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A crowbar circuit is an electrical circuit used for preventing an overvoltage or surge condition of a power supply unit from damaging the circuits attached to the power supply. It operates by putting a short circuit or low resistance path across the voltage output (V o ), like dropping a crowbar across the output terminals of the power supply.
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 ...
Overhead power lines are easiest to diagnose since the problem is usually obvious, e.g., a tree has fallen across the line, or a utility pole is broken and the conductors are lying on the ground. Locating faults in a cable system can be done either with the circuit de-energized, or in some cases, with the circuit under power.
Power system protection is a branch of electrical power engineering that deals with the protection of electrical power systems from faults [citation needed] through the disconnection of faulted parts from the rest of the electrical network. The objective of a protection scheme is to keep the power system stable by isolating only the components ...
A time-delay fuse (also known as an anti-surge or slow-blow fuse) is designed to allow a current which is above the rated value of the fuse to flow for a short period of time without the fuse blowing. These types of fuse are used on equipment such as motors, which can draw larger than normal currents for up to several seconds while coming up to ...
Calculation of the required breaking capacity involves determining the supply impedance and voltage. Supply impedance is calculated from the impedance of the elements making up the supply system. Customers of an electrical supply utility can request the maximum value of prospective short-circuit current available at their point of supply.
Due to the large switching voltages this transistor must handle (around 325 V for a 230 V AC non-power-factor-corrected mains supply, otherwise usually around 390 V), these transistors often short out, in turn immediately blowing the main internal power fuse. Power supplies in consumer products are frequently damaged by lightning strikes on ...
A switched-mode power supply operating at the current limit with the output short-circuited does not have increased power dissipation in the power transistor(s), so foldback current limiting is an application feature only rather than one that also prevents a load fault from also destroying the power supply. The safety benefit of reducing the ...