Abstract: A protective relay, system, and relay operation method which allows logic functions to be distributed amongst multiple protective relays associated with a power distribution system. The protective relays include communications ports for exchanging messages over a peer-to-peer communications network, and include programmable logic. Each protective relay receives logic operands contained in the messages from remote protective relays, executes logic equations using the received operands, provides protective control if needed, and outputs operands to other protective relays.

Abstract: A semiconductor apparatus, including an intelligent power module, facilitates preventing sudden stop of an inverter due to an anomaly from affecting a factory operation adversely. When an anomaly occurs in IGBTs of the inverter, one of protection circuits outputs an alarm signal via an alarm enable line. In advance to the alarm signal, when the protection circuit detects a sign of a possible anomaly from a collector current or a chip temperature of any of the IGBTs exceeding a second predetermined collector current level or a second predetermined temperature level higher than the normal collector current value or the normal chip temperature but lower than a first predetermined collector current level or a first predetermined temperature level for outputting the alarm signal, the protection circuit outputs a preliminary alarm signal via a preliminary alarm line without turning off the pertinent IGBT.

Abstract: A telephone line monitoring and alarm apparatus capable of continuously monitoring telephone line status and activating an audio-visual alarm if the telephone line becomes inoperative, incorporates an integral telephone plug to permit direct plug-in connection of the apparatus to a standard telephone wall jack as a self-contained and autonomous unit without the use of interconnecting cables or cable-plug attachments. An integral dual telephone jack splitter permits the uninterrupted use of standard telecommunication equipment, such as telephones, answering machines, or facsimile equipment while the apparatus monitors telephone line integrity. Micropower circuitry derives electrical power from the telephone line to provide visual ON status indication, and from a battery source independently of the telephone communication line voltage, to provide continuous telephone line monitoring, audio-visual alarms and audio-visual low battery voltage indication.

Abstract: An insulated device diagnosing system is capable of judging the deterioration, lifetime, and defects of a device. The intensity at each voltage phase angle is measured at a plurality of specific frequencies, taking high voltage phase angles as the abscissas. The deterioration, lifetime, and the kind and extent of abnormality of the device are judged from the pattern and intensity of the spectral distribution, which is obtained by peak-holding the measured intensity for a defined time period. According to the present invention, partial discharge can be measured highly sensitively and precisely to diagnose the deterioration, lifetime and the extent of defect of the device. As a result, the insulation reliability of the device can be improved, and the part of the device that should be repaired/replaced can be grasped before disassembly of the device, thereby cutting the maintenance cost.

Abstract: This invention relates generally to patient monitoring systems and more particularly concerns devices and systems used to monitor bed patients in hospital or other care-giving environments. In accordance with a first aspect of the instant invention, there is provided a pressure sensitive mat which has been completely sealed around its exterior edges. The interior of the mat is kept in communication with the atmosphere by way of a section of flexible tubing which encloses the attached electrical line. One end of the tubing is sealed inside of the mat and the other end is open to the atmosphere, thereby providing a passageway for air to reach the interior of the mat. This arrangement, however, protects the interior of the mat from exposure to fluids near the perimeter of the mat and allows the mat-portion of the invention to be completely submersed without adverse effect, if that should become necessary.

Abstract: A circuit placed between an alternating current actuated device and a digital logic controller to isolate the digital logic controller from the AC line power and to provide a signal indicative of actuation of the alternating current device.

Abstract: A smart module circuit board carries a programmable microprocessor and a plurality of relay type interface circuits for use in organizing relatively high voltage input devices and output devices into a complex system wherein a programmed combination of input device signals determines when and if to energize one or more output devices in the system. The interface circuit comprises input and output stages which operate on logic level voltages and which are decoupled by opto-couplers from a relatively high voltage energization circuit which passes through a relatively high voltage electrical device. The energization circuit comprises a triac which is operated by the output stage in response to outputs from the microprocessor, a manual switch connected in parallel with the triac so that a given electrical load device can be manually activated and a multi-colored LED for indicating the conditions of the input and output circuits individually and in combination.

