Abstract: A ground fault interrupter apparatus is provided that employs a switching device that is operated in two stages. The first stage operates a solenoid in order to close the contacts and preferably provides coupling between the load and the power source. The second stage maintains the coupling, however, drawing less current and power from the internal devices of the apparatus. Accordingly, the fault interrupter meets various standards for the time required to open and close the contacts as well as keeping the dissipated heat from the device within the required range.

Abstract: A GFCI is provided that has secondary test switch contacts. In case closing of the primary test switch contacts fails to trip the GFCI, subsequent closing of the secondary test switch contacts results in a short circuit between the AC input terminals of the GFCI. The short circuit blows a fuse disposed on the line side of the GFCI. The blowing of the fuse disables the GFCI and/or provides an indication to the user that the GFCI is defective.

Abstract: A stack of interleaved laminar products comprises a first and a second array of products, each of which has at least one branch interleaved with a corresponding branch of at least one product in the other array. The products are folded into a generally W-shaped profile comprising two outer branches and two inner branches, with the distal edges of the said outer branches projecting at least partially beyond the said inner branches, so that the said distal edges can be used for interleaving with at least one other product in the stack.

Abstract: A double density channel bank architecture compatible with an existing D4 backplane and D4 channel units transmits or receive PCM data on the PAM bus, while simultaneously transmitting or receiving PCM data on the PCM bus. A double density channel unit (CU) provides data for two transmit and two receive T-1 timeslots to increase the capacity of a D4 channel bank from 48 channels to 96 channels. Channel bank timing of PCM data on the PAM bus provides isolation of PCM data and PAM signals on PAM bus. Double density transmit and receive units each support an additional DS1. The receive unit transmits a signal on both CU channels to indicate T-1 failure and to commence trunk processing.

Abstract: A process for making packs of interleaved laminar articles, comprising the operations of: providing a first plurality of strips of laminar material, subjecting these strips to a first interleaving operation so as to create a composite strip having an interleaved structure in which the strips located at terminal positions have corresponding outer limbs which project with respect to the said composite strip, cutting the composite strip into lengths through a transverse cutting operation so as to give rise to successive separate lengths of the said composite strip, and subjecting a second plurality of the said pieces to a second interleaving operation performed by making use of the said projecting limbs so as to give rise to a further composite strip comprising interleaved strips in a number identified by the product of the said first and the said second pluralities.

Abstract: A faceplate assembly, for use with an electronic circuit card, comprising a faceplate and a movable plate, each including conductive portions or being made of a conductive material, and in electrical contact with each other. The faceplate is adapted to mount to an electronic circuit card, and has first and second opposite edges. The movable plate has a free edge and is movably coupled to the faceplate to move, by pivoting, sliding or the like, with respect to the faceplate between a retracted position and an extended position. Movement of the movable plate can be effected manually, or automatically by movement of the latches on the electronic circuit card assembly which latch the electronic circuit card assembly into an electronic circuit card housing.

Abstract: A multi-port power monitor is provided which indicates whether power is being supplied to one or more of a plurality of ports connected to external devices. The multi-port power monitor comprises a plurality of serially connected indicators and a plurality of controllable switches which supply power to the individual indicators when one or more of the corresponding ports are active.

Abstract: A two-wire channel unit or line card for use in a digital loop carrier (DLC) telephone system is disclosed. The channel unit is provided with a loopback test capability by using relays to open-circuit or short-circuit the input terminals of the hybrid circuit that couples the two-wire subscriber line to the separate two-wire transmit and receive paths within the channel unit. When open-circuited or short-circuited in this manner, the hybrid circuit couples voice frequency test signals between the receive and transmit paths of the channel unit, thereby allowing loopback testing to be carried out without providing a dedicated loss/gain circuit in the channel unit. An additional relay may be provided to vary the gain of an amplifier stage in the transmit or receive path of the channel unit during operation in the loopback test mode, in order to control the overall gain of the channel unit during loopback testing.

Abstract: An interface circuit is provided for implementing zero-byte substitution (ZBS) in a channel unit or line card which couples a digital subscriber line, such as a basic or primary rate Integrated Services Digital Network (ISDN) line, to a T1 network or other digital transmission facility. On the transmit side, the occurrence of an all-zero data byte in a B channel of the ISDN interface causes a corresponding zero byte indicator (ZBI) flag to be produced in the D+ channel, and also causes the all-zero byte to be replaced by the preceding non-zero data byte rather than by a prescribed or predetermined data byte. On the receive side, the occurrence of a repeated data byte in a B channel is detected and causes the current data byte to be replaced by an all-zero byte to restore the original data. The ZBI flag is then used as an error check bit to verify that the reinsertion of the all-zero byte was correct.

Abstract: A roof vent for preventing the buildup of hydrogen gas produced by battery charging in a remote digital telephone cabinet is provided with a movable splash guard for blocking the vent outlet when impinged upon by water and/or wind, thereby preventing the entry of water into the cabinet. The vent also includes a weatherproof cover whose lower edge is formed with scallops or undulations to maintain air gaps between the cover and the cabinet roof.

