Abstract: A switch for use in an AC circuit wired in a three-way switch mode for supplying power to a load, has a first terminal for connection to an external line, second and third terminals for connection respectively to corresponding terminals of a second like switch, and a switch contact for selectively connecting the first terminal to either one of the second and third terminals. A transformer has its primary winding connected between the first terminal and the external line, and its secondary winding deriving an output voltage therefrom. The output voltage is rectified and supplied to a light-emitting diode. The ratio of turns of the windings of the transformer is such that the rectified voltage energizes the light-emitting diode when power is supplied to the load over its normal operating range. The light-emitting diode will thus provide an indication of when power is supplied to the load.

Abstract: A surge protection system having a plurality of surge protection devices for the protection of a power line. Each of the surge protection devices may be in either a ready state in which the surge protection device provides surge protection or an inoperable state in which the surge protection device does not provide surge protection. The surge protection devices provide a level of surge protection which is based upon how many of the surge protection devices are in the ready state and how many of the surge protection devices are in the inoperable state. The surge protection system includes means associated with the surge protection devices for generating a signal indicative of the level of surge protection, and means coupled to the generating means for displaying a visual indication of the level of surge protection. The surge protection system may also be provided with means for sensing a voltage on the power line and means for generating a visual display indicative of the voltage.

Abstract: A monitoring apparatus for a power plant including a plurality of direct current sources, includes a unit for displaying a predetermined number of symbols representing the direct current sources, and a unit for changing a displayed form of a corresponding symbol when at least one physical quantity of the states of the direct current sources changes.

Abstract: A modular peripheral error warning device for use with printers having a CENTRONICS parallel port. The peripheral error warning device monitors various voltages of connecting wires that interface with the computer and the printer and includes an interface box, an alarm box and a power supply. Activation of an alarm, such as a buzzer or LED, will occur if the monitored voltage corresponds to printer error, such as a paper jam. Correction of the printer error results in deactivation of the alarm.

Abstract: A barrier device threadably mounts to a cabling aperture on a field mounted transmitter. The field mounted transmitter receives and transmits signals, and is wholly powered by a current loop circuit. The barrier device has a conductive housing with at least a first and a second aperture and a pair of conductors passing through the first aperture of the barrier device, for connecting to a terminal block in the transmitter. A pair of signal terminals, preferably as ring tongue lug, is mounted in the second aperture of the barrier device. The signal terminals are connectable to a handheld communicator, which is used to calibrate, monitor and test the transmitter. A barrier circuit is mounted in the housing and is electrically connected between the signal terminals and the conductors. Signals from the communicator access the terminal block through the barrier circuit, and the barrier circuit limits the power available at the signal terminals.

Abstract: A voltage detection circuit includes a first resistive arm receiving an internal voltage to produce a basic current, current amplification circuitry to produce a reference current proportional to the basic current, a second resistive arm to produce a reference voltage representing the reference current, a voltage source to produce a control voltage from the reference voltage and a logic circuit to produce a binary signal from the control voltage, the state of the binary signal representing the value of the internal voltage.

Abstract: A sensor linked with a power cable to produce a first signal in response to the presence of at least one of a sensed current and a sensed voltage within the power cable. The measuring circuit is electrically connected to the sensor to produce a second signal in response to the first signal representative of the magnitude of at least one of the sensed current and the sensed voltage within the power cable. The measuring circuit also produces a third signal in response to the first signal representative of a sensed frequency of at least one of the sensed current and the sensed voltage within the power cable. The measuring circuit includes a model of a set of predetermined relationships between a plurality of reference frequencies and a reference amplitude for each of the reference frequencies for at least one of the sensed voltage and the sensed current of the power cable.

Abstract: A digital processing system including a first processor (11) and a second processor (21) connected in series between a first power supply node (101) and a second power supply node (103). The second processor is configured to operate at a variable processing rate, as controlled by the output of a processing rate controller (33) that is responsive to the voltage across the supply terminals of the second processor and a first reference voltage. An auxiliary shunt regulator (39) is connected across the supply terminals of the second processor and is controlled by a regulator controller (37) to prevent the voltage across the supply terminals of the second processor from exceeding a second reference voltage.

