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Graphical symbol for Normally Open Held Closed limit switch

Graphical symbol for Normally Open Held Closed limit switch

Graphical symbol for Normally Open Held Closed limit switch

I'm currently trying to hold my ground over the symbolic representation of a Normally Closed Held Open switch with an engineer. He pretends my representation is not per ISA 5.1. As far as I can see from the internet, I do not see a representation of such a switch at all according to this standard... unless I'm missing something.

I found lots of examples suggesting I'm right with the way I represent it, but he keeps on refuting that.

So I'm asking here if somebody would be kind enough to share with me the correct way of representing a NCHO switch, and per which set of standard.

Note: the engineer is a consulting engineer, in a different location, and won't share with me his standard document, he is only refering to "ISA 5.1".


RE: Graphical symbol for Normally Open Held Closed limit switch

Here is a partial page from ISA 5.1 2009 with electrical symbols. It does not illustrate the held closed/open versions.
Items 10 through 15 are actuation symbols: rotary (manual), pressure, Differential pressure, liquid level, temperature, flow.

And here is a 'motor controls' graphic showing the same symbols and the corresponding held open/closed versions:

RE: Graphical symbol for Normally Open Held Closed limit switch

Thank you Danw2.
I had already seen this and provided similar links to that engineer, to no avail. The way the NCHO is represented is how I did it, but that person wants it as a NC contact, the way they are asking, but they call it NCHO. Go figure... In RED in the attached, you can sse his comments.

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