No, the transformers don´t have independent circuit breakers, I need the 67 relays in order to protect the area between the 1½ substation breakers and the HV CT on the transformer diferential protection.
jbartos:
As I first thought, I´m planing on a 67 directional overcurrent relay with a time dfinite curve. So, the 21 relays (2nd zone relay)on the far terminals should be set at 0.6 sec., the 67 relay at 0.3 sec. and of course the transformer differential relay instantaneous.
What I wanted was...
We designed a 1½ substation in a 230 MW Power Plant. It has three line outputs and three transformer inputs from the power plant. Due to budget restrictions each of the transformer inputs have two transformers instead of one and they are not in paralel. Each transformer have three generating...
Mr hmchi:
We have in paralell operation 2X150 MVA, 3X 100 MVA 230/138 KV transformers with high voltage OLTC and we haven't had any troubles, we also have 2X25 MVA, 2X50 MVA 138/13.8 KV with OLTC on the secondary sides and we we haven't had any troubles either...
As for the short circuit...
Mr./Mrs hmchi:
our stepdown transformers are connected in parallel (Honduras Interconnected System, Central America)and they normally have On Load Tap Changers (OLTC). You can have two kind of controls for the OLTC, one that tries to have the same tap (no more than one tap of difference) on both...
Pablo02:
I agree with what you added, I come from a different background so we've had some special problems, I would like to add the following comments:
1) Underfrecuency relays and load shedding: If there's not
somebody who is supervising the settings and the circuits
to be disconnected...
To 144X:
I agree with most of the arguments here, stranded wire is easy to install, you don't have to worry about the bends where you can break a solid wire and its easy in your fingers when you install it.
But all of that is not the point...When you're checking for a faulty wiring in an old...
Sidiropoulos:
I agree with you, while it's not about the T&D, I have judt received the Bassler catalog and it has some very interesting articles on generator protection and exciters, since they haven't updated the sentinel books I recommend this catalogue to you
I have the T&D book, the applied relaying book and the distribution book and they are the "bibles" on their fields.
So I recommend anybody to buy them.
If anybody have seen the new versions of this books, I would like to know if they have upgraded them, since the only problem is that...
I've never had a syncrocheck relay blown in any installation I've commissioned, with the exception of one that we burned in a new installation because it was wrongly wired.
Please check the wiring and/or if this equipment utility graded as was recommended.
Please advice when you find the problem...
Normally, when you have a delta distribution system, you usually grounded through a zizg zag transformer.
The transformer provides a path to ground for any ground fault in the system; allowing the ground relay to trip for this fault, otherwise the relays will operate until you have a double...
You can install the generator directly to the 12 KV feeder, but first you have to check the fault current on the location with your generator added.
If you're worried by the impact of the line to ground faults on the feeder, ground the generator trough an impedance.
You have to hire a consultor for your project, but if you are still in the satage where you´re still not sure if your project will give returns enough to hire a consultor, you have to check the local legislation in order to know if you're going to get special prices, etc. ( in my country we do)...
