Generator Protective Relay 1

[harry152]

As you know for large size Generator #40 relay which is loss of field relay is actually a distance relay looking into the Gen. and in case of LOF the impedance seen by the realy will fall into the relay char. I need to know how I can make the relay to look into the Gen. Not on the load side.

 

[harry152]

PS: I have Generator computer model and model for distance relay working ok with power line but i need to know how I can hook up the relay to a generator.

 

[davidbeach]

Using CTs on the neutral end of the generator, the distance element will look through the generator, generator transformer, and out onto the system. Using CTs on the terminal end of the generator, the distance element can be set (directionality) to look from the terminals to the neutral of the generator, or out through the transformer to the line without seeing the generator.

If all you want to see is the generator itself, use the CTs on the terminals and look back into the generator. If you want to see both the generator and the transformer, use CTs on the neutral end.

 

[harry152]

Thanks David,

For the distance element you can set the directionality but how I can make my computer model directional? What elements do I need to consider to make it look only in the direction I want? The computer model is based on sensing current and voltage at the relay piont and using some digital techniques to calculate Resistance and Inductance, As I mentioned before it works ok with power line.

 

[davidbeach]

Not knowing anything about your computer model, I have no idea how to make it directional. My computer model experience is with programs that won't directly show the conditions that an impedance element would be looking at, but will provide enough of the system parameters to allow a hand calculation of the element settings. I would have to believe that there are software packages out there that can assist in setting impedance elements, I'm just not familiar with them.