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The short-circuit current should be around 20 times the rating of the circuit to ensure the branch circuit protection clears a fault quickly. Quick disconnecting is needed, because during a line-to-ground short circuit the grounding pin potential on the power outlet can rise relative to the local earth (concrete floor, water pipe etc.) to a ...
Bolted fault current in the range of 700–106,000 A. Grounded or ungrounded. Equipment enclosures of commonly available sizes with various conductor configurations, or open air. Gaps between conductors. Faults involving three phases.
When Q2 turns on, it removes the base current from Q1, thereby reducing the collector current of Q1, which is nearly the load current. Thus, R sens fixes the maximum current to a value given by 0.65/R sens. For example, if R sens = 0.33 Ω, the current is limited to about 2 A even if R load becomes a short (and V o becomes zero).
The current breaking capacity corresponds to a certain voltage, so an electrical apparatus may have more than one breaking capacity current, according to the actual operating voltage. Breaking current may be stated in terms of the total current or just in terms of the alternating-current (symmetrical) component.
In an electric power system, a fault or fault current is any abnormal electric current. For example, a short circuit is a fault in which a live wire touches a neutral or ground wire. An open-circuit fault occurs if a circuit is interrupted by a failure of a current-carrying wire (phase or neutral) or a blown fuse or circuit breaker .
In an electrical grid, the short circuit ratio (or SCR) is the ratio of: the short circuit apparent power (SCMVA) in the case of a line-line-line-ground (3LG) fault at the location in the grid where some generator is connected, to: the power rating of the generator itself (GMW).