Abstract: The invention relates to a method for supervising the functioning of a plurality of valve units, a system for performing the method, a control unit and a control assembly for cooperation with the control unit. Each valve unit in the system comprises a semiconductor element (THY1-THYN) and a control unit for controlling the semiconductor element. The control unit comprises a trigger order input for receiving a trigger order (FP), an indication output for emitting a first indication signal (TP) and a trigger signal output (100) for emitting a trigger signal to the semiconductor element. The method comprises the steps: detecting a positive forward voltage (U.sub.T) across the semiconductor valve, generating a first indication signal (IP) when the forward voltage (U.sub.T) exceeds a first threshold value (U.sub.1), generating a trigger signal upon detected receival of the triggering order signal (FP), and the step: generating a second indication signal (SSTP) when the forward voltage (U.sub.

Abstract: A line monitor uses two wire data transmission in a fire alarm and detection system. A line voltage monitoring mechanism is within each wiring/contact monitoring circuit such that the exact value at any time of varying source voltage is known. The monitoring current resultant from the monitoring arrangement is strictly a function of impedance and not a function of source voltage because a line-monitoring scaling factor is incorporated into the final calculation. The monitoring scheme also results in the alarm and trouble voltage thresholds being suitably altered to take account of changed line voltage conditions.

Abstract: An apparatus for testing the operativeness of a squib in an active restraint system wherein the squib has a resistance value, when operative, within a predetermined range of resistance values. The squib is connected in series with a firing circuit to a first source of electrical energy. A monitoring circuit includes a second source of electrical energy and a bridge circuit. The bridge circuit includes a biasing resistor network and a reference resistor network, both networks being operatively connected to the second source of electrical energy. The biasing resistor network establishes a flow of test current through the squib, the test current being the only continuous non-actuating current through the squib. The biasing resistor network establishes a test voltage value at one terminal of the squib. The monitoring circuit further includes a comparator for comparing the test voltage value at the one terminal of the squib against the squib reference voltage value of the reference resistor network.

Abstract: A voltage regulator, a device driver, and a warning signal driver are provided on a single voltage regulator integrated circuit. The voltage regulator provides a regulated voltage for external logic such as a microcontroller. The device driver selectively turns on or turns off an external device such as a relay. The warning signal driver outputs a warning signal. The integrated circuit contains sensing circuits which sense if the output voltage is out of proper regulation. In the event of a malfunction, for example when the output voltage is outside a desired voltage range, the device driver shuts off the external device and the warning signal driver generates a warning signal. The integrated circuit may also receive signals from the external logic which cause the integrated circuit to shut off the device or to generate a warning signal.

Abstract: A method for monitoring an electrical drive, in particular a drive of an armature, having electric supply lines being extended through a switchgear plug-in unit associated with the drive and being connected at the plug-in unit to a measurement and evaluation unit, includes connecting at least one of the supply lines to the measurement and evaluation unit through a current transformer, and simultaneously operating and monitoring the drive with the plug-in unit. An apparatus for monitoring the electrical drive includes a switchgear plug-in unit associated with the drive. Electric supply lines of the drive extend through the plug-in unit. Voltage pickups and current pickups are disposed at the plug-in unit for a measurement and evaluation unit. Voltage measuring lines in the plug-in unit begin at the supply lines and end at the voltage pickups. Current transformers in the plug-in unit are associated with the supply lines without interrupting the supply lines.

Abstract: A location system for tracking miners underground includes a number of identification stations connected to a central control station. Miners are issued with portable identification modules which are fitted to their caplamps and which are powered by their battery packs. The identification modules transmit unique identification signals at intervals, which are picked up by the identification stations. The identification modules change the intervals between successive transmissions continually, and the identification stations can read overlapping transmissions, so that the reliability of detection is good. Miners who are issued with a caplamp first pass an identification card through a reader, which reads a unique personal identification code from the card. This code is correlated with the identification code of the identification module in the caplamp at the central control station.

Abstract: A vehicle warning system for warning a vehicle operator of a dangerous condition resulting from an abnormal engine parameter for use in a vehicle having a sensor for measuring the engine parameter and a gauge connected to the sensor by a line. The vehicle warning system includes an input port, a connector for connecting the input port to the line connecting the sensor and the gauge, a voltage detector for detecting when a voltage level at the input port exceeds a threshold level, and an alarm generator for warning an operator of a dangerous condition when the voltage detector detects that the voltage level exceeds the threshold level.

