Abstract:
A direct current arc fault circuit interrupter includes separable contacts and a trip circuit to trip open the contacts. The trip circuit includes a number of alternating current sensors structured to sense a current flowing through the separable contacts, a number of filter circuits cooperating with the AC current sensors to output a number of AC signals, a number of peak detectors cooperating with the filter circuits to output a number of peak current signals, and a processor cooperating with at least the peak detectors. The processor inputs the number of peak current signals as a plurality of peak current signals or inputs the number of peak current signals and determines the plurality of peak current signals. The processor also determines if the peak current signals exceed corresponding predetermined thresholds for a predetermined time, and responsively causes the contacts to trip open.
Abstract:
A safety circuit for use in low-voltage systems improves safety of and additional features to low-voltage connections. When incorporated into a battery, the circuit leaves the battery disconnected from the low-voltage system until it determines that it is safe to make a connection. When the safety circuit determines that no unsafe conditions exist and that it is safe to connect the battery or low-voltage systems, the safety circuit may make the connection by way of a soft start that provides a connection over a period of time that reduces or prevents inductive voltage spikes. A method is used for detection of proper polarity of the connections between the battery and the low-voltage system. When incorporated into a jumper cable, the safety circuit provides communication abilities, can provide test abilities, and improves connection safety and functionality, such as allowing transfer of power between low-voltage systems having different voltages.
Abstract:
A protection system (1) for an IT electrical distribution system (EDS) (2) has a floating reference conductor (3) and two electrical conductors in the form of an active conductor (5) and a neutral conductor (6). System (1) includes two input terminals (7, 8) for electrically connecting to an MEN electrical power source (10) that is upstream of system (1). Two output terminals (11, 12) are electrically connected, via respective conductors (5, 6), to an electrical load in the form of an electrical motor (14) for a compressor (not shown) of an upright freezer display (15) having a metal cabinet (16). Motor (14) is downstream of the system (1). A protection device, in the form of an MCB (17), electrically connects terminals (7, 8) to respective terminals (11, 12) to allow a supply of electrical power from source (10) to motor (14). MCB (17) is responsive to a fault signal at a port (18) for selectively electrically disconnecting at least one of terminals (7, 8) from the respective output terminals (11, 12) to prevent the supply of electrical power. A sentinel unit (19) selectively generates the fault signal at port (18) in response to the current in conductor (3) being greater than a predetermined current threshold.
Abstract:
A surge protection element (50) for a conventional cable connector (10) includes a printed circuit board (50) preferably shaped as two concentric rings (58,54) connected by two spokes (56,57). The outer ring (54) is electrically connected to the grounded portion of the cable connector body. A printed circuit trace (62) on one of the spokes is separated from a printed circuit trace (66) on the inner ring (58) by a spark gap. If a high voltage surge is carried by the coaxial cable transmission line, a spark is formed in the gap. As a consequence, the high voltage surge is transferred to the surge protection element (50) which in turn conducts the electricity to the grounded body of the connector (10).
Abstract:
A power supply device capable of preventing a drive transistor from being damaged by heat when a collector output is grounded. A power supply device (10), which supplies for driving a drive current to the base of a transistor (20), has a lower-limit threshold value comparison unit (14) for comparing an actual collector output Vin with a lower-limit threshold value 0.5Vref of the transistor (20), and, when the collector output Vin is less than the lower-limit threshold value 0.5Vref, issuing a stop signal to a current control unit (18). Therefore, since the collector output of the transistor (20) grounding without intermediary of a load circuit (40) lowers the collector output Vin below the lower-limit threshold value 0.5Vref, the current control unit (18) receives a stop signal from the comparison unit (14) to stop the supply of a drive current to the transistor (20), thereby preventing damage to the transistor (20) by heat.
Abstract:
The present patent is a protection circuit against overcharge, that acts after having surpassed the nominal tension of a distribution net a.c. of 50/60 Hz, more the 10 % of tolerance, cutting it,not letting to pass it for the equipment for her fed, allowing, however, when the tension comes back at the normal level, the passage of the current again and automatically. In the circuit (1) when an overcharge of up to 1000 V enters in the equipment, it is dissipated through a filter and it does on a relay (RL1), that usually works shut, opening it to prevent the feeding of the equipments connected and protected. When the tension is stabilized returning to the normal levels the relay closes automatically and it returns to feed the equipments connected. The circuit is ideal for protection of televisions, computers, cordless telephones, cellular, central phone, scales electronics, medical-hospital equipments and laboratory, fax and all the electronic equipment of 127/220 V of up to 6 A, whose critical strip of damage is 280 V. Its application can also perform the public illumination protecting reactors, lamps and units of photoelectric relays, with great economy in the maintenance of these urban equipments.
Abstract:
A clock line over-protection circuit (28) carried on an interface card (16) for interfacing synchronous clock line (20), power line (22), DC common line (24) and data line (26) between a host computer (12) and a plurality of data link modules (14) with a plurality of associated controlled devices (18) including a series resistor (50) interconnected between a clock disable switch (52) and a clock signal generating amplifier (48) and a current sensor circuit (64, Fig. 3) connected across the series resistor (50) to produce a current sensor signal on an output (62). The current sensor signal is integrated by an over-current protection circuit (58, Fig. 4) to produce an over-current detection signal that varies with the difference in the clock line current magnitude during clock signal phases of opposite polarity. A clock switch control circuit (54) actuates the clock disable switch (52) to turn off and to protectively disconnect the clock line (20) and the data link modules (14) coupled therewith from the clock signal generating amplifier (48).
Abstract:
A terminal block (8) for terminating one or more exchange wires (62) to one or more service wires (18) has a housing (10) including a plurality of separate chambers each of which are accessible to a service wire through a wire access port. The terminal block includes an access jack (130) including a service wire junction contact (138) provided within a service wire junction contact slot (132), an exchange wire junction contact (142) provided within an exchange wire junction contact slot (136) and an earth junction contact (140) retained within an earth junction contact slot (134). Exchange wires are terminated to respective exchange wire junction contacts in the terminal block and the corresponding stub cable (60) is permanently secured thereto. One or more service wires are terminated and conductively connected to a service wire junction contact. A linking module (200) is provided which, when inserted into the access jack, forms a conductive connection between the service wire junction contact and the exchange wire junction contact. The linking module further includes a protection device (230) which provides protection to the service side and exchange side. The linking module may be removed and replaced as needed. Removing the linking module from the access jack severs the conductive connection between the service wire junction contact and the exchange wire junction contact.