Abstract: Automatic switching apparatus for a hand held electrically operated appliance such as a pressing iron. A motion sensor and an electronic timer cooperate to automatically shut off the iron if the iron remains stationary for a predetermined period of time. A simplified mechanism is manually operable in the event the user desires to reactivate the iron. A circuit board mounting simplified electronic circuitry is located within the handle of the iron. An appropriate indicator informs the user whether the iron is in the active mode or in the inactive mode.

Abstract: A triac and a mechanical relay, in series with the electrical heater of an incubator, together switch heater current on and off at the same set point temperature if the triac fails short. Similarly, a second mechanical relay in parallel with the triac switches heater current around the triac, should the triac fail open.

Abstract: Apparatus and method for monitoring a self-regulating heater comprising a PTC conductive polymer while it is being powered by a power supply signal. The apparatus is connected to a power supply and to the heater, the heater then producing a heater signal which is fed to a comparator. The comparator deterines the phasal relationship between the power supply signal and the heater signal and indicates when the signals are out of phase by a predetermined magnitude.

Abstract: An apparatus to monitor a circuit in which an AC voltage source is connected to a plurality of paralleled current consuming loads, such as heaters, including a reactive load in parallel with the current consuming loads at a point in the circuit more distant from the voltage source than any of the current consuming loads being monitored, a phase shift detector connected to the current consuming loads and at a point in the circuit between the voltage source and the nearest current consuming load being monitored, the phase shift detector being sensitive to the shift in current phase induced by the reactor load, and an alarm connected to and actuated by the phase shift detector which provides a warning when the phase shift induced by the reactive load is lost, indicative of a failure in the circuit.

Abstract: A monitor is disclosed for monitoring the operation of an electrically powered load, such as a solenoid or a resistance heater. The load is connected across a power source and normally draws current therefrom. An integrated circuit includes means for energizing a load on indicator so long as the load is drawing current. A power on indicator is energized so long as the monitor receives power from the power source. When the monitor senses that current is no longer being drawn by the load it energizes a flashing on-off fault indicator.

Abstract: An alarm system for an electric range which detects when a burner is energized without a utensil in place on the burner wherein the sensing means comprises an electrical switch mounted below the stovetop having a first switch position and a second switch position, a pin slidably passing through an opening in the stovetop beneath the rim of the dish under the heating element in contact with the underside of the rim and biased against the rim with a pressure sufficient to lift the rim from the stovetop when no utensil is present on the heating element, but insufficient to lift the rim when a utensil is in place on the heating element; and means connecting said pin with the switch to operate the switch between first and second positions corresponding to the position of the pin when a utensil is present or absent from the heating element.

Abstract: Current provided to a generally constant impedance load is monitored to detect a predetermined load current decrease not resulting from normal load voltage fluctuations, such decrease indicating an abnormal increase in load impedance. A latching alarm is actuated when the predetermined load current decrease is detected. The degree of load current decrease tolerable without activating the alarm is determined by a user-adjustable percentage-of-change sensitivity control. A logic gate blocks alarm functions when the load current decreases to an abnormally low level. The disclosed device can be used to monitor the status of a line voltage energized heat trace cable constituted by a plurality of parallel-connected resistance wire heating elements. Multiple monitoring devices can be used in conjunction with a master alarm which can be reset without resetting the particular monitoring device alarm that triggered the master alarm.

Abstract: The present invention is directed to a device for detecting faults in an electrically-conductive heating element and more specifically concerns a digital monitor which compares internal electrical noise produced by the electrically-conductive heating element with external electrical noise produced by the heating element power source in order to determine whether faults exist in the heating element.

Abstract: A sensing and indicator system for monitoring multiple electric heating elements connected in three-phase balanced Y circuits in heat reactivatable adsorbent gas fractionators. The system senses a failure induced imbalance, pinpoints the location of the group with the failure and causes a failure indicating alarm to function. The system operates by a sensing circuit including a discharge bulb sensing the failure induced imbalance and causing a conduction of current through the system resulting in the activation of an alarm and the illumination of the gas discharge bulb indicating which of multiple sets of heating elements has failed.