Abstract: A system (10) for detecting the state of a switch device (60) includes a driver circuit (40) having an output (42) operative to provide a driver output signal. An indicator (44) is electrically connected between the driver circuit (40) and the switch device (60). The indicator (44) is activated in response to the driver output signal and upon the switch device (60) being in a first state. A monitoring circuit (70), which is responsive to the switch device (60) through the indicator (44), is electrically connected to a node (64) between the indicator (44) and the driver circuit (40). The monitoring circuit (70) is operative to provide a first signal in response to the switch device (60) being in the first state and a second signal in response to the switch device (60) being in a second state. The monitoring circuit (70) controls energization of a controller (28) so as to power the controller (28) when the switch device (60) is in the first state.

Abstract: A switch status monitoring system (10) includes a switch signal processor (16) that operates in either of a supervised mode or an unsupervised mode for each monitored switch (12). Selection of the operating mode is made via configuration data provided to the switch signal processor, for example, from an applications processor (20). In this manner, reconfiguration of the mode of monitoring, supervised or unsupervised, of any particular switch within a system is accomplished by providing revised configuration data and without changes or modifications to the switch signal processor hardware. As will be appreciated, the present invention has application in for example door or window monitoring systems and in other similar security system applications.

Abstract: A method and apparatus for diagnosing whether a solenoid in an image forming system is functioning properly is disclosed. An actuating current is sent to a particular solenoid while a current waveform and elapsed time such as pull-in time value are noted for instances when the solenoid is in a first position and a second position. The first position can be one in which a solenoid plunger is extended and the second position can be one in which the solenoid plunger is retracted, or vice versa. Based at least partially on the measured actuating current values prior to the beginning and after the ending of solenoid movement, and measured time values, a determination can be made as to whether the solenoid is functioning properly by comparing these values to predetermined values for a properly functioning solenoid.

Abstract: The present invention is a snowplow diagnostic and connection system for connecting a snowplow to a vehicle. The system includes an diagnostic circuit and an indicator which detects and indicates the status of various components of the snowplow and its controls. The indicator includes a specific indication of the status of each detected subsystem or each component, as well as providing a general warning if any problem is detected. The indicator has a plurality of LED's which individually represent the various subsystems or components. If a problem is detected with any of the subsystems or components, the vehicle's headlights are caused to flash, thus alerting the operator.

Abstract: This invention relates generally to monitoring systems and more particularly concerns devices and systems used to monitor bed patients in hospital or other care-giving environments. In accordance with a first aspect of the instant invention, there is provided a binary switch-type device (e.g., a “mat”) for use in patient monitoring situations which contains, in addition to a conventional patient detection circuit, identification circuitry that can be sensed by an attached electronic monitor. The identification circuitry can be sensed by the electronic monitor and is designed to be configured to serve many different purposes, including, by way of example only, identification of the type of mat attached thereto, detection of connectivity problems, tracking mat usage time, and identifying mats that are nearing the end of their useful lives.

Abstract: A method for detecting faulty switching operations of a first relay whose switching element is connected in series with a load and which, depending on the switch position, interrupts or closes the connection to the load in accordance with switching commands. In this context, a current is detected flowing through a circuit containing the switching element, and a faulty function of the relay, in particular a sticking of the switching element, is detected if the current intensity does not correspond to the current intensity to be expected in accordance with the selected switching position. Further relays, which can be provided in order to commutate the potentials at the load, can be included in the test. The method makes possible a relay test without moving the actuators, assuming the relays are in order. In addition, this generates a time savings, since not all of the relays have to be triggered for the test.

Abstract: A flow detector includes solid state delay circuitry coupled to a flow indicating device. In response to flow being indicated, the delay circuitry is enabled. After a preset delay interval, if flow is still being indicated, an output signal can be generated. The flow indicating device can be a two-state mechanical switch. A mode setting element can be used to configure the detector for different types of installations.