Abstract: An electrical test device for use by an electrician in testing circuits. The device includes a voltage sensor, display, and steady current source. The voltage sensor monitors the type of voltage (AC or DC) between the two conductors, and provides a signal to the display which responsively displays the type of voltage and the voltage level. The power supply has a steady current source that is in series with a tactile transducer, so that the test device may measure a broad range of voltages while only a limited amount of current flows through the voltage sensor. Consequently, lower cost components may be used in the voltage sensor. In another embodiment, the tester also includes a substantially independent continuity tester. The continuity tester includes its own power supply and alarm to indicate the continuity of a conductor and, thus, may operate even if the voltage sensor and display become inoperable.

Abstract: An electrical test device for use by an electrician in testing circuits. The device includes a voltage sensor, display, and steady current source. The voltage sensor monitors the type of voltage (AC or DC) between the two conductors, and provides a signal to the display which responsively displays the type of voltage and the voltage level. The power supply has a steady current source that is in series with a tactile transducer, so that the test device may measure a broad range of voltages while only a limited amount of current flows through the voltage sensor. Consequently, lower cost components may be used in the voltage sensor. In another embodiment, the tester also includes a substantially independent continuity tester. The continuity tester includes its own power supply and alarm to indicate the continuity of a conductor and, thus, may operate even if the voltage sensor and display become inoperable.

Abstract: An electric fence energizing apparatus is described in which a chargeable capacitor is connected to the primary winding of a transformer. The secondary winding of the fence is connected to receive pulses at the discharge of the capacitor, the discharge time serving as a measure of the voltage of the corresponding output pulse on the fence. The primary winding of the transformer is divided into two oppositely connected windings. The capacitor is arranged to be discharged through a first one of the primary windings. A voltage determined by the discharge of the capacitor is produced over the second of the primary windings during the discharge process. A measuring unit measure the time of the duration of this voltage over the second winding determined by the discharge of the capacitor.

Abstract: A low voltage indicator circuit including a self-biased driver circuit. A voltage at the output terminal is used to create a bias voltage to operate the driver when less than a threshold voltage is present on at least one voltage supply line. A transistor for supplying base drive current to the driver has a base coupled to the at least one voltage supply line in one embodiment and to the bias circuit in other embodiments. The transistor in the one embodiment provides base drive current to the driver when voltage on the at least one voltage supply line is less than the voltage on the output terminal by at least a predetermined amount. In other embodiments, the bias circuit may include a FET or resistor coupled between the output terminal and the base of a bias circuit transistor. The bias circuit transistor has a terminal connected to a bias resistor for providing current through the bias resistor when the bias circuit transistor is turned on.

Abstract: A method and apparatus for detecting power lines including a pickup coil for detecting the magnetic field generated by the current conducted by a power line and for producing a sense current in response to the detected magnetic field, a gyrator circuit for generating a sense voltage in response to the sense current and tuning means for producing an output voltage in response to the sense voltage such that a power line can be detected thereby. The tuning means also tunes the power line detecting apparatus to the predetermined frequency of the current conducted by the power lines. The power line detecting method and apparatus also preferably analyzes the magnitude and frequency of the output voltage produced by the tuning means so as to distinguish output voltages generated in response to the magnetic fields produced by power lines from those generated by extraneous electromagnetic noise.

Abstract: An output circuit in which both the signal type (i.e., current or voltage) as well as the signal level range (for example, 0 to 10 V, -10 V to +10 V) are based on user input parameters. The circuit is integrated in an application-specific integrated circuit (i.e., ASIC).

Abstract: A third rail warning device in which the third rail carries in use a dangerously high voltage. Connected to the third rail is a source of relatively safe voltage as a warning that the dangerously high voltage is about to be applied to the third rail. A time delay is employed to terminate the safe voltage and permit automatic connection of the dangerously high voltage, and an alarm is actuated when the safe voltage is being applied to the third rail.

Abstract: A measurement circuit in the output circuit of a sensor detects the polarity of a source to which a load is connected. The detection of one of the two polarities establishes one of two states which is stored in a storing element and the correct one of two drivers is switched to the output terminals. This state is maintained for as long as there is no change to the polarity at the output terminals. If the terminals are interchanged, then the measurement circuit correctly restores the stored state, so that the correct driver is associated with the load in each case. If positive instead of negative switching sensors are required, there is no need to replace the equipment. When the voltage is turned on, the equipment is initialized, so that it is set in accordance with the new circumstances.

