1403   Unit for percent

Created: 06 Jun 2015

Status: In Force (green)

Part: Part 7-3 (2010; Edition 2)


Page: 168

Clause: Annex E


Category: Issue for edition 2 of this part


Following the latest TC57 WG10 Regina meeting, and the assessment of the requirement to support the coming 90-3 TR, it appears that the current rule to express "percent" as dimensionless with multiplier -2, may be mathematically true, but physically wrong in the sense that percent rate can't be expressed as Hz (1/s) with multiplier -2.
It shall also be noticed that ppm (percent = 10000 ppm) is treated as a unit.


Creating percent as a unit, will enable to create percent rate unit as "percent/s".
This would lead to have consistent treatment for percent and ppm.
This proposal doesn't break compatibility however the precedent rule for percent (dimensionless with multiplier -2) should be deprecated.

Discussion Created Status
22 Nov 15 In Force (green)
to be applied to Ed 2.1
Final Proposal
Add unit percent/s as unit 87
21 Oct 15 Ballot Period
Note that the unit 'dimensionless' with multiplier -6 is equivalent to 'ppm'. I suggest to use the special ppm unit only for quantities typically provided in this unit. 09 Jun 15 Discussion (red)
if a unit for percent/s is required, it can be added.
However, the representation of percent value should remain as defined in current part 7-3.
As the calculation method "rate" has been deprecated from 7-4, there is also no need to "enable to create percent rate unit".
Proposal add "%/s"
08 Jun 15 Discussion (red)
Percent is dimensionless, it cannot be treated as a unit.
Percent should always be associated with the unit it is related to,
e.g. %relative humidity, %stateofcharge, %reliability
Therefore, % should only be present as a suffix, but not as a unit.
07 Jun 15 Triage


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