Abstract: A switch status sensor is provided for counting on/off events of a switch of a water meter. When an on/off event is detected by a microcontroller, the microcontroller supplies a “signature” signal, which is distinguishable from electromagnetic noise, to the switch. If this “signature” signal is detected as having passed through the switch by the microcontroller, then it can be confirmed that the switch is closed. Alternatively, if the “signature” signal is not detected as having passed through the switch by the microcontroller, then it is verified that the switch is open. Thus, the switch status sensor can distinguish between false switch events caused by electromagnetic noise and true on/off events of the switch.

Abstract: A passive processing circuit for processing a ground side switch closure to a CMOS input (20) of an MCU, particularly useful in a D.C. electrical system where ground offsets may occur, such as in an automotive vehicle. Three resistors (R1, R2, R3) are connected between supply and ground potentials of a D.C. power supply voltage (10). The junction of two (R1, R2) connects to an output (16) of a grounded input switch (12). The junction of two (R2, R3) connects to the CMOS input (20). A fourth resistor (R4) connects between the bi-directional input/output (22) of the MCU and the junction of the second and third resistors. The MCU executes an algorithm that selectively allows and disallows the resistor (R4) to coact with the second and third resistors. The circuit provides a cost-efficient solution for extending the range of supply line voltage over which a CMOS input can correctly read a switch closure.

Abstract: Electrical consumers receive load current from a supply voltage via two or more power switches. A false-closure detection device includes a measuring device and a diagnostic device for the detection of faults. The measuring device is connected parallel to the power switches and the electrical consumer lying in series with the switches. A diagnostic voltage is compared as the output signal of the measuring device with a reference value for the detection of false closures in the load circuit.

Abstract: Apparatus for monitoring interruptions in utility power that includes a utility power plug for connection to a utility wall socket to provide a signal indicative of loss of utility power. A counter is responsive to such signal for counting and displaying the number of power interruptions, and a timer is responsive to such signal for measuring and displaying time duration of power interruptions. An operator switch is coupled to the timer for selectively measuring and displaying either duration of the latest power interruption or total duration of all power interruptions. The counter and timer may be reset at the option of an operator.

Abstract: A modular emergency stop device including a switch unit and a control unit. The switch unit includes a switch which converts from a normal state to an emergency state when an emergency stop is necessary and a housing for the switch. The control unit includes a controller which controls a power source for a machine and a housing for the controller. The switch unit's housing and the control unit's housing are adapted to be selectively coupled together and uncoupled from each other. The switch is operably coupled to the controller when the housings are coupled together whereby the controller may appropriately control the machine's power source when the switch is converted to the emergency state. To replace the switch, the switch's housing is uncoupled from the controller's housing to remove the switch unit and a new switch unit is coupled to the controller's housing.

Abstract: In the present method and apparatus for processing a vibro-acoustic signal emitted by a high-voltage switching system, the vibro-acoustic signal is converted into a digital signal. The digital signal is rectified and the resulting rectified signal is applied to a convolutional filter with a spectral window to produce a smoothed signal. The smoothed signal is decimated to produce a decimated signal representing an envelope of the vibro-acoustic signal. A time realignment of the decimated signal is carried out with respect to a reference signature to produce a realigned signal. Time deviation values generate an alarm if they exceed a limit threshold. The realigned signal is added as a factor of means providing a reference signature and an actualized signature. Variances of the realigned signal are calculated with respect to the reference and actualized signatures.

Abstract: The present invention relates to an inspection apparatus of an emergency exit light which is mounted on a wall or a ceiling in order to guide people to the emergency exit in a building in an emergency situation, such as a fire. Particularly, the present invention relates to the inspection apparatus of an emergency exit light for checking whether or not the reserve power supply charged in the secondary battery can be supplied to the emergency exit light to automatically turn on the exit light as soon as the domestic power supply which has been supplied to the emergency exit light is cut off due to the occurrence of an emergency situation, such as a fire.

