Connecting a synchronous generator to the grid

Click For Summary

Discussion Overview

The discussion revolves around the process of connecting a synchronous generator to the electrical grid, specifically focusing on the requirements for circuit breakers and determining the appropriate cable cross-section for the connection. The context includes a college project involving a 400 V, 640 A, 440 kVA generator and its integration into a local grid system.

Discussion Character

  • Technical explanation
  • Homework-related
  • Debate/contested

Main Points Raised

  • One participant inquires about the method to determine the cable diameter needed for connecting the generator to the grid using two circuit breakers.
  • Another participant emphasizes the importance of coordinating with the local electrical utility, noting that they have specific rules and will inspect the installation.
  • A participant clarifies that the project involves connecting the generator to a college network operating at 50 Hz, 3 phases, and expresses uncertainty about the cable diameter determination.
  • There is a question regarding whether the generator came with electrical cables attached and what type of device is driving the generator, suggesting that the same thickness conductors as those used for the motor might be applicable.
  • One participant warns that the maximum current through the cables is influenced by the protection settings on the circuit breakers, cautioning against assuming the maximum current is solely based on the generator's data plate.

Areas of Agreement / Disagreement

Participants express various viewpoints on the connection process, with no consensus reached regarding the specific methods for determining cable size or the implications of current ratings and protection settings.

Contextual Notes

Participants mention the need for relevant standards and the potential variability in current due to protection settings, indicating that assumptions about maximum current based solely on the generator's specifications may not be valid.

braneCRO
Messages
2
Reaction score
0
Hi for a project i need to connect a synchronous generator to the electrical grid, i need to use 2 curcuit breakers and . How to determine the cross section of the cables required and how to connect them to the 2 curcuit breakers.
 
Physics news on Phys.org
braneCRO said:
Hi for a project i need to connect a synchronous generator to the electrical grid, i need to use 2 curcuit breakers and . How to determine the cross section of the cables required and how to connect them to the 2 curcuit breakers.

Welcome to the PF.

What kind of project is this? Who is the electrical utility in your area? Any connection to the grid will be coordinated by that utility, and they have a number of rules that you need to abide by. They will inspect your installation before giving you the go-ahead to make the first connection.
 
It’s a college project, I am connecting the generator to the college network (50 Hz, 3 phases), the generator is 400 V, 640 A and 440 kVA. My assignment is to connect it to the local grid using 2 circuit breakers (one for the automatic synchronization device and the other for the main connection to the bus. I don t know how to determine the cable diameter…
 
Did the generator not come with electrical cables attached? It's a generator, so you have something driving it--a large diesel engine, or a powerful 3-phase motor? The generator is 400 volts, 3 phase. Is the college power also 400 volts? I reckon you should be able to use the same thickness conductors as are used for the motor, if you can get hold of more of them.

I've forgotten almost all my motor theory. But I think it's probably true that just because the generator is rated for 640 amps, it does not follow that you will necessarily operate it so that it does supply that amount of current.

You say two circuit breakers. Do you mean two sets of triple circuit breakers?
 
The size of a cable depends on the maximum current that is going to pass through it there should be copies of the relevant standards in your college library. The max current that passes through the cables will depend on the protection settings on your breakers, do not be fooled into thinking that the max current is limited by what's on the data plate if you get a high leading or lagging current you can turn a generator into a pool of mo;ten copper very quickly, Go and start researching protection settings.
 

Similar threads

Synchronous generator variable speed and constant excitation
  • · Replies 3 ·
Replies
3
Views
2K
Self excited induction generators and grid connected solar inverters?
  • · Replies 9 ·
Replies
9
Views
2K
2 Synchronous Generators in parallel connection
  • · Replies 4 ·
Replies
4
Views
2K
Synchronous generator on an infinite bus
  • · Replies 37 ·
2
Replies
37
Views
8K
Engineering Synchronous motor coupled to a DC Compound Motor Problem
  • · Replies 2 ·
Replies
2
Views
3K
Synchronous machine problem (not homework)
  • · Replies 2 ·
Replies
2
Views
2K
AC generator output voltage to grid question
  • · Replies 4 ·
Replies
4
Views
3K
Static B.C & first moment of area of connecting rod
  • · Replies 4 ·
Replies
4
Views
2K
Power grid & generator questions
  • · Replies 46 ·
2
Replies
46
Views
7K
Engineering How Do You Calculate Current and Power Factor in a Synchronous Induction Motor?
  • · Replies 4 ·
Replies
4
Views
4K