Abstract: A faulted circuit detector having an electrically isolated and remotely positioned indicator detects fault currents in a monitored conductor. When a fault of a predetermined magnitude is detected, a light pulse is transmitted from the detector to the indicator via a fiber optic cable where, upon receipt, the pulse is converted to an electrical pulse causing the indicator to indicate a "fault" state. A reset circuit within the indicator resets the indicator at regular intervals to the "normal" state as long as a predetermined minimum voltage is present on the monitored conductor. The detector includes a temperature compensation circuit and low pass filter circuit so as to prevent misoperation due to varying ambient temperatures or high frequency transients. A test circuit is also provided to allow service personnel to field-test the device with the monitored conductor in an energized state.

Abstract: A detector for detecting electrostatic discharge events in an electronic component, assembly or system and including a display element which produces an immediate indication on exposure to a change in voltage level, an electrostatic discharge sensor, and circuit means for connecting said sensor to said display element. In one embodiment, the detector and the board or other device to be monitored are mounted in a housing having a visual access window with the display element of the detector viewable through the access window and with the detector positioned at the electronic device being monitored.

Abstract: The present invention relates to an LED traffic signal light containing numerous LEDs and a voltage compensation circuit which allows the traffic light to operate over a wide range of input power voltages, while generating sufficient light intensity to control traffic at a highway intersection. The voltage compensation circuit achieves these objectives without substantially increasing the power consumption, overall cost, or failure rate of the LED traffic signal light. In the preferred embodiment, the voltage compensation circuit disables or rearranges a first and then a second set of LEDs in the traffic light, as the input power voltage drops below a first and then a second threshold voltage, so that the remaining LEDs will be driven by an increased current and generate a greater overall light intensity than if all of the LEDs were driven by the decreased current that would result from the decreased input power voltage.

Abstract: A workstation mat used to monitor radio frequency, electromagnetic field induced currents flowing through the body of a person standing on the workstation mat. The workstation mat includes an upper and lower conductive plate residing in parallel planes. The upper plate is superposed in spaced apart relation over the lower plate. The mat also includes an electronic circuit coupled to the conductive plates. The electronic circuit senses the induced current flowing through a person's body and sounds an alarm to warn the worker when the induced body current meets or exceeds a predetermined current threshold. The threshold setting is variable and preset by the user. The workstation mat has a reset button switch mounted on one lateral side and contains connectors for a remote alarm and a remote reset switch.

Abstract: A location system for tracking miners underground includes a number of identification stations connected to a central control station. Miners are issued with portable identification modules which are fitted to their caplamps and which are powered by their battery packs. The identification modules transmit unique identification signals at intervals, which are picked up by the identification stations. The identification modules change the intervals between successive transmissions continually, and the identification stations can read overlapping transmissions, so that the reliability of detection is good. Miners who are issued with a caplamp first pass an identification card through a reader, which reads a unique personal identification code from the card. This code is correlated with the identification code of the identification module in the caplamp at the central control station.

Abstract: The contact between a device under test (DUT) and a measuring terminal is accurately judged with a simple circuit for impedance measurement. The conduction detecting means injects a judging current into the voltage terminal (L.sub.P) for low voltage. When the device under test (DUT) and both the current terminal (L.sub.C) for low voltage and the voltage terminal (L.sub.P) for low voltage are normally contacted with each other, since the inverting input terminal of the inverting amplifier is virtually grounded, and the L.sub.C and L.sub.P are substantially kept at the ground potential, the contact judgment for L.sub.C and L.sub.P is made by detecting the potentials of L.sub.P. In addition, when the impedance measurement value is larger than the predetermined lowest limit value and the current measurement value is lower than the predetermined lowest limit value, the DUT and the current terminal (H.sub.C) for high voltage are considered to have improper contact with each other.

Abstract: An improved input module is able to sense the ON and OFF states associated with an external signal, wherein that signal complies with standards denoting the ON and OFF condition thereof. The improved input module includes a fixed impedance and a parameter sensor, such as a voltage sensor, which senses at least a portion of the voltage drop across the impedance. In addition, the module includes a current limiter in series with the impedance so as to limit the current flow through the impedance when the threshold parameter has been exceeded. An additional embodiment of the input module includes a second current limiter which is able to selectively detect broken wires associated with the connection of the external signal to the input module.

Abstract: An electronic sensing circuit, which can be used in place of a linear variable differential transformer (LVDT) has four piezoresistor elements in a Wheatstone bridge configuration. A source voltage is applied across a first pair of bridge points, and the resulting junction voltages appearing at a second pair of bridge points are applied to a pair of inverting amplifiers in balanced configuration which provide first and second output voltages which change relative to each other depending upon the direction and amount of pressure applied to the piezoresistor elements in a manner similar to the output voltages provided by an LVDT.