Abstract: In a circuit for checking the correct contacting of a switch or pushbutton in a d.c. circuit, the switch or pushbutton is connected alternatively with at least one input and at least one output of a controller or microprocessor, and a capacitor arrangement is connected in parallel with the switch or pushbutton. Another embodiment, a coil arrangement is provided in the lead of the switch or pushbutton. In a method for checking the correct contacting of a switch or pushbutton which is connected at least initially with the output, the signal level output through the output corresponds to the signal level at the input in the case of correct contacting and actuation of the switch or pushbutton. The switches or pushbuttons are connected at least with the input after a change in the signal level, whereupon the signal level is evaluated.

Abstract: The present invention is a snowplow diagnostic and connection system for connecting a snowplow to a vehicle. The system includes an diagnostic circuit and an indicator which detects and indicates the status of various components of the snowplow and its controls. The indicator includes a specific indication of the status of each detected subsystem or each component, as well as providing a general warning if any problem is detected. The indicator has a plurality of LED's which individually represent the various subsystems or components. If a problem is detected with any of the subsystems or components, the vehicle's headlights are caused to flash, thus alerting the operator.

Abstract: A method of predicting an eminent circuit breaker trip condition using an intelligent electronic device such as a trip unit, a protective relay, a power meter or other IED is presented. The intelligent electronic device includes a microcontroller and associated memories. An algorithm (program) stored in a memory of the intelligent electronic device generates a near-trip event for each trip event calculation if preset thresholds for the measured parameters are breached.

Abstract: An electromechanical switching device includes at least one moveable contact and an associated drive in a device housing. Magnetic field sensors which are disposed at a suitable location inside and/or outside the device housing detect magnetic field values that are each linked to one of a plurality of switching states. The device housing has a switching handle which is intended for manual release. Through the use of a miniature inductance element with a ferrite core as a highly sensitive magnetic field sensor, a position of the switching handle or of a part coupled thereto is monitored and/or a current flowing in the switching device is detected.

Abstract: A hardwired, fail-safe rack protection monitor utilizes electromechanical relays to respond to the detection by condition sensors of abnormal or alarm conditions (such as smoke, temperature, wind or water) that might adversely affect or damage equipment being protected. When the monitor is reset, the monitor is in a detection mode with first and second alarm relay coils energized. If one of the condition sensors detects an abnormal condition, the first alarm relay coil will be de-energized, but the second alarm relay coil will remain energized. This results in both a visual and an audible alarm being activated. If a second alarm condition is detected by another one of the condition sensors while the first condition sensor is still detecting the first alarm condition, both the first alarm relay coil and the second alarm relay coil will be de-energized. With both the first and second alarm relay coils de-energized, both a visual and an audible alarm will be activated.

Abstract: A detection switch for enabling the setup sensitivity of the switch to be checked without lowering the movement speed of an object to be detected. A light reception section outputs a light reception signal RS corresponding to a light reception amount. A detection section amplifies the light reception signal RS and converts the amplified light reception signal RS from analog to digital form, then outputs the digital signal as light reception data RD indicating the light reception amount. A hold time control section 5 gives a hold timing signal HT defining a hold period to a hold circuit. The hold circuit holds the peak value or bottom value of the light reception data RD every hold period and outputs the hold value to a control section each time the end of the hold period is reached. The control section causes a display section to display the hold value.

Abstract: A flow detector includes solid state delay circuitry coupled to a flow indicating device. In response to flow being indicated, the delay circuitry is enabled. After a preset delay interval, if flow is still being indicated, electrical energy can be provided by a short circuit to an output device for the duration of indicated flow. The flow indicating device can be a two-state mechanical switch. A short circuit supplying switch can be implemented as a solid state or mechanical latching relay. The flow detector circuits can be used independently to provide local alarms. Alternately they can provide alarm indicating signals to a common alarm control panel.

