Efficiency with redundant single/three line diagrams

[SteveO NE]

As an engineer out on my own that never worked for a large firm, I sometimes find I've been missing some slick ways to make things be a bit more efficient.

Most of the work I do doesn't require separate redundant single line diagrams and three line diagrams - its either controls points or single line diagrams. However, a handful of financiers of some renewable projects want 3-lines and SLDs of the entire system which is redundant and adds no value in my viewpoint - its a balanced system and we already call out connection details where relevant, like say the SBJ, transformer connection diagrams, disconnect connection diagrams, so we are left with updating the 400 tweaks everyone inevitably wants to an otherwise simple drawing but now need to make sure we update the SLD and 3-phase diagram exactly the same each time. For some projects it is of course valuable but I mean we are talking about a couple of fused disconnects and an inverter, and everything is the same on all phases.

Is this normally done a different way to be able to just work from a single design and be able to maintain a SLD/3LD from a single design? Some viewport trickery with layers? Maybe it is what it is, and I just need to charge more, when someone wants this, but sometimes you don't know what you are missing until you are enlightened by someone who know which tool to use to do it. I am working in AutoCAD and/or BricsCAD so recommendations for either would work for me.

Thanks!

 

[JoeStillman]

A 3LD of an entire system is certainly redundant. Maybe you could get by with one typical 3-line for repetitive elements? In my work, which is general electrical construction in all types of buildings, we NEVER do a 3-line. We do, however, see them as part of the shop drawing submissions for a piece of switchgear or a generator.

This violates the principal I learned early on: "Only say it once!" Every time you repeat something, you multiply the possibility of disagreeing with yourself. You wind up making things less understandable instead of more complete.

Do the people that require 3-lines actually know how to read them?

 

[SteveO NE]

Maybe you could get by with one typical 3-line for repetitive elements?

This is exactly what we do unless forced to otherwise - we have detail drawings of how to wire the disconnect, or the transformer, or the inverters, etc. So sticking those components onto a drawing just to draw extra lines is a waste of time and again, exactly as you say, an opportunity to mess up. This latter point is why any time we are required to show the same thing on multiple pages its a single block or viewport that is guarantees its identical in every single place it appears because more than once you will forget to update one of them and cause a problem down the line.

Of course, lets not mention that electricians take and throw the page in the trash anyway because its just harder to read.

Do the people that require 3-lines actually know how to read them?

Most of the time its an out of touch engineer that works for an investor and feels like it makes things more engineery and official. They require it because they require it and cannot really answer the question of what value it adds.

Its nice to see I'm not alone thinking the requirement is just a terrible idea.

 

[petersonra]

We do three lines so when our shop wires it there is a place to mark on the drawing each wire as it is wired. Plus we make all the wire numbers unique and keyed to an index that is printed on the drawing. Then our QA inspectors can verify what was wired. Near impossible to do off a one line

We don't usually do one lines because generally there is no value to us to do one. But sometimes a customer wants one.

 

[ggunn]

I hear you loud and clear; occasionally an AHJ will require a TLD for a PV system for no apparent reason; a TLD is a pain to draw, it's hard to read, it makes the drawing far too busy, and it conveys no more information than does a SLD with grounding.

My AutoCAD template has a slew of completed SLDs and a few TLDs in model space that I can pull pieces from like tinkertoys from a toybox.

 

[MyCleveland]

I hear you loud and clear; occasionally an AHJ will require a TLD for a PV system for no apparent reason; a TLD is a pain to draw, it's hard to read, it makes the drawing far too busy, and it conveys no more information than does a SLD with grounding.

My AutoCAD template has a slew of completed SLDs and a few TLDs in model space that I can pull pieces from like tinkertoys from a toybox.

…toybox! I like that.
I am lost on most of the acronyms, guessing related to controls.
My design tool was similar. Separate dwg file that contained by voltage system every possible panel…mcb top, mcb bottom, mlo top, mlo bottom plus all the sub feed possibles in all bus sizes. Same thing for distribution panels, switchboards, metering, transformers, etc.
Everyone already had the inbound feeder sized…on the defpoints layer, so editing of some type was mandatory.
I looked at as going shopping when building a one-line, just copy over the parts, connect a few lines together and edit as needed.

