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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.
SIMATIC is a series of programmable logic controller and automation systems, developed by Siemens. Introduced in 1958, the series has gone through four major generations, the latest being the SIMATIC S7 generation. The series is intended for industrial automation and production. The name SIMATIC is a registered
Circuit breakers with higher ratings can have adjustable trip settings, allowing fewer standardized products to be used, adjusted to the applicable precise ratings when installed. For example, a circuit breaker with a 400 ampere frame size might have its over-current detection threshold set only 300 amperes where that rating is appropriate.
Selectivity, also known as circuit breaker discrimination, is the coordination of overcurrent protection devices so that a fault in the installation is cleared by the protection device located immediately upstream of the fault. The purpose of selectivity is to minimize the impact of a failure on the network.
About 2.2 million Siemens and Murray circuit breakers are being recalled over concerns a spring clip can break and cause the breakers to fail, the U.S. Consumer Product Safety Commission said.
Types used in commercial and industrial low-voltage distribution systems are rated to safely interrupt 200,000 amperes. The rating of power circuit breakers varies according to the application voltage; a circuit breaker that interrupts 50,000 amperes at 208 volts might be rated to interrupt only 10,000 amperes at 600 volts, for example.
Conversely, the 4000-series has "borrowed" from the 7400 series – such as the CD40193 and CD40161 being pin-for-pin functional replacements for 74C193 and 74C161. Older TTL parts made by manufacturers such as Signetics , Motorola , Mullard and Siemens may have different numeric prefix and numbering series entirely, such as in the European FJ ...
Lighting and power receptacle circuits in North American systems are typically radial from a distribution panel containing circuit breakers to protect each branch circuit. [8] The smallest branch circuit rating is 15 amperes, used for general purpose receptacles and lighting.