Abstract: An add-on housing circuit usable with an existing garage having a switch controlled overhead incandescent screw type lamp socket and a conventional remotely controlled garage door opener with the same type of incandescent lamp socket. This housing has internal circuitry and an outer display panel and is operatively connected to an added fluorescent lighting fixtures within the garage in place of the conventional incandescent bulbs in the garage and opener. Either one or two electrically operated garage door openers may be used with the housing and fluorescent lighting fixtures. The housing's display face has visual indicators which indicate that the existing garage wall switch is operating to supply power to a fluorescent lighting system or that electrical power from the existing garage opener is received. If two garage doors and openers are used, then an additional visual panel indicator to indicate the operative state of the second door with supporting internal housing circuitry included.

Abstract: Insulating oil in electric power transmission switchgear such as a load tap changer for a transformer is filtered for removal of accumulated water and carbon particles. The filter and associated circulation pump is usually located in a separate cabinet external to the switchgear with circulation conduits connecting the filter, the pump and the switchgear reservoir. To prevent or minimize equipment damage that is presaged by excessive insulating oil temperature, oil flow within the oil circulation conduits is monitored for temperature excesses. Alarms are issued and electrical loads are disconnected upon detection of an excess temperature event. If desired, provision may be made for disconnected the jeopardized equipment from its respective service load.

Abstract: An electrical isolation device for use in an electrical distribution network having a plurality of branch circuits each defined by line and neutral conductors connected between a power source and a load, the line conductor being electrically connected to one of a plurality of line buses at an electrical distribution panelboard, the neutral conductor being electrically connected to a neutral bus at the electrical distribution panelboard. The isolation device includes a filter coupled between a selected number of line buses and the neutral bus at the panelboard and is designed to provide a low impedance path for an arcing fault occurring on either of the selected number of line buses. In another embodiment, the isolation device is comprised of a filter coupled between the line and neutral conductor of a selected one of the branch circuits and is designed to provide a low impedance path for an arcing fault occurring on the line conductor of the selected branch circuit.

Abstract: A motor operator is configured to provide local and remote operation of a power line phase switch. The motor operator has its components individually enclosed in a component enclosure and further enclosed in a main enclosure, allowing isolation and protection of the components from the environment and operators. A gear box includes a worm gear reducer submersed in oil providing a no maintenance gear train that makes continuous braking unnecessary by virtue of the inherently self-locking nature of the worm gear. The motor operator also includes a plurality of limit and auxiliary switches providing local and remote indication of switch position. The switches are each independently adjustable using cam adjustment collars. The overall configuration of the motor operator provides safe, reliable and cost effective phase switch operation.

Abstract: A wireless switch detection system (10, 100) includes central transmitter (22, 109) for transmitting a transmitter signal. The system (10, 110) also includes a remote switch (28, 128) spaced apart from the central transmitter (22, 109) and having at least two states. A tag circuit (32, 136) is responsive to and powered by the transmitter signal. The tag circuit (32, 136) detects the state of the remote switch (28, 128) and, in response to the transmitter signal, provides a tag signal indicative of the state of the switch (28, 128). A central receiver (26, 111) receives the tag signal.

Abstract: A power operator for switchgear and the like is provided that is capable of either power or manual operation without the necessity of any decoupling or mode selection. The power operator is compact and easily affixed over a manual operating shaft of switchgear. The manual drive capabilities are always coupled for operation without any backdriving of the power source. The power operator includes a drive output affixed to the switchgear operating shaft, a manual operating shaft, and an arrangement for selectively coupling a power-driven input to the switchgear operating shaft. In a specific arrangement, the control arrangement of the power operator senses the position of the drive output and also senses the current drawn by the drive source. When controlling switchgear having a stored energy mechanism, operating positions are detected by sensing the tripping of the stored energy mechanism via the sensed current through the drive source.

Abstract: Switching equipment with a contactor (CE) and a circuit breaker (BR) located ahead of the contactor. For detection of welded-together contacts of the contactor, this is provided with means (SC) adapted, a certain time after an opening order to the contactor, to apply a voltage pulse to the operating coil (12) of the contactor and to compare the current response of the operating coil with a comparison level for forming a detection signal (s.sub.d), which is supplied to the circuit breaker. Upon detection of welded-together contacts, the detection signal triggers an opening of the circuit breaker for disconnection of the contactor.

