Search results
Results from the WOW.Com Content Network
An inrush current limiter is a device or devices combination used to limit inrush current. Passive resistive components such as resistors (with power dissipation drawback), or negative temperature coefficient (NTC) thermistors are simple options while the positive one (PTC) is used to limit max current afterward as the circuit has been operating (with cool-down time drawback on both).
In electrical engineering, current limiting reactors can reduce short-circuit currents, which result from plant expansions and power source additions, to levels that can be adequately handled by existing distribution equipment. [1] They can also be used in high voltage electric power transmission grids for a similar purpose.
A fault current limiter (FCL), also known as fault current controller (FCC), [1] is a device which limits the prospective fault current when a fault occurs (e.g. in a power transmission network) without complete disconnection. The term includes superconducting, solid-state and inductive devices. [2]
NTC thermistors can be used as inrush-current limiting devices in power supply circuits when added in series with the circuit being protected. They present a higher resistance initially, which prevents large currents from flowing at turn-on. As current continues to flow, NTC thermistors heat up, allowing higher current flow during normal operation.
Special current-limiting fuses are applied ahead of some molded-case breakers to protect the breakers in low-voltage power circuits with high short-circuit levels. Current-limiting fuses operate so quickly that they limit the total "let-through" energy that passes into the circuit, helping to protect downstream equipment from damage. These ...
Upon completion of pre-charging, the pre-charge resistance is switched out of the power supply circuit and returns to a low impedance power source for normal mode. The high voltage loads are then powered up sequentially. The simplest inrush-current limiting system, used in many consumer electronics devices, is a NTC resistor.
The surge is defined by the Combination Wave Generator's open-circuit voltage and short-circuit current waveforms, characterized by front time, duration, and peak values. With an open circuit output, the surge voltage is a double exponential pulse in the form of k ( e − α t − e − β t ) {\displaystyle k(e^{-\alpha t}-e^{-\beta t})} .
Current and voltage transformers to step down the high voltages and currents of the electrical power system to convenient levels for the relays to deal with; Protective relays to sense the fault and initiate a trip, or disconnection, order; Circuit breakers or RCDs to open/close the system based on relay and autorecloser commands