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In electrical engineering, IEC 60269 is a set of technical standards for low-voltage power fuses. [1] The standard is in four volumes, which describe general requirements, fuses for industrial and commercial applications, fuses for residential applications, and fuses to protect semiconductor devices.
Factor () Value Item 10 −19: 160 zA Current flow of one electron per second : 10 −12: 1-15 pA Range of currents associated with single ion channels [calcium (1 pA), sodium (10-14 pA), potassium (6 pA)] as measured by patch-clamp studies of biological membranes
Miniature circuit breakers and fuses may be rated to interrupt as little as 85 amperes and are intended for supplementary protection of equipment, not the primary protection of a building wiring system. In North American practice, approved general-purpose low-voltage fuses must interrupt at least 10,000 amperes.
The voltage rating of the fuse must be equal to or, greater than, what would become the open-circuit voltage. For example, a glass tube fuse rated at 32 volts would not reliably interrupt current from a voltage source of 120 or 230 V. If a 32 V fuse attempts to interrupt the 120 or 230 V source, an arc may result.
A suffix letter or number may be used with the device number; for example, suffix N is used if the device is connected to a Neutral wire (example: 59N in a relay is used for protection against Neutral Displacement); and suffixes X, Y, Z are used for auxiliary devices.
The utilization categories category for low-voltage switchgear defines the characteristic operating conditions for switchgear such as contactors, circuit-breakers, circuit-breaker-fuse units, contactor relays, etc. These devices are dimensioned for different electrical loads and for different operating conditions.
If heat is produced at a sufficient rate, the conductor temperature rises and the insulation can be damaged or ultimately the conductor itself can sag or melt. The ampacity rating for a conductor is based on the conductor diameter, material used (copper or aluminum), the rated maximum application temperature, and the installation conditions.
In electrical distribution, a fuse cutout or cut-out fuse (often referred to as a cutout) is a combination of a fuse and a switch, used in primary overhead feeder lines and taps to protect distribution transformers from current surges and overloads. An overcurrent caused by a fault in the transformer or customer circuit will cause the fuse to ...