In electronics, derating is the operation of a device at less than its rated maximum capability to prolong its life. Typical examples include operations below the maximum power rating, current rating, or voltage rating.
Power semiconductor devices have a maximum power dissipation rating usually quoted at a case temperature of 25 °C (77 °F). The datasheet for the device also includes a derating curve which indicates how much a device will dissipate without getting damaged at any given case temperature, and this must be taken into account while designing a system.
As can be seen from the derating curve image for a hypothetical bipolar junction transistor, the device (rated for 100 W at 25 °C (77 °F)) cannot be expected to dissipate anything more than about 40 W if the ambient temperature is such that the temperature at which the device's case will stabilize (after heat-sinking) is 65 °C (149 °F). This final case temperature is a function of the thermal resistance between the device's case and the heat-sink; and the heat-sink and the ambient (this includes the heat-sinks temp/watt rating - with lower values implying better cooling characteristics).
Some capacitors' voltage capability is reduced at higher temperatures because the softened dielectric (e.g., a polymer) is softened further by the heat, and its breakdown field strength is reduced. Derating curves are included in data sheets for such capacitors.
Derating can also provide a safety margin for transient voltages or currents (spikes) that exceed normal operation or prolong life. For example, the life of electrolytic capacitors is dramatically increased by operating them below their maximum temperature rating.
In electrical installationsedit
All dimmers rely on heat conduction and convection to keep the electronic components cool. Similarly, power wiring (e.g., house wiring) not surrounded by an air space (e.g., inside a conduit) needs to have its current-limiting device (e.g., circuit breaker or fuse) adjusted so as not to carry as much current through that circuit. Derating is the reduction of the maximum capacity (load) a unit can reliably handle when fins/side sections are removed.
See alsoedit
Look up derate, derating, or derated in Wiktionary, the free dictionary.
"Complementary NPN−PNP Power Bipolar Transistors" (pdf). Datasheet. OnSemi. MJL0281A.
April 09, 2024
derating, this, article, about, electronics, adjustment, engines, longer, engine, life, engine, tuning, this, article, includes, list, references, related, reading, external, links, sources, remain, unclear, because, lacks, inline, citations, please, help, imp. This article is about electronics For the adjustment of engines for longer engine life see Engine tuning This article includes a list of references related reading or external links but its sources remain unclear because it lacks inline citations Please help improve this article by introducing more precise citations October 2014 Learn how and when to remove this template message In electronics derating is the operation of a device at less than its rated maximum capability to prolong its life Typical examples include operations below the maximum power rating current rating or voltage rating Contents 1 In electronics 2 In electrical installations 3 See also 4 ReferencesIn electronics edit nbsp Derating curve of a hypothetical power device Power semiconductor devices have a maximum power dissipation rating usually quoted at a case temperature of 25 C 77 F The datasheet for the device also includes a derating curve which indicates how much a device will dissipate without getting damaged at any given case temperature and this must be taken into account while designing a system As can be seen from the derating curve image for a hypothetical bipolar junction transistor the device rated for 100 W at 25 C 77 F cannot be expected to dissipate anything more than about 40 W if the ambient temperature is such that the temperature at which the device s case will stabilize after heat sinking is 65 C 149 F This final case temperature is a function of the thermal resistance between the device s case and the heat sink and the heat sink and the ambient this includes the heat sinks temp watt rating with lower values implying better cooling characteristics Some capacitors voltage capability is reduced at higher temperatures because the softened dielectric e g a polymer is softened further by the heat and its breakdown field strength is reduced Derating curves are included in data sheets for such capacitors Derating can also provide a safety margin for transient voltages or currents spikes that exceed normal operation or prolong life For example the life of electrolytic capacitors is dramatically increased by operating them below their maximum temperature rating In electrical installations editAll dimmers rely on heat conduction and convection to keep the electronic components cool Similarly power wiring e g house wiring not surrounded by an air space e g inside a conduit needs to have its current limiting device e g circuit breaker or fuse adjusted so as not to carry as much current through that circuit Derating is the reduction of the maximum capacity load a unit can reliably handle when fins side sections are removed See also edit nbsp Look up derate derating or derated in Wiktionary the free dictionary Safe operating area UnderclockingReferences edit Complementary NPN PNP Power Bipolar Transistors pdf Datasheet OnSemi MJL0281A Retrieved from https en wikipedia org w index php title Derating amp oldid 1144020449, wikipedia, wiki, book, books, library,
