#872 Haystack 4.0 General Questions

David Waterworth Wed 18 Nov 2020

I've been studying the chiller def. I like the addition of coolingCapacity, I couldn't find a corresponding electrical capacity though - I think that could be useful for anything that defines elec-input (i.e. the full load rating in W, kW etc.). Also, tags to represent the rated frequency and rated voltage would be useful (I only have amps and want to estimate the chiller power consumption so I use the 400V rating ie. P = sqrt(3) Vrated I). And perhaps manufacturer and model on the equip class.

Am I correct though being a tag it's not possible to infer the unit for phIoT:coolingCapacity ? The def indicates prefUnit of tonnes, BTU's or kWr but that doesn't help when you have an instance (phIoT:coolingCapacity 750 vs hIoT:coolingCapacity 213)? It seems like this should be an owl:Class rather than owl:DatatypeProperty in order to specify units like a point?

I noticed that the examples contain a custom tag - I cannot find the def for this at all though? Has this been deprecated? In the case below it seems to be used to define a compressor tag which is required but not part of the base ontology.

dis:"Alpha Waterside CH-1 Compressor Refrig Leaving Temp (CC)"

Are there any plans to add HLI's (High Level Interfaces)? I often find older chillers don't have efficiency sensor point so I have to calculate efficiency. Many newer chillers on the other hand don't either but they have an HLI which does. The HLI contains pretty much the same points as the chiller except it also contains calculated points such as COP. So far I've only seen HLI's with 1:1 relationship with the chiller so adding as a child equip might work.

And is there any way I can create a trio for my chws and validate it against Haystack 4.0 at the current time - i.e. I specifically need to model the compressors since they have the Amperage points I need to calculate COP. Knowing that compressor has to be added as custom is hard without validation.

Brian Frank Thu 19 Nov 2020

There is a move afoot to use first class point entities to model design/rated values like this instead of tags (owl:Class vs owl:DatatypeProperty). Hopefully there will be a formal proposal soon

David Waterworth Mon 23 Nov 2020

One thing I came across the other day is design/rated values as BACnet points as well.

Login or Signup to reply.