Abstract: An internal diode detection circuit for a device under test (DUT), a method of operating and a test fixture employing the same. In one embodiment, the internal diode detection circuit includes a source of electrical power that applies a reverse bias voltage to the DUT. The internal diode detection circuit also includes a current indicator, series-coupled to the DUT, that generates a signal when a current flows through the DUT. The signal indicates a presence of an internal diode in the DUT.

Abstract: A method for detecting the position of a switching device and an encapsulated switching installation having at least one switching device. A transmitted signal is emitted into the interior of an encapsulation to make it possible to easily detect the position of a switching device in an encapsulated switching installation. A resultant reflection signal is received and stored. After a repetition of this process, the two received reflection signals are compared with one another. In the event of any discrepancy, a message signal is produced for the new switching state.

Abstract: Disclosed is a system, for exchanging data among a plurality of devices, wherein a device can detect the state of another device without that device being powered on, and whereby usability can be enhanced.According to the system, during data communication a power supply device supplies power to a power reception device, and activates sections necessary for the power reception device. The state of the power reception device is detected by a power management unit, and the information that is obtained is transmitted across a data I/F unit to the power supply device, and stored in a storage unit. Based on the stored status information, the supply of power to the power reception device can be controlled.

Abstract: The system for determining protection quality of a protective relay and related functions of the protection system include obtaining information concerning the output status of the various protective elements in the relay. The status of various operations in the protective element are also evaluated against specific standards. The operation of supervisory and control elements affecting the action protective elements are also evaluated. Other aspects of the relay, including the availability of the relay and the operation of the voltage and current transformers are also evaluated. In addition, associated aspects such as the status of the communication channels, the station voltage availability and the condition of the trip and close circuits are monitored. All of the above is analyzed in a summary report to provide an indication of protection quality for the relay and associated protection system functions.

Abstract: Lamps LP1-LP9 are connected in a matrix form. Control devices Tr1-Tr6 are installed on connecting wires of the lines and rows of the matrix used for connecting the lamps LP1-LP9, respectively. Each of the connecting wires L1-L3 on each line is connected to a power supply Vcc via each of the control devices Tr1-Tr3. Further, each of the connecting wires L4-L6 is connected to the ground via each of the control devices Tr4-Tr6. Then the plurality of loads are connected to the control devices Tr1-Tr6 so as to control the loads by the control devices Tr1-Tr6, the number of which is smaller than the number of loads.

Abstract: The apparatus detects subsidence current from unfiltered as well as filtered secondary current values in the current transformer. A lack of zero crossings during a predetermined period is a reliable indication of the presence of subsidence current. If subsidence current is detected, then a signal is generated which indicates that the circuit breaker for the power system has opened, providing an accelerated indication thereof relative to an indication produced by an overcurrent element dropping out.

Abstract: An auxiliary switch provides an output or feedback signal indicative of the position or logical state of a contactor, disconnect or other principal device to which it is coupled. The switch is formed as a modular unit which can be fixed directly to the principal device, and is actuated by movement of elements within the principal device. An optical switch set within the auxiliary switch includes an emitter and detector pair aligned in mutually facing relation. An actuator is movable with the principal device and supports an optical shield. The actuator displaces the shield between a position clear of the optical path and a position interposed between the emitter and detector to change the state of the auxiliary switch. A power supply circuit may be housed within the switch for supplying power to the optical switch and to output circuitry. The device is particularly tolerant to contamination and can reliably output low level logic signals indicative of the state of the principal device.

Abstract: A power operator for switchgear and the like is provided that is capable of either power or manual operation without the necessity of any decoupling or mode selection. The power operator is compact and easily affixed over a manual operating shaft of switchgear. The manual drive capabilities are always coupled for operation without any backdriving of the power source. The power operator includes a drive output affixed to the switchgear operating shaft, a manual operating shaft, and an arrangement for selectively coupling a power-driven input to the switchgear operating shaft. In a specific arrangement, the control arrangement of the power operator senses the position of the drive output and also senses the current drawn by the drive source. When controlling switchgear having a stored energy mechanism, operating positions are detected by sensing the tripping of the stored energy mechanism via the sensed current through the drive source.

