Oil & Gas Network protection system

[saberetap]

We have a 5.5kV network in our offshore plateform. I do all electrical simulation with ETAP 7.5 Software. I have some questions:
- We have 4 generators in service with relay protection. And in each generator incomer we have another relay. In case of fault between generator and 5.5kV busbar I opte to use ANSI 67 function to isolate faulted incomer. ANSI 50 can be desactivated or no. Also for setting, I chose In and the time delay (0.15s) that allow it to trip before the ANSI 50 of other incomers trip (2s)..
- In ETAP software, to allow the two function 50 and 67 I must use two separate relays!!
- Setting of 59N and 67N for isolated neutral system.


NB: we have 2 generators of 5MW and 2 generators of 2.5MW.

Thanks for your help

[Rudi Tua]

Hi Saberetap,

It is not easy for me to understand your question, but hope this can help
1. ANSI 50 you mean instant OC?, yes of course, as far as the coordination is perfect
2. The time delay 0.15s is not ANSI 50 behavior, please use 51 if you want to add any delays more than milli second, especially (for me) about 2 second delay is suicide for the generator or other electrical equipment.
3. About function 50 and 67, it depends on the relay type you use, if you choose the digital relays (exp. GE UR relay) than you can use only 1 relay onboard and also in ETAP file
4. Setting 59 and 67 ... well, setting for me is an "art", once again, depends on the system itself and the art of the engineer. eventhough there is some rule of thumb for it.

Hope that help you.
Thanks

[angki]

Dear Rudi Tua,

I have similiar problem between powerline and pipeline. The problem is, powerline 20 kV will buried in 150 m deep, our pipeline is 160 m deep. The HV plan will put on side pipeline as far 30 cm. From contractor powerline said, they using cable with code name NYFGbY three phase. After I read datasheet about NYFGbY, no spesification about magnetic field around that cable.

If that powerline operated soon, does it interference cathodic protection on pipeline?

What standart (API, ASME, NACE etc) discuss about this?

Thanks.

Hi Saberetap,

It is not easy for me to understand your question, but hope this can help
1. ANSI 50 you mean instant OC?, yes of course, as far as the coordination is perfect
2. The time delay 0.15s is not ANSI 50 behavior, please use 51 if you want to add any delays more than milli second, especially (for me) about 2 second delay is suicide for the generator or other electrical equipment.
3. About function 50 and 67, it depends on the relay type you use, if you choose the digital relays (exp. GE UR relay) than you can use only 1 relay onboard and also in ETAP file
4. Setting 59 and 67 ... well, setting for me is an "art", once again, depends on the system itself and the art of the engineer. eventhough there is some rule of thumb for it.

Hope that help you.
Thanks