Abstract: A plurality of sensors, such as a door handle lift switch, a headlight switch, and an ignition switch, are normally provided in an automotive electrical system. A master microcontroller normally is coupled to each of these sensors for receiving a signal therefrom and responsive thereto generating a corresponding controller signal. Power drivers, each operatively coupled to the master controller, normally are provided for energizing and powering loads coupled thereto, with each load being either an indicator or actuator that is operated responsive to its corresponding sensor. The self-diagnostic method includes the steps of mechanically actuating a selected one of the sensors, and then electrically actuating a first confirming indicator, such as an audible chime, indicative of the master controller receiving and successfully processing the corresponding sensing signal.

Abstract: A voltage monitoring device for an AC power distribution system utilizes a liquid crystal optical shutter device capacitively coupled between a conductor of the system and electrical ground such that the transparency of the optical shutter device to light varies with the system voltage level. A light source projects a light beam through the optical shutter device to a light detector such that the output of the light detector is dependent on the system voltage. A control circuit responsive to the output of the light detector provides an output signal when the system voltage falls outside of a predetermined operating range.

Abstract: A monitor and indicating circuit for an electric appliance detects the absence of the energization voltage for the appliance exceeding a predetermined threshold and provides a brilliant flash from a xenon lamp which is visible from great distances. The circuitry is contained within a sealed housing and includes a self-contained battery supply and attachable to a fence post. The circuit employed is specifically designed to conserve battery power by controlling the flash frequency and the charging time for the storage capacitor used with the xenon flash tube.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems. The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded. A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square rot of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square root of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An instrument for measuring voltage harmonics and current harmonics on AC (alternating current) power systems. The instrument includes the ability to determine when threshold limits have been exceeded for harmonics. The instrument also includes timing thresholds whose inputs are activated when the harmonic thresholds are exceeded. A single harmonic threshold is applied to measurements from multiple phases on poly-phase systems by comparing the square root of the sum of the squares of measurements from each phase to the harmonic threshold. Three indicators show when voltage harmonic limits are exceeded, current harmonics limits are exceeded, or both voltage and current harmonic limits are exceeded simultaneously.

Abstract: An apparatus for combination with a standard range having burners thereon and a power line connected thereto is provided and senses the current through the power line for a pre-set level, times the current once the pre-set level is reached, interrupts the current, signals when interruption of the current has occurred and includes controls for controlling the timing and the signalling in the apparatus.

Abstract: A voltage detector to sense deviations of instantaneous value of a monitored voltage from a desired value is provided. The system includes a reference voltage source for providing a reference voltage. A divider responsive to the monitored voltage and the reference voltage divides the reference voltage by the monitored voltage. Thereafter a window comparator responsive to an output of the divider produces an indication when the output of the divider is either higher than some predetermined high value or lower than some predetermined low value.

Abstract: In cooperation with an electric fence, a grounding rod directed into a ground supporting surface includes electrical communication with a fluorescent tubular light, with the tubular light having an upper distal end and electrical contact structure, to include a clip member for securement to an electrical fence in cooperation therewith to indicate electrical operability of the fence and its activation.

Abstract: A control for a clothes dryer with an induction drive motor and an electric resistance heater element. A single sense winding is threaded through sensors monitoring drive motor current and heater current, generating an output voltage each time the alternating motor or heater current passes through a zero-crossing. The control monitors the ON/OFF condition of the heater and samples the lagging phase angle of the motor current, and provides an improved system of detecting when the clothes load is dry. The control provides a clothes cool-down period with controlled moisture regain as per the user dryness selection. Numerous heater related diagnostic conditions are monitored at the start of each cycle, or, throughout each cycle, including: heater ground fault detection; 208 or 240 VAC service voltage identification; heater open/short circuit detection; open door detection; heater box thermostat cycling; and restricted air flow detection.

Abstract: A differential protective relay system includes protective relays 19A and 19B at the terminals of a protected transmission line segment 21. Analog signals QL1 and QL2 are sampled at the respective ends of the protected line segment 21, digitally encoded using delta modulation and biphase-mark encoding, multiplexed and transmitted over a 1.544 Mbps T1 communication channel 20 to the other end of the line where they are decoded and compared with the local signal at that end. Power is removed from the protected line segment if the difference between the local and remote signals exceeds a predefined value. Biphase-mark encoding is employed so that a clock signal may be recovered from the decoded signals.