Abstract: A self-monitoring heat tracing system including a heating conductor, a monitor conductor, and a control circuit which monitors the integrity of the heat tracing conductor and provides alarm signals to indicate abnormal temperature conditions in the heating system or discontinuities in the monitor circuit.

Abstract: A system for monitoring heater elements of electric furnaces so as to identify individual failures, such system comprising an arrangement for detecting the electrical open state of any one of the heater elements, including a current transformer for monitoring current flow; and the capability of monitoring element voltage, such that no element current in the presence of a minimum element voltage is defined as, or taken to be, a failure; further including the provision of a master alarm indication of a defined failure in any of the elements and also an individual alarm indication to indicate which element has failed.

Abstract: A temperature detecting heating control system provides a temperature sensor, first and second voltage comparators for detecting a set point temperature and a warning temperature, and alarm circuitry for producing intermittent and predetermined period alarm signals in response to the detecting of the warning temperature and set point temperature respectively.

Abstract: Apparatus for detecting loss of AC power supply for an electrical conductor and loss of current through the electrical conductor when the power supply is connected thereto comprises voltage responsive means operable to produce a voltage present signal when the power supply is connected to the electrical conductor and a predetermined voltage is present across the conductor and a voltage absent signal when the predetermined voltage is not present across the conductor, and current responsive means operable to produce a current present signal when a predetermined current is flowing through the conductor and a current absent signal when the predetermined current is not flowing through the conductor.

Abstract: A system is disclosed for indicating when a flow heater used for vaporization of water and heated by PTC resistors as heating elements therein must be decalcified. Within the flow heater a PTC resistor element is located at a water entry and also at a water exit region. A main PTC heater element is also provided between the entry and exit elements. Separate power supply lines are run to the exit and entry heating elements and an electronic circuit is provided which determines when a difference in current flow in the exit heating element compared to the entry heating element exceeds a given value indicative of the need for decalcification. The circuit connects with an indicator which is triggered when decalcification is required.

Abstract: A DC current level detector is provided for monitoring the heater current of a pitot tube. The detector includes a toroidal core defining a bore through which can be passed a line carrying the current to be detected whereby an amount of flux is generated in the core according to the current to be detected. A reference circuit is provided to generate in the core a reference amount of flux against which the first flux is compared in an algebraic combination. An oscillator circuit is inductively coupled to the core to saturate the core in opposite directions. The algebraic difference between the fluxes is employed to generate a signal to operate a relay. The relay is included in a circuit in which are connected a power source and an indicator such as an alarm lamp. The core is of toroidal shape and a casing is provided which houses the core along with the associated circuits and which is provided with an opening corresponding with the bore of the core.

Abstract: Safety back-up and alarm circuit for loads such as electrical heaters and the like comprising a back-up substitute load for the primary load, e.g., an electric heater, switching circuits responsive to outputs from the primary and back-up loads, and which automatically replace the primary load with the back-up load upon failure of the primary load, said switching circuits including a circuit which reliably reads the output from the primary load and distinguishes failure of the primary load from mere non-load -- including impedance in the primary load circuit, a primary alarm element, e.g. a lamp, bell, or buzzer responsive through said switching circuits to a failure of the primary load and an energizing of the back-up load and a secondary alarm element, e.g. a bell or buzzer responsive to a failure of said back-up element.

Abstract: A hazard prevention control circuit is provided for an electric heater having heating coils enclosed in a quartz tube immersed in a tank of solution. A circuit breaker is connected in series with a contactor coil controlling a set of contacts connecting the main lines of a power supply to the heating coils of the heater. Upon sensing a hazard condition, the control circuit causes excess current to flow through the circuit breaker to open the circuit and deenergize the contactor coil so as to open the contacts connecting the power to the heating coils. Transformers are provided for coupling power supplied by the main lines to the control circuit and the contactor coil and for coupling the pulse output of the control circuit to trigger a triac which conducts the excess current through the circuit breaker.