Neutral grounding ot 3 phase generator 1

[Shamas javeed]

Good evening everyone

Dear I have a genset connected with hydel turbine having terminal voltage 380v and 860kw capacity.
The neutral (star point) is not connected to the ground.
What should I do to connect the neutral to the ground??
Ngr?
Magnetic contractor ?
Direct grounding??
I will be thankful
Regards

 

[waross]

If you have line to neutral loads then ground the neutral directly.
Otherwise you have a choice between direct grounding, and NGR grounding.
A contactor, NO.
Exception. A contactor and a second NGR may be used to build a "Thumper" circuit.
The main NGR ramains permanently connected.
When the thumper circuit is energized it connects and disconnects a second NGR on a short cycle.
Possibly 5 seconds on and 5 seconds off.
The ground fault current will change accordingly and the fault may be located by following the pulsing fault current with a clamp type Ammeter.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Shamas javeed]

Good morning waross
The load is not directly connected to the neural (380v) it is feeding the 11 kv star delta transformer

Regards

 

[Shamas javeed]

Good morning waross
And what if we have a mix load mean internal on phase to ground 220v for auxilary load and 11 kv for line star delta
Thanking you

 

[waross]

Grounding the neutral is a matter of codes and regulations.
Regulations are not always the same in various parts of the world.
What is the law in one area may not be common practice in another area.
I work in Canada where the code is very similar to the code in the USA.
For a generator of that size I would generally ground the neutral, solidly.
There is then no problem with line to neutral loads.

That said, and if there are no line to neutral loads, it is allowable to ground through a resistance if equipment is included to detect and alarm ground faults.

It is also acceptable to ground the neutral through a resistance with line to neutral loads if the system is disconnected automatically in the event of a ground fault and a few other conditions.

For a generator that size I would tend to solidly ground the neutral.
If the customer wanted resistance grounding I would use resistance grounding.
What code do you work under?
This information may not be valid in your jurisdiction.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Shamas javeed]

Dear I have a chanies machine and they have different standards according to terminal voltage
Mean to say @400 v terminal voltage they use contractor to ground the neutral
Higher than that 6.6 kv NGR is used.
Here I am on a site where the softwhere of avr card flash out over external fault on investigation I got to know that the neutral is not grounded and eirthing is not proper
Now I want to ground the neutral that's why I am asking
Now sujest me what should i do?
Regards
Shamas

 

[waross]

I have grounded the neutral on every machine that I have installed.
If the machine is working through a transfer switch or if it works in parallel with other generators the ground is often placed in the main panel and a neutral conductor run to the neutral of each generator.
For a single generator the neutral is generally bonded to ground at the generator.
Is this a single generator or are there other generators working with it?


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Shamas javeed]

Two generators having 380v terminal voltage sink together at 11 kv bus after step up transformer how should I do the grounding?