IEEE 945-2019 pdf free download.IEEE Recommended Practice for Preferred Metric Units for Use in Electrical and Electronics Science and Technology.
1.1 Scope
This recommended practice provides the preferred metric units for use in Electrical and Electronics Science
and Technology and supports the application of IEEE/ASTM Si l0.
1.2 Purpose
The purpose of this recommended practice is to aid in the selection of appropriate metric units for
quanthies that arc of interest to electrical and electronic engineers.
2. Normative references
The following referenced documents are indispensable for the application of this document (i.e.. they must be understood and used, so each referenced document is cited in text and its relationship to this document is explained). For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments or corrigenda) applies.
IEEE/ASTM SI lOThI. American National Standard for Metric Practice.’ 2
3. Definitions
For the purposes of this document, the following terms and definitions apply. The IEEE Standards Dic,io,,arv Online should be consulted for terms not defined in this clause.
area density: The quantity of mass per area.
coefficient of heat transfer: The density of heat flow rate divided by the temperature difference. density: The quantity of mass per volume.
linear density: The quantity of mass per length.
mass concentration: The quantity of mass of a constituent per volume of the mixture. thermal insulance: The temperature difference divided by density of heat flow rate. thermal resistance: The temperature difference divided by heat flow rate.
NOTE -Coefficient of heat transfer and thermal insulance are reciprocals of each other.4
4. Multiples and submultiples of SI units
For SI prefixes, symbols, and multiplication factors, see IEEEJASTM SI 10.
A common practice is to use multiples and submuhiples that are a powers of io, also known as the rule of 1000.
5. Space and time
Table 1 provides preferred space and time SI units.IEEE 945-2019 pdf free download.