Eli5: Why do you have to synchronize a generator in a complex process?

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Why can’t you just bring it to the desired rpm if you start it as motor and then slowly add torque to the shaft of the motor, so that the motor will turn into a generator and it will start to generate power.

In: Engineering

5 Answers

Anonymous 0 Comments

Generators don’t just push electrons down the wire like water down the hose, they cause electrons to move back and force roughly on a same spot, kind of like metalheads rocking back and forth ta metal show. When you wanna headbang at the show, you gotta be at sync with all the other headbangers. Same with generator, it needs to be in sync with all the other generators in order to contribute power to the grid

Anonymous 0 Comments

The big generators used on the grid that need to be synchronized are “synchronous generators”.

1) Synchronous generators will not general self-start if electricity is applied when they are stationary.

2) If a large generator is not synchronized and connected to the grid, there will be huge fluctuations in the amperage it is drawing and thus the forces (torque) inside the generator. This is likely to blow fuses or other electrical protection devices, and the fluctuating forces could conceivably cause physical damage to the generator (though I suspect the electrical protections are designed to kick in before mechanical damage would occur).

Anonymous 0 Comments

Synchronized generators are like two cars next to each other on the highway, driving at the same speed in the same direction. Connecting unsynchronized generators is like a head on collision.

If the generator and grid are the same frequency but out of phase, it’s like short circuiting both the grid and the generator, huge amounts of current flow and cause damage.

Anonymous 0 Comments

If you connect a standstill generator to a grid, it will experience massive startup currents. Those currents can easily burn power lines that lead into the generator, or even a part of a local grid. The generator will also experience a massive torque, that can tear it apart. The same will happen, if you plug a generator that is too much out of phase.

Of course, a generator and power lines could be designed to withstand those overloads. However, for big generators that are supposed to run 24/7 it is much cheaper to have a slightly more complex startup system, than a bigger power rating.

You can gently wind up a generator electrically, but for that you have to plug it into a lower voltage, and gradually step it up.

Anonymous 0 Comments

Because the power comes out of the generator in a wave, up and down. It hits the peaks of the waves in certain spots as the generator turns. Three different spots, to be exact, in three phase power in North America

The waves from the output of the generator need to match the waves already on the grid, otherwise they will physically interact and cause damage. The power coming in off-cycle from the grid will try to turn the generator into an electric motor, but it’s already spinning very fast. This conflict will physically destroy the generator