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In practice maybe. Technically I don't think there is a provision in C57.13 that requires accuracy above the standard burden though. What does the CT manufacturer documentation say?

I'd try contacting Leeco.

Its easy to use. Common for non CAD folks to collaborate as multiple people can markup the same PDF simultaneously. Comes with lots of PDF tools as well, merging/splitting, measuring etc. If you know CAD already you may find it limiting.

https://assets.lutron.com/a/documents/controlling%20leds%20webinar.pdf You could try calling Lutron. I have linked a webinar on LED lighting from them. It briefly discusses dimming.

It "flows" in phase and equal magnitude through all the sequence networks. I1=I2=I0 The current does not flow equally through all the phases (A,B,C)

A video from CNC Kitchen on YouTube also comes to mind. He was attempting to print translucents as clear as possible. I believe it resulted in very strong layer adhesion. The technique may work here. Can't remember exactly what parameters he used, maybe slower and hotter. I'll see if I can...

Have you tried chemical smoothing? Not sure if it would work but may be worth a shot. Or leave it hollow and fill with epoxy. I believe there is an infill pattern that would allow an epoxy fill in between walls.

Yes, the 3I0 value would be used to set your ground relays. Could also be used in ground grid studies, ground potential rise calculations, etc.

Only seen one open circuited for a brief moment. C800s are pretty good at letting you know they are open. (Terminal blocks inside control house melted together) No known permanent damage to the CTs. Tested okay afterwards. I've heard of smaller CTs being left open for a long period of time...

Edit. Didn't see this was in mechanical.

How about a Variac in between your voltage source and the 230V input of the 230/12 transformer? Then an ammeter on the low side of the 230/12V transformer so you can dial in the current.

What relaying function is it performing? Is it redundant? I don't recall any inadvertent operations due to a settings change on a relay. I still prefer to have them isolated or out of service for settings changes though. That way you can test the changes, and make sure you got everything...

A REL-316? Is it redundant? If it is redundant, I would just cut it out prior to making your changes.

It's not possible to accurately gauge the strength of the short circuit. You would need to talk to the utility that owns the line. I'm not a lineman so I won't comment too much on the required outage time but the damage doesn't sound too bad so likely less than one day. Was the metal structure...

I have never heard of a 2.5A nominal CT. Are you sure you don't have a 5000:5 CT? It's the same ratio as 2500:2.5 Two 5000:5 A CTs with 2500A primary in each phase with a SERIES connection will result in 2.5A flowing in the secondary. (With half the voltage across each CT compared to a single...

Are you sure your CT secondaries are in series and not in parallel?

Do you have the latest firmware? I'd check that first. I haven't worked with ABBs in a long time and never with that particular relay but the logic should be customizable, at least the 670 series was. Can't remember if it's done in PCM600 though or different software.

@Cranky108 Everything is run in conduit and I'm not aware of any ground conductor ran along side (or in) the conduit. If both ends of the shield were to be grounded there would still be continuity to the ground grid on each end. That is not quite the same as what is recommended though.

The ground grid was re-studied not too long ago. The soil resistivity was averaged around 600 ohm-meters but was tested when the ground was wet. I'd love to just ground the shields at both ends but the portion in IEEE 525 about using a ground conductor parallel to the shielded cable makes me...

Yes, its possible. I have no experience with the 7UT86. In general, with parallel CTs on differentials you need to be careful as the restraint function may not work as well compared to individual CTs. If you had say 10,000A of fault current flowing into one breaker and out the other...