An automatic override circuit is responsive to the magnitude of instantaneous current flow through a monitored conductor to produce an output signal which can actuate a solenoid or a ground fault interrupter to automatically trip a circuit breaker in repsonse to an excursion of current flow which exceeds a predetermined maximum current overhead level. The short circuit protector can automatically override a thermal trip delay and cause the circuit breaker to trip instantly or delay tripping for a prescribed period of short circuit events which exceed the maximum current overload level. In one embodiment, a control signal is generated which actuates a solenoid which is coupled to a thermal magnetic circuit breaker. In an alternative embodiment, the control signal is utilized for automatically triggering a ground fault interrupter. In both embodiments, the power distribution circuit is interrupted in response to a short circuit condition which would otherwise be tolerated during the thermal trip delay of a conventional circuit breaker.

Trip delay override for electrical circuit breakers

The invention relates to an integrated circuit for contactless radiofrequency device connected to a first antenna and to a second antenna designed to receive a radiofrequency signal coming from a reader. According to a main characteristic, the integrated circuit includes a first rectifier circuit and a second rectifier circuit to rectify each radiofrequency signal received from the first antenna and the second antenna, respectively, so as to produce two positive output voltages V1 and V2, the rectifier circuits being mounted in parallel in order to select an output voltage value that corresponds to the maximum voltage value between V1 and V2.

Contactless radiofrequency device featuring several antennas and related antenna selection circuit

Ground fault detectors commonly interconnect secondary windings of the phase current transformers of a source (N1, N2, N3) into a summing circuit. This circuit will produce a zero output when there is no ground fault condition and will produce on a non-zero output if a ground fault condition exists. A problem exists in that a ground fault detector is not easily connected to an existing system. A solution to this problem is an add-on ground fault system including a module (10) readily connected to the distribution line (N4, N5, N6) and to the associated breaker (STS).

Add-on ground fault module

In a power feeding apparatus having pickup coils L1 and L2, a rectifier circuit 4 and output terminals U and V, the relays R1 and R2 are connected between the output side terminals of the rectifier circuit 4 and the output terminals U and V. Whereas a protective circuit (switching control circuit) 6, which is connected to the pickup coils L1 and L2 and the relay coils r1 and r2 to obtain the electric power from the output side terminals of the rectifier circuit 4 in order to carry out ON/OFF control of the relays R1 and R2 corresponding to the voltage at the both ends of the pickup coils L1 and L2, is provide. The power feeding apparatus enables to prevent an overcurrent from flowing through a load, to prevent the circuit elements from being destroyed or burnt out due to an overcurrent generated in the pickup coils or an overvoltage generated in a resonance capacitor, to indicate an occurrence of an abnormality and to control the electric power supply by means of a remote control.

Power feeding apparatus, transporter and transport system

An overcurrent relay circuit has a power supply developed from a test signal representative of the current in the line being monitored. The power supply is a Zener diode and capacitor arrangement connected in series with the load or test resistor. A variable time-current characteristic circuit (or timing plug) is based upon a variable effective capacitance circuit in which the timing capacitor and resistor currents are isolated from, but dependent upon, one another.

Overcurrent relay circuit

An equipment protection system uses a differential transformer to detect ground faults and energizes a shunt trip coil of a circuit breaker solely with energy induced in secondary windings of the differential transformer by the fault current. Uniform time delay is provided regardless of the magnitude of the fault current and means are provided to prevent partial timing out of the time delay circuit at fault currents below the minimum tripping point. The system provides instantaneous tripping of the circuit breaker upon occurrence of large ground fault currents. A switching triac avalanches into conduction upon occurrence of a relatively large ground fault current to protect circuit components from damage while still permitting energization of the shunt trip coil.

Stanback H

Papers

Ground current powered ground fault protector