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Insulation system. The electrical insulation system for wires used in generators, electric motors, transformers, and other wire-wound electrical components is divided into different classes by temperature and temperature rise. The electrical insulation system is sometimes referred to as insulation class or thermal classification.
A Class 150-2 Hour vault must keep the temperature below 150 °F. for at least two hours, with temperatures up to 2,000 °F. (1,093.3 °C) outside the vault. Class 350 Rating. This rating is the requirement for protecting paper documents. Above 350 °F (176.7 °C) paper is distorted by the heat and information is lost. A Class 350-4 Hour vault ...
In electrical and safety engineering, hazardous locations (HazLoc, pronounced haz·lōk) are places where fire or explosion hazards may exist. Sources of such hazards include gases, vapors, dust, fibers, and flyings, which are combustible or flammable. Electrical equipment installed in such locations can provide an ignition source, due to ...
Power amplifier classes. In electronics, power amplifier classes are letter symbols applied to different power amplifier types. The class gives a broad indication of an amplifier 's characteristics and performance. The first three classes are related to the time period that the active amplifier device is passing current, expressed as a fraction ...
Thermistor. A thermistor is a semiconductor type of resistor whose resistance is strongly dependent on temperature, more so than in standard resistors. The word thermistor is a portmanteau of thermal and resistor . Thermistors are categorized based on their conduction models. Negative-temperature-coefficient (NTC) thermistors have less ...
In the USSR, per GOST 2582-72 with class N insulation, the maximum temperatures allowed for DC motors were 160 °C for the armature, 180 °C for the stator, and 105 °C for the collector. The one-hour rating is typically about 10% higher than the continuous rating and is limited by the temperature rise in the motor.
Fuse (electrical) A miniature time-delay 250 V fuse that will interrupt a 0.3 A current at after 100 s, or a 15 A current in 0.1 s. 32 mm (1 1/4") long. In electronics and electrical engineering, a fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Its essential component is a metal ...
Each type specifies characteristics of an enclosure, but not, for example, a specific enclosure size. Note that higher numbers do not include the lower-numbered tests. For example, types 3, 4 and 6 are intended for outdoor use, but type 5 is not. A NEMA enclosure rating does not mean that it also meets the same UL enclosure rating.