gPatent LLC
Electrical protective device for low-voltage direct current (LVDC) network
An Electrical Protective Device for Low-Voltage DC networks (EPDL) has a controller that on start-up first closes a mechanical relay in a ground line, waits a first delay, then closes a bipolar transistor to allow current to flow through a positive supply line, then turns on a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET) connected in parallel with the bipolar transistor once an output voltage reaches a minimum target. The controller reverses the start-up order to open the MOSFET, bipolar transistor, and finally the relay when an over-voltage, input-power, or integrated-current fault is detected. The output current is integrated over time and compared to a threshold, allowing for capacitor charging or other temporary over-loads. When the output voltage dips below the minimum target, the MOSFET is turned off until the voltage recovers. If the voltage does not recover within a time period, the bipolar transistor and then the relay are turned off.
Hong Kong Applied Science and Technology Research Institute Company Limited
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Xin Kin Lap Tin Ho
Li Wong Li