Abstract: A power supply unit adapted to supply power from a power supply section to a load via a plurality of power supply lines connected by an on/off switch and connectors. The power supply unit includes a load open detection section for detecting an open state between the on/off switch and the load, a monitor section for monitoring the number of times the open state has been entered per unit time based on the detection result of the load open detection section, and a control section for controlling the on/off switch off when the number of times the open state has been entered per unit time is greater than a predetermined number of times.

Abstract: The state of operability of a circuit having at least one group of condition responsive monitoring switches, the switches having first terminals connected to an input signal source and output terminals connected to an evaluation unit, is monitored by periodically interrupting the connection between at least one of the condition responsive switches of each group and the evaluation unit. The evaluation unit compares the change in potential at the output terminal of the one switch, resulting from the interruption, with the potential at the output terminal of another switch.

Abstract: A hand-held interface couples fill level detection switch terminals on a tank barge with current source terminals of a dockside facility. The interface includes a dockside connector adapted to be connected to the dockside terminals and a barge connector adapted to be connected to the barge terminals and test circuits for respectively testing the lading level detection switches. Each test circuit includes a battery connected in series with the light source of an optocoupler across a pair of terminals of the barge connector. Also connected across the battery are the light-sensitive switching element of the optocoupler, the coil of a normally-open relay and an indicator LED, the contacts of the relay being connected across a pair of terminals of the dockside connector. When the interface connectors are respectively connected to the barge and dockside terminals, the level detection switch under test completes the circuit across the battery through the optocoupler light source so that the optocoupler is energized.

Abstract: In an overhead power line switch, critical switch adjustment dimensions, switch position, switch status and other switch parameters are sensed by a plurality of particularly placed sensors, allowing determination as to whether the switch has operated correctly at critical points of the switch. The sensors also provide critical maintenance indication as to the operational status of the switch. In a preferred arrangement, the sensors are positioned to sense at least one of whether the contact blade is in a toggled closed position or a switch-open position, whether the contact blade is aligned with the clip assembly, the contact blade depth in the clip assembly, etc. The monitoring system is preferably provided with a remote terminal unit delivering sensor data to a remote operating facility.

Abstract: A taut wire fence system comprises wire-supporting anchor posts that maintain the taut wires of the system in tension. Sensor posts having tension sensors mounted therein are positioned between pairs of anchor posts to monitor changes in tension caused by intrusion attempts. To protect against attempts to bypass the tension sensors (such as by cutting the taut wires while using a frame device to maintain wire tension), one or more tensioned cable segments are provided in tension between the anchor posts (preferably along the lower portion of the fence) to form an electrical path. An electrical monitoring device is then used to monitor the continuity of the electrical path. The tensioned cable segments are preferably formed from a special cable that includes an outer layer which forms a physical barrier to cutting.

Abstract: Switching devices can have means for contactless switching position detection. According to the invention, magnetic field sensors arranged at suitable locations inside and/or outside a device housing are provided for switching position detection. In particular, position-dependent magnetic fields are measured for ON/OFF position detection, overcurrent triggering, and contact welding; however, the magnetic field of the current flowing is detected to recognize short-circuit triggering. Differential Hall effect sensors and Reed contacts, respectively, can be used for these purposes. In addition, a sound sensor can be provided for detecting the switching noise, whose signal is evaluated together with the overcurrent triggering signal for short-circuit detection.

Abstract: An appliance safety alarm including a first sensing circuit for detecting operation of the appliance, a second sensing circuit for detecting when an access cover, such as a dryer door or washer lid, is in the open condition, and a control circuit having first and second inputs in connection with the first and second sensing circuits and having an output controlling an audible alerting device. The control circuit is constructed in a manner to provide an activation signal to the audible alerting device when the access cover is opened while the appliance is in operation and when the access cover remains open for more than a predetermined period when the appliance is not in operation.