 

[ggunn]

…toybox! I like that.
I am lost on most of the acronyms, guessing related to controls.

Sorry.
SLD = Single Line Drawing
TLD = Three Line Drawing

For virtually all the electrical drawings I generate, a TLD is unnecessary and a waste of time and effort.

 

[kingpb]

I have worked for a lot of large firms, that did large power projects. What you are describing is very typical for a large project. You will need SLD's that show quite a bit of detail that are needed to convey the equipment required so the suppliers can bid on it; along with a detailed specification. The main switchgear SLD will also need to be provided to the utility for the interconnection application. The manufacturer, as part of their submittal package will, or should, be required to provide detailed three -line diagrams. These will be used for multiple purposes, but mainly for power wiring and relay protection. Why you will probably have to create them is that by the time the manufacturer supplies them you will have proceeded along with your design to where you need them. Additionally, you will have wiring that is done in the field that the manufacturer isn't responsible for, and you have to have a complete set of wiring diagrams. You might, and I say might, be able to get the manufacturer to supply their drawings in CAD, and thus be able to use them in lieu of creating your own, but often, like I said earlier, need the info for the design prior to receiving them. Yes, it will feel like extra work, but your fee should account for it. You also need a TLD to create a phasing diagram.

 

[SteveO NE]

I have worked for a lot of large firms, that did large power projects. What you are describing is very typical for a large project. You will need SLD's that show quite a bit of detail that are needed to convey the equipment required so the suppliers can bid on it; along with a detailed specification. The main switchgear SLD will also need to be provided to the utility for the interconnection application. The manufacturer, as part of their submittal package will, or should, be required to provide detailed three -line diagrams. These will be used for multiple purposes, but mainly for power wiring and relay protection. Why you will probably have to create them is that by the time the manufacturer supplies them you will have proceeded along with your design to where you need them. Additionally, you will have wiring that is done in the field that the manufacturer isn't responsible for, and you have to have a complete set of wiring diagrams. You might, and I say might, be able to get the manufacturer to supply their drawings in CAD, and thus be able to use them in lieu of creating your own, but often, like I said earlier, need the info for the design prior to receiving them. Yes, it will feel like extra work, but your fee should account for it. You also need a TLD to create a phasing diagram.

Right but if I am reading what you are saying correctly this isn't a redundant diagram you suggest- I mentioned doing controls and points, for instance, as a detailed specification - For instance SLD shows a line between a protective relay and the main switch gear and has a callout that says see E 2xx for detailed wiring specification, the SLD give the global view what is happening and detailed TLDs or points diagrams show the detail needed to not guess, if I change my points on my detailed view, I generally am still not conflicting with myself if I forget to change it on the SLD. An SLD high level view vs detailed wiring diagrams are two different things.

Repeating oneself on an inverter based system where there ABC/N literally are just 4 lines on a paper vs 1. We have wiring diagrams of the inverter and the transformers with phasing, why take up space and ink to show that there are in fact 4 conductors (we always show grounding/bonding separate so I'm intentionally excluding that on my counts), when anyone qualified to do that system knows that its a 3 phase inverter and it requires 4 conductors (keep in mind that there is a note that the inverter is configured as say 3 phase 4 wire, 3 phase delta, etc.).

Also large projects are a different beast with different scales of economy built in. We do 20MW projects and provide much more detailed packages and more eyes on them, big projects have more times to screw up that someone wont see or catch. When an investor wants a 30 page package for a 250kW project and wants it done in 2 weeks, and wants you to be competitive with pricing, then they shouldn't be asking for details that aren't needed. It would be cheaper and faster for me to do site visits or spend an hour with the electrician making sure they understand what they are doing than to provide a ridiculous level of detail, especially when there is no value added to that detail. Small projects are easier to catch and correct mistakes, they also usually have electrical teams of lower skill level at reading complex prints which needs to be factored in. I would argue our designs are more detailed for these smaller projects in some senses where my designs are more schematics with depictions of gear. In order to fit more detail in a global three line, one would have to sacrifice on those schematic style drawings and move on to symbols for components.