Abstract: A trip indicator circuit for a circuit interrupter of an electric power system, which includes an electromagnetic status indicator, having an indicator which is movable between an indicating position and a non-indicating position, a pulse-actuated set coil for moving the indicator to the indicating position, and a pulse-actuated reset coil for moving the indicator to the non-indicating position. An indicator set circuit for energizing the set coil is connected across the trip coil by an electronic switching device which is rendered conductive by an overcurrent sensing circuit whenever a particular abnormal condition occurs in the electric power system, so that the set coil will be energized only when the circuit interrupter is tripped during the occurrence of the particular abnormal condition. A reset circuit is connected across the closing coil to energize the reset coil each time the circuit interrupter is closed.
Abstract: A circuit for use with double riser elevator call systems having two sets of "up" and "down" elevator hall buttons per floor associated with respective signal lights. It comprises first and second substantially identical subcircuits each comprising a first resistive element in series with a capacitive element, a solid state variable impedance means in series with a unidirectional current conducting device, and connections from said first resistive means and said capacitive means to said variable impedance means. There is also a second resistive means in circuit between the junction of said first resistance means and said capacitance and the junction of said variable impedance means and said unidirectional current conducting device. A third resistance means has a first terminal connected to said latter junction and a second terminal connected to a corresponding second terminal of a corresponding third resistance means of said second subcircuit.
Abstract: A first amplifier measures the instantaneous voltage across a resistor, connected in series with the electromagnet of a solenoid valve, as the current increases following energization of the electromagnet. A second amplifier measures the same voltage and stores the peak value in a capacitor. The two measured voltages are applied to a comparator which detects the difference, and generates an output, when operation of the electromagnet armature causes a transient reduction in the resistor voltage. Initial energization of the electromagnet sets a memory and starts a monostable timing period. The set output of the memory primes one input of an AND gate, the second input being inhibited by the monostable output during timing. If the electromagnet armature operates normally, the comparator output resets the memory and removes the AND gate priming signal prior to completion of the timing period.
Abstract: An indicator is provided for use in a machine, such as an escalator, having a multiplicity of normally closed switches which act to turn off the machine in the event of a machine malfunction, unsafe condition or an inappropriate switch placement. The switches are capable of reclosing but not restarting the machine. The indicator shows which of the switches caused the machine to stop thereby performing a troubleshooting function to allow a repairman to determine immediately which of the various machine systems caused the malfunction or unsafe condition.
Abstract: Operation of a push button, operates an advancement mechanism to index one of a plurality of magnets adjacent to a fixed polarity magnet coupled to electrical switch contacts to thereby actuate the same. Such plurality of magnets are alternately south and north pole magnets for successively attracting and repelling the fixed polarity magnet on the switch plate upon successive operations of the push button. Indicating lamps may be provided on the push button, the lamps being protected and accessible beneath a transparent lid pivoted on the push button.
Abstract: An electric switch arrangement for use as a current supply switching means for a bipolar electric load is disclosed, comprising two switches connected in series with each other and with the load and located on opposite sides of the load. A monitoring equipment is provided for supervising the operation and function of said switches. Said monitoring equipment comprises potential generating means which are arranged, when both said switches are open, to generate at each pole of the load a potential deviating from the potential existing at said pole when anyone of said switches is closed or both said switches are closed, and sensing means which are arranged to sense the potential of at least one of the poles of the load.
Abstract: A status indicating and current limiting circuit includes a pair of lamp filaments connected in parallel to provide a high reliability for status indication of a monitored switch. The circuit indicates the status of the lamps as well as the open or closed status of the switch. In one embodiment, the pair of lamp filaments are serially connected in parallel between a source of current and the switch so that both the lamp filaments emit bright light when the switch is closed. The lamps are also connected to ground potential through a resistive element to maintain current flow through the lamp filaments when the switch is open, the current being at a level just below the current flow necessary to dimly light the filaments. In the event of a failure of one of the filaments, the other filament will begin to emit a dim but visible light even though the monitored switch is open indicating the failure of the one lamp filament.
Abstract: A leak sensor powered directly by the circuit voltage being controlled by the vacuum circuit interrupter and continuously operating while the interrupter is in service. An indicating system is connected to the leak sensor, or sensors, and provides an indication of failure and corrective action to be taken in single phase or multi-phase circuits.