1759   Add units rpm and bar

Created: 25 Feb 2021

Status: Future Improvement

Part: Part 7-3 (2020; Edition 2.1)

Links:

Page: 125

Clause: 8.16

Paragraph: Table 112

Issue

IEC 61400-25 requires addition of units rpm and bar

Proposal

CD distributed in TC88 February 2021 includes dataobjects requing unit bar and rpm.

Discussion Created Status
Future 25 Oct 22 Future Improvement
Will be addressed as future improvement.
As long as not avaialbe, we recommend to use the SI units, and take care of the conversion to Pa and to rpm at the HMI level. 		11 Oct 22 Approval (Future Improvement)
I agree with Hubert's comment:
Proliferation of non SI-units shall be avoided. RPM can be used for user interface, but not for technical transmissions. Same for non-SI units like kWh. Meteorological data are given in hPa or millibar.

I recommend therefore the
- introduction of a multiplier literal for 5 - L or lakh and usage of Pa for the pressure,
- the usage of 53 rotations per second for the velocity. 		02 Aug 22 Discussion (red)
TISSUE resolution is open for discussion 06 Dec 21 Discussion (red)
The problem is, that the enumeration with multiplier 5 does not exist. So we would need an extension of table 104 with the enumerations 30 Aug 21 Accepted
For bar versus Pascal: we can use 39 with multiplier 5 20 Jul 21 Triage
What is the issue if a client shall convert the unit from SI-unit to a Non-SI-unit?
Non-SI-units in data exchange shall be avoided.
I think there is a risk of misunderpretations if the transmitted value can be configured with different units.

14 Jun 21 Triage
Proliferation of non SI-units shall be avoided. RPM can be used for user interface, but not for technical transmissions. Same for non-SI units like kWh. Meteorological data are given in hPa or millibar. 13 Jun 21 Triage
Rotor speed per second will have one or more decimal when applied in wind domain to the speed of a wind turbines rotors, and hence this unit is not in use. All known implementations use revolutions per minute rpm.

Although it is recognised that Pascal is derived base unit in SI-system it is general practice in wind domain to provide pressure in bars. Conversion possibility is not in place in most clients. (1 bar = 100 kPa).

Just as ms in some data attributes we see need for wind domain to support rpm and bar in parallel to "rps" and bars in parallel to Pasclas. This is used in multiple data objects of CVD MV. Is there any alternative way to define data objects for pressure using bars? 		10 Jun 21 Triage
Need feedback from proposer if suggested existing units 53 and 39 can be used. 03 Jun 21 Triage
unit 53=rotations per second and 39=pressure in pascals.
these existing values should suffice. 		25 Feb 21 Triage

 

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