = Voltage (in volts) x Current (in amps).

For instance, a 25 kV primary system, compared to a 120/240V secondary system, operates at a higher voltage, enabling efficient power transmission over long distances with lower energy losses.

On the other hand, the 120/240V secondary system is the standard voltage for residential and light commercial applications, providing suitable voltage levels for common household appliances and devices. The 120/240V designation indicates a split-phase system commonly used in residential settings. Here, 120V is used for standard outlets and lower-power devices, while 240V is used for larger appliances like electric stoves and dryers.

This split-phase design allows a wide range of electrical devices to be powered within a home without needing a completely separate wiring system for high-power appliances.