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One-line diagram symbols...

One-line diagram symbols...

One-line diagram symbols...

In a one-line diagram, can you use a simple disconnect symbol to represent a circuit breaker?  Or do you use the typical circuit breaker symbol... the line broken with a little arched line over it?  I only ask because I am looking at the previous Engineers drawings and I am not sure if his one line diagram of our Plants High Voltage Distribution System is totally correct.  Here is an example of the symbols..  I know, kind of a dumb question...  



RE: One-line diagram symbols...

Typically, I would use the arched line to represent a circuit bkr with the numerical designation of 52 for an AC ckt bkr or 41 for a Field CB.
The simple disconnect symbol is usually used to represent a disconnect device, such as a 3 blade disconnect with device number of 8 or 89.

I'm sure that someone else will remember what the ANSI standard is for all the symbols

RE: One-line diagram symbols...

Thanks.  I thought so.

RE: One-line diagram symbols...

It is true, the latter symbol is used for Disconnector. However, it is also used for Circuit Breaker with a cross at the tip of the straight line portion. One more way of represnting the CB is with a small square.
In all the cases, the device no. for CB, that is, 52 is written adjacent to the symbol.

RE: One-line diagram symbols...

rrag's description matches mine: the boxed 52 device.  Also, for drawout [metalclad] MV gear, nested chevrons may be shown —>>—

One approach is to reserve the ‘arc’ symbol for LV AC{+DC} auxiliary station-power components.

RE: One-line diagram symbols...

There is no universal definition of electrical symbols used on SLDs, though there might be one in the future.
In general it is best to show a legend/key listing on the drawing of all the symbols used so there is never any confusion.

RE: One-line diagram symbols...

The arch symbol is North American (and sometimes British).  According to an old copy of "How to Read German Schematic Diagrams of Industrial Equipment" by Siemens, in Germany a Circuit Breaker would be like a blade disconnect (no extra x's, circles, or crosses) inside a rectangular box.

Perhaps someone more familiar with IEC symbols could comment.

For MV and HV circuit breakers, I would normally use a square box with either CB or a circuit breaker number inside.  If it were drawout, I would use -<<-   ->>-  on the leads.

RE: One-line diagram symbols...

may I add to wbd´s posting that 72 is the code for DC breaker

RE: One-line diagram symbols...

jghrist were did you get the copy of how to read german symbols do you have something you could email me. jholston@columbus.rr.com we have a machine with german schematics iam getting pretty good at figuring them out but a book of sorts or web page would be great.

RE: One-line diagram symbols...

My copy is from 1980 and is based on 1978 standards.  Not in electronic form, I'm afraid.  You might try asking a Siemens rep if they have an up-to-date version.  Also look at the "American & European Electrical Symbols" thread in the IEEE Code Issues forum.

German schematics are laid out for ease of manufacture I think.  We had a line-up of about 10 MV breakers and it took over 100 pages of schematics.  It is very difficult to get the whole picture and figure out how things will work.  Even the Brown Boveri field engineer on the project I was working on in 1980 said he made his own US style elementary diagrams to aid in field work.

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