Abstract: A ground fault circuit interrupter (GFCI) line cord plug utilizes an electronically latched relay, rather than a circuit breaker or other type of mechanical latching device, to interrupt the AC load power when a ground fault condition occurs. In order to reduce the size of the relay and minimize the cost and complexity of the GFCI plug, the fixed and movable relay contact structures are mounted directly to the circuit board which carries the remaining components of the GFCI circuit. In a preferred embodiment, the fixed relay contact structures are integral with the plug blades of the GFCI plug. The movable relay contact structures preferably comprise deflectable spring arms which are preloaded when the relay contacts are in the open position in order to control the contact gap, and which are deflected past the point of contact closure when the relay contacts are in the closed position in order to increase the closing force.

Abstract: A control system for a network element (NE) such as a remote digital terminal (RDT) in an integrated digital loop carrier (DLC) system is provided which comprises subsystems for operating circuit packs and for providing functions that are common to the circuit packs. Each subsystem has a subagent residing on a network processor circuit pack. The subagents communicate via a common subagent interface. A NE which supports both OSI and non-OSI interfaces such as Transaction Language 1 (TL1) and Common Management Services Element (CMISE) interfaces is provided, along with a method for mapping TL1 commands to CMISE messages using TL1 proxy objects.

Abstract: A hot restart circuit for a high intensity discharge lamp includes a storage capacitor and SCR connected across a tapped portion of a ballast with a breakdown device to start the SCR. A charging circuit for the storage capacitor includes a diode, a pumping capacitor and an RF choke in series from the ballast tap to the AC line, and a further diode interconnecting the capacitors. The pumping capacitor increases the charge on the storage capacitor in a stepwise fashion until breakdown voltage is reached, whereupon starting pulses are applied to the lamp. A positive temperature coefficient (PTC) resistor stops the flow of charging current to the capacitors after a predetermined interval, thereby terminating the reignition pulses and protecting the starting circuit from damage in case the lamp fails to reignite. In an alternative embodiment, a MOSFET gated by an RC timing circuit removes charge from the storage capacitor in order to terminate the reignition pulses after a predetermined interval.

Abstract: A self-diagnostic circuit for an emergency lamphead is disclosed that is effective during standby operation of the lamphead to indicate whether the lamphead is capable of operating in an emergency mode. The self-diagnostic circuit includes a high-impedance circuit path connected in series with the lamphead and including an indicator, such as an LED, which is energized by a battery current passing through the circuit path and lamphead during the standby mode operation. The battery current is insufficient to illuminate the lamphead, but is sufficient to energize the LED whenever proper electrical continuity exists through the lamphead. A second high-impedance circuit path may be connected in parallel with the lamphead, in order to energize a second LED when proper continuity does not through the lamphead.

Abstract: A reverse wiring indicator for a GFCI receptacle alerts the installer in the event that the AC source has been improperly wired to the load or feedthrough terminals of the receptacle rather than to the source or input terminals. The reverse wiring indicator operates by open-circuiting one of the load or feedthrough terminals of the receptacle, and may take the form of a removable barrier which inhibits conduction through one of the power contact sets of the GFCI circuit breaker until the receptacle has been installed and successfully tested. The contact set through which conduction is inhibited is the one other than that to which the TEST switch is connected, and the other contact set is allowed to conduct in the normal manner.

Abstract: The light output of an electroluminescent panel is increased by using resonant transformation to increase the operating voltage across the panel to a level greater than the source or input voltage. This is accomplished by connecting the electroluminescent panel into a series resonant circuit whose capacitance value is made up at least in part of the intrinsic capacitance of the electroluminescent panel itself, and by choosing the inductance and capacitance values of the series resonant circuit to produce the desired output voltage across the electroluminescent panel. The resulting circuit is simple and low in cost, does not significantly add to the operating losses of the system, and takes advantage of the intrinsic capacitance of the panel in providing the desired resonant transformation.

Abstract: A simple and inexpensive air-to-air heat exchanger for cooling an electrical equipment cabinet or the like comprises a plurality of connected sections which are substantially identical to each other. In one embodiment, each section comprises a channel for carrying a flow of air and at least one heat exchange fin extending outwardly from the channel for exchanging heat between the air in the channel and the air outside the channel. In a second embodiment, each section of the heat exchanger comprises two adjacent channels which are open along one side, and the channels are closed off to form air flow conduits when the heat exchanger sections are attached to each other.

Abstract: An electrical circuit card adapted to be removably received in a grounded, electrically conductive housing comprises an insulative circuit board, an insulative faceplate coupled to the circuit board along the front edge thereof, and an electrically conductive shielding strip behind the faceplate for reducing EMI emission. The shielding strip comprises an intermediate portion extending generally vertically along the rear surface of the faceplate, resilient upper and lower spring arms extending rearwardly at an angle from the intermediate portion, and upper and lower contact pads at the ends of the respective upper and lower spring arms. The upper and lower contact pads form planar contact areas which are disposed at an angle relative to the spring arms, and which are parallel to corresponding electrical contact surfaces provided on the housing.

Abstract: An electrical equipment cabinet utilizes a door-mounted, air-to-air heat exchanger for providing cooling to the equipment housed in the cabinet while maintaining a closed or sealed environment within the cabinet. An arrangement of ducts and vents is used to force interior and exterior air through the heat exchanger using powered fans mounted within the main portion of the cabinet. The mounting of the heat exchanger on or within the door of the cabinet makes more efficient use of the space available within the cabinet, and the placement of the fans within the main portion of the cabinet protects them from damage and avoids the need to provide electrical power to the door.