Abstract: A method for monitoring damage to the protective covering of immersed or underground metal structures subjected to cathodic protection, based on the electrical resistance offered by said covering, and consisting of modulating the cathodic protection feed current and measuring the corresponding potential variation due to the ohmic loss, said resistance being obtained from the ratio of potential variation to modulation current, to activate an alarm system on sudden fall and rise in ohmic resistance due to accidental events.

Abstract: An electric power circuit with line voltage failure detection includes a pair of DC conductors for receiving a DC voltage, a capacitor connected across these conductors, and a main power converter connected to produce an output voltage on a main power bus in response to the DC voltage on the power conductors. A circuit branch connected across the power conductors includes the series connection of a primary winding of a transformer and a switching device. The switching device is operated to produce a series of voltage pulses across the secondary winding of the transformer. These voltage pulses are used to produce a second output voltage. The magnitude of these voltage pulses which occur during time when the switching device is off, is detected and a line failure indicating signal is produced when this magnitude falls below a predetermined value.

Abstract: A process for metering electric power passing via a certain point in a single-phase system comprises current (12) and voltage (U) stages at that point in the system and a processing stage for this information to generate data on the measurement of electric power. Each current data acquisition stage comprises the following steps: A) injection, into a winding (10a) of a magnetic circuit (10) with a predetermined structure surrounding one (LA) of the lines (LA, LB) of the system, of a current (Il+Ic) substantially proportional to the sum of a modulation current (kIl) and a "compensation" current (kIc); and B) detection at the terminals of the winding (10a) of an overvoltage leading to the immediate acquisition of the compensation current (kIc) as an image of the current passing through the line (LA). Use in the electronic metering of power in domestic installations, especially with facilities for remote transmission and information.

Abstract: An apparatus and method for monitoring voltage on a LAN cable on which data is conveyed by negative-going pulses. Positive voltage on the LAN cable is interpreted as noise. Positive voltage is detected by, for example, comparing the voltage on the LAN cable to a positive reference voltage, determining the peak positive voltage on the LAN cable, or determining the average positive voltage on the LAN cable. Upon the detection of positive voltage on the LAN cable, the presence (and possibly the amount) of noise is indicated to a person or data processing system which supervises the LAN called a LAN sentinel. The apparatus or method could be implemented in a Media Attachment Unit (MAU) with audio, visual or electronic noise indication means. Alternatively, it could be implemented as a hand-held diagnostic tool.

Abstract: During the piloting of the load, the current intensity and the voltage present in the load are monitored by the comparison of their values with a current threshold and with a window of permissible voltage values. When the voltage is outside the window of permissible values and/or the current falls below its threshold, a fault message is generated and the nature of the fault (open load, short circuit to earth, short circuit to the supply voltage) is also identified by the emission of a corresponding signal of a diagnostic nature. The identification of the faulty stage or stages is also provided for in the case of a circuit including several stages in parallel.

Abstract: An enclosure is provided for circuit modules which are mounted as an array in a vertical orientation within a card cage and which are electrically coupled to a back plane positioned rearwardly within the housing. A plurality of specified voltages asserted from a primary power source within the housing are monitored by a microcomputer based control system performing in conjunction with programmable memory. The status of the voltage sources is displayed at a supervisory panel mounted at the front face of the enclosure. This supervisory panel includes an array of light emitting diode based indicators which display both acceptable performance and out of tolerance performance to the operator. The outputs for each channel additionally are associated with a reset switch permitting a form of operator interrogation of any channel in question. The heat transfer air path of the enclosure is initiated along the sides of the enclosure where conveniently accessible elongate and vertically oriented filters are positioned.

Abstract: The invented circuit includes an I/O driver capable of supplying current to an I/O connector, a current detection circuit that may include a current limit resistor and a differential amplifier, a comparator to compare the level of current to a predetermined level and to produce an output signal based thereon, and a translator to convert the output signal from the comparator into a transistor-transistor logic signal. The device that includes the invented circuit then interprets the logic signal as identifying either a serial I/O system or a LAN I/O system.

Abstract: A circuit arrangement for monitoring two operating voltages of different polarity detects and indicates the deviation of either operating voltage from its nominal value beyond a predetermined tolerance limit. A transistor is provided, whose base is connected to the positive operating voltage across a first zener diode and to the negative operating voltage through a first resistor, and whose emitter is connected to the negative operating voltage through a series connection of a second zener diode and a second resistor, and to a reference potential across a diode.