Did You Know...
...that while attempting to develop a super strong glue, 3M employee Spencer Silver accidentally developed a glue that was so weak it would barely hold two pieces of paper together? However, his colleague Art Fry needed the glue. Fry sang with his church choir and marked the pages of his hymnal with small scraps of paper that often fell out. He used Silver's glue to hold the papers in place. Today we call this invention Post-it Notes.
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| Number | Title | Issue Date |
| 5946172 | Installation for power transmission by means of high-voltage direct current, comprising device for detection of a permanent ground fault An installation for power transmission by high-voltage direct current has at least two converter stations which are interconnected by a dc line (DC), at least one station (SR1) having a line protection device (LP) adapted to detect a ground fault on the d... | 08/31/1999 |
| 5936817 | Electrical switching apparatus employing a circuit for selectively enabling and disabling a close actuator mechanism A circuit breaker includes separable contacts for movement between a closed position and an open position, and an operating mechanism for moving the separable contacts between the closed and open positions. Current transformers and potential transformers ... | 08/10/1999 |
| 5805400 | Auto-reclosing dead time control apparatus and method thereof for transmission cable protection relay system An improved auto-reclosing dead time control apparatus and a method thereof for a transmission cable protection relay system which is capable of providing an on-line stability evaluation method which is capable of controlling the dead time of the transmis... | 09/08/1998 |
| 5663712 | Electrical contact position indicator assembly An electrical contact position indicator assembly is operatively coupled to an electrical device, such as a recloser, for indicating the relative position of the contacts of the electrical device, i.e., opened or closed, at any given time during operation... | 09/02/1997 |
| 5631798 | Modular accessory mechanical lock-out mechanism A combined bell alarm and lock-out accessory is connected with the electronic trip unit that controls a high ampere rated circuit breaker. The accessory interacts with the circuit breaker operating mechanism to activate the bell alarm upon circuit interru... | 05/20/1997 |
| 5543669 | Remote feed circuit in communication systems In communication systems, a dc voltage source can be connected via a first and a second winding of an input transformer and a subscriber line to every communication terminal equipment device by using an electronic switch. In case of an overload, the turn-... | 08/06/1996 |
| 5452172 | Auto-reclosers An auto-recloser circuit-breaker has three vacuum interrupters driven from a single bistable magnetic actuator which is powered by a first lithium sulphur dioxide battery under control of an electronic protection relay which is powered by a second lithium... | 09/19/1995 |
| 5400206 | Short circuit and overload protection circuit which allows a predetermined number of reconnection attempts An overcurrent protection circuit is provided with a counter which permits a preselected number of reinitiations of current following the detection of an overcurrent condition. Each stoppage of current in response to the detection of an overcurrent condit... | 03/21/1995 |
| 5396395 | Controller for electric power distribution apparatus Object of the present invention is to provide a controller for distribution apparatus which prevents extension of power failure. In accordance with the controller for distribution apparatus related to the present invention, when a short circuit accident, for e... | 03/07/1995 |
| 5381295 | Resetable battery drain limitation circuit with improved latching relay A battery drain limitation circuit, for use in engine-powered vehicles and equipment that rely on a battery for starting the engine and for operating accessories, disconnects the battery from all loads when the battery voltage falls to a level below which... | 01/10/1995 |
| 5357394 | Circuit breaker with selective locking The electronic trip device comprises a device for selecting the faults which are to bring about locking of the circuit breaker contacts in the open position. When a fault in the power supply system protected by the circuit breaker leads to a trip, the tri... | 10/18/1994 |
| 5103364 | Recloser apparatus A recloser apparatus is provided with an enclosure or tank (40) in which a current interrupter assembly (49) is disposed that includes a pair of relatively movable contacts (50, 54) movable between a closed, current-carrying position and an open, current-... | 04/07/1992 |
| 5099382 | Electrical recloser having external mounting arrangement for electronics assembly An electrical recloser apparatus includes a tank (10) having bottom, top and side walls (18, 22, 16) which define an interior, sealed space (14), and a current interrupter (44) disposed within the sealed space (14) and including a pair of relatively movab... | 03/24/1992 |
