Not Enabling Instantaneous 50 Pickup 3

[Mbrooke]

I came across this in an IEEE presentation PPT. Is there any truth to this? Is someone really pushing a global mandate?

 

[davidbeach]

The ones we've looked at do happen to be current limiting. As I recall looking at them, they can coordinate, but not necessarily as tightly as one might be used to. Fitting one in between two T-rated fuses may not be possible, and the numerical value may need to be different that the numerical value of the T fuse. The cutout mounted recloser (TripSaver) is also big help in breaking up the number of fuses that need to coordinate in series.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[cranky108]

"what do you use for your primary and back in transmission, distribution and transformers?"
SEL-311, SEL-351S,SEL-751, SEL-387, SEL-487E. (I assume distribution transformers are X to 15kV).
We try to use the same backups that we use as primary. The backup concern is relay failure, and not relay design issues (like can happen on complicated schemes, or new relay designs).
The SEL 300 series is mature and robust, and less complicated than the newer relays.

The SEL-700 and SEL-400s series are some ones idea on saving some money. As a direct first cost, and the other as not needing so many relays, or CTs.
I understand the CT cost issue, we were short sighted in the past.
The others, I don't want to go into (I was overruled).

 

[Palletjack]

SEL-311, SEL-351S,SEL-751, SEL-387, SEL-487E. (I assume distribution transformers are X to 15kV).
We try to use the same backups that we use as primary. The backup concern is relay failure, and not relay design issues (like can happen on complicated schemes, or new relay designs).
The SEL 300 series is mature and robust, and less complicated than the newer relays.

The SEL-700 and SEL-400s series are some ones idea on saving some money. As a direct first cost, and the other as not needing so many relays, or CTs.
I understand the CT cost issue, we were short sighted in the past.
The others, I don't want to go into (I was overruled)

We use the 751A and 787 for our transformer (S&C)protection. One thing I like about the 787 is the math variables. I can add math variables and pull back metering on the 787, match it up to the 351R, then totalize the meters to get exact losses at each level and each circuit of distribution.

Actually found a couple of grow operations that way.. circuit showed an abnormal amount of losses for the month. Sent the service truck to ride the line out. He found an UG dip that definitely wasn’t ours.. had their own 225kVa XF in the house.
Yes.. IN the house

 

[Mbrooke]

@PalletJack: You rock! I had not idea you could do that with the 351R and 787- I will definitely look into this. And the grow op- LOL! Did they size the 225kva to the NEC, actual load or with future expansion in mind?

 

[Mbrooke]

@Cranky: Thanks. I personally would avoid the same model- Astoria showed us why we shouldn't do that- but to each their own.

 

[cranky108]

Since most of what I do is in the substation, I don't get to see what we are doing for the reclosers. I have used the 351R years ago. I like the logic ability.
I have not used the 787, as I started with the 587 and 387 relays.

We have not seen a grow where they used their own transformer. But we usually find them when they blow the transformer fuse (or it could be just a big hot tub).
Before grows I have seen a 200 amp meter melted by a grain dryer, so the meter limit is nothing new. But if the service runs more than the meter limit, we provide a free customer cut off to allow them to hire an expert to install the proper type of service.