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Switching under load


Corné

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Good morning everyone

I have questions purely for the sake of interest. Lets say the whole municipality is load shed:

1) How is the power switched on and off? Is there like a main MAIN circuit breaker that someone goes and switch on and off?

2) Does someone physically have to go and drive somewhere to throw the switch or is it done electronically/remotely?

3) And lastly, how does the circuit breaker (if such a thing is even used) switch such a large load? Wouldn't it arc leading to "strange" voltages similar to power dips when a kettle or AC is switched on (inrush current?)?

Thank you in advance for entertaining my silly questions?

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You can youtube this stuff. They use air circuit breakers, big ones to open and close the system at the transfer-station. Now days this is been control by computers and a central system where someone sits and keeping a eye on the grid. My one friend dad is certified who needs to go to this places when they install this stuff and he needs to test and sign off then.  

Some guys will give more info. 

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2 hours ago, Corné said:

Good morning everyone

I have questions purely for the sake of interest. Lets say the whole municipality is load shed:

1) How is the power switched on and off? Is there like a main MAIN circuit breaker that someone goes and switch on and off?

2) Does someone physically have to go and drive somewhere to throw the switch or is it done electronically/remotely?

3) And lastly, how does the circuit breaker (if such a thing is even used) switch such a large load? Wouldn't it arc leading to "strange" voltages similar to power dips when a kettle or AC is switched on (inrush current?)?

Thank you in advance for entertaining my silly questions?

1) Yes, most larger places are at least ring fed, so at least 2 CB's, but only 1 if you're on a radial feed.

2) Can be done both ways and without intervention, by protection relays in case of a fault.

3)The circuit breakers (CB's) are designed to break fault current, load current is small potatoes. This is known as "tripping".There are various arc quenching techniques, oil and air blast was used in the past. Arcing will stop at zero current crossing. Grading capacitors to evenly spread the voltage are used when the CB has multiple breaks.

Nowadays SF6 gas is mostly used as the arc quenching medium, with point of wave switching being used on reactors and cap banks.

 

Edited by phil.g00
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