| 4974112 | Apparatus for improved protection against lower magnitude faults in an electrical power distribution system Apparatus for improving the performance of conventional electromagnetic reclosing relays under continuous lower magnitude ground or phase faults in electrical power distribution systems. An incomplete sequence relay is connected to the reclosing relay to ... | 11/27/1990 |
| 4899247 | Auto recloser coil burn-out protection An auto-recloser for a power line has a high voltage closing coil (12) for closing the main contact (14) in the power line, the closing coil being energized via a non-latching switching (18) in turn controlled by a low voltage closing coil (20). A time cl... | 02/06/1990 |
| 4857758 | Cycle timer for household appliance A hybrid analog and electronic cycle timer has a mechanical movement and cam-operated cycle switch driven by a low-RPM synchronous motor. Electronic control logic divides the power line frequency to obtain pulses for pulsing the synchronous motor. The con... | 08/15/1989 |
| 4855862 | Recloser undervoltage lockout mechanism In a high voltage circuit interrupter (30) or recloser, an auxiliary undervoltage lockout mechanism (300) provides a backup lockout means to deenergize circuit contactor closing solenoid (78). Auxiliary undervoltage lockout device (300) provides a backup ... | 08/08/1989 |
| 4709292 | Trouble detector apparatus for an air-conditioner including a counter and a timer A trouble detection apparatus for an air conditioner detects overcurrents occurring within a predetermined time period t2 which is a shortest time period necessary for stabilization of the compressor operation. By counting a number of occurrenc... | 11/24/1987 |
| 4608619 | Ground fault voltage limiting for a locomotive electric traction motor The traction motors of a locomotive are voltage limited to a variable extent to permit continued motor operation following the occurrence of moisture induced ground faulting. The heat generated by the continued motor operation dries the moisture which ind... | 08/26/1986 |
| 4604674 | Reclosing relay apparatus A reclosing relay for reclosing a circuit breaker in an electrical power system. The reclosing relay is a multi-shot reclosing relay (i.e., providing more than one reclosure command to the circuit breaker) and includes primary and redundant lockout circui... | 08/05/1986 |
| 4562506 | Distribution line powered switchgear control A distribution line powered switchgear control is provided which reliably initiates switchgear operations with stored energy. Stored energy is preferably maintained in a plurality of devices including a power capacitor. The power capacitor is preferably c... | 12/31/1985 |
| 4477856 | Relay spare circuit for a recloser relay A relay spare circuit for a recloser relay provides an output signal selected to occur during a particular segment of the reclose cycle of a fault-responsive circuit breaker. A set of switches is provided to select which of a plurality of available reclos... | 10/16/1984 |
| 4463401 | Interface circuit apparatus A remotely controlled circuit control device has first and second load contact assemblies movable into circuit engagement and circuit disengagement positions relative to one another in which one load contact assembly is operatively connected to a solenoid... | 07/31/1984 |
| 4316230 | Minimum size, integral, A.C. overload current sensing, remote power controller with reset lockout A reset lockout addition to an A.C. overload current sensing, remote power controller of minimum size and weight and integral construction. Current rate sensing wound toroids are used that are small enough to fit around the line terminal studs without hav... | 02/16/1982 |
| 4241372 | Power supply protective circuit A protective system interposed between a d-c power supply and an external load to isolate the supply from the load should the current drawn therefrom exceed a predetermined threshold value, the system distinguishing between a transitory overload and a con... | 12/23/1980 |
| 4185208 | Anti-pump circuit breaker The circuit breaker is taught with an anti-pumping control circuit. If the circuit breaker closes on a fault and quickly reopens without the closing switch being either mechanically or electrically released in the interim, reclosure of the circuit breaker... | 01/22/1980 |
| 4084204 | Automatic recycle circuit An automatic recycle circuit is disclosed for use in a process or apparatus of the type wherein process or equipment conditions are monitored to detect an abnormal condition. The automatic recycle circuit accepts inputs from monitor circuits which are int... | 04/11/1978 |
| 4042967 | Ground fault sensor An improved ground fault tester uses a magnetostrictive element or piezo-electric element, such as a multimorph, which changes dimensions upon being magnetized or electrically charged. The dimensional change is used to interrupt the power circuit in which... | 08/16/1977 |
| 3940663 | Drive circuit for a main contactor A drive circuit for a main contactor which opens the contactor when a voltage dip occurs and if the voltage dip is of short duration closes the contactor again but blocks reclosing if the voltage dip persists. The circuit includes means to form an undervo... | 02/24/1976 |
