Abstract: A network of switches for a multiple channel installation adapted to establish connections each between one of N input ports and one of T output ports includes: a plurality of cords each having a first end connected to a first nodal switch, a second end connected to a second nodal switch and, between said two ends, at least one cord switch; optionally, a plurality of branches which comprise a switch having one pole at most connected to an input port, two poles available for the connection of output ports and one pole connected to a pole of a nodal switch; and a plurality of nodal switches interconnected by cords, the input and output ports being connected to the available poles of the switches of the network.

Abstract: An arrangement for terminating a tap-off line (40) between a bus line (14) and a bi-directional signal driver (38). The arrangement includes a resistor (42) serially connected in the tap-off line and a controllable switch (44) connected across the resistor. There is also provided means (46, 48) for controlling the switch to bypass the resistor when the bi-directional signal driver transmits signals to the bus.

Abstract: A microprocessor based uninterruptible power supply generates an AC electrical output power from an AC input source when the AC input source is within settable voltage limits and from an auxiliary source of DC power when the AC input source is outside said the voltage limits. The microprocessor provides monitoring of the AC input voltage to determine its amplitude and frequency, and uses this information to set the magnitude and frequency of the AC output voltage and to select the source of the AC output power. A power factor improvement circuit boosts the selected source to a high DC voltage which is inverted by a chopper circuit to produce a high frequency AC voltage is rectified and sent to a PWM inverter to produce the AC output power. An average current feedback loop provides the output voltage regulation and utilizes current limiting to provide output current limiting for protection against short circuits and overloads.

Abstract: An uninterruptible power supply for supplying a load with AC output power generates the AC output power from an AC input source when the AC input source is within settable voltage limits and transfers to generating the AC output power from an auxiliary source of DC power when the AC input source is outside the voltage limits. A microprocessor provides monitoring and sampling of the AC input voltage to determine its amplitude and frequency, and uses this information to set the magnitude and frequency of the AC output voltage by generating a sine reference signal to control the AC output frequency and voltage phase angle. The microprocessor maintains a voltage phase relationship between the AC input power and AC output power to eliminate voltage and current transients at transfer times between the AC and DC input sources that would be present if the AC output suddenly had a drastic, voltage phase angle change.

Abstract: A delay-on-break circuit adaptable for A.C. or D.C. applications utilizes a timer and a pair of comparators to prevent a load from being re-energized until at least a predetermined period of time has elapsed since the most recent deenergization of the load. A feedback element, such as a zener diode, connected between the output of one of the comparators and a feedback input thereof provides reliable latching of the load through zero crossings of the line in A.C. applications without use of a latching capacitor while simultaneously providing brownout protection capable of rapidly deenergizing the load in the event of an undesired decrease in line voltage.

Abstract: A foot pedal safety switch and safety circuit for industrial machines which effectively precludes accidental operation of a machine and improper repetitive cycling of a machine. The foot pedal is completely enclosed within a rigid enclosure having an entry door through which an operator's foot is inserted each time the foot pedal switch is actuated. The safety circuit includes one or more limit switches indicating the status of the access panel and triggering a timing circuit which provides a time period within which the foot pedal switch must be contacted to operate the machine. For a second operation of the machine, the operator's foot must be removed from the enclosure allowing the access panel to close. To repeat operation of the machine, the operator then places his foot again in the foot pedal through the access panel. The safety circuit is mounted within the foot pedal switch enclosure to provide a self-contained single-actuation device which can be easily incorporated into existing machinery.

Abstract: In response to the loss of a generator in an electrical power system, all operating electrical loads are automatically switched to a second generator, and the electric power system continues to provide power to all of the loads. The total power required to operate all operating loads is permitted to exceed the nominal rated capacity of the operating generator, and the winding temperature or other critical hotspot temperature of the operating generator is monitored to determine whether thermal stress limits will be exceeded. If the critical hotspot temperature approaches the thermal stress limit, certain electrical loads are disconnected via a pre-programmed load shed priority schedule, and thereafter loads are re-connected as other loads are de-energized or if the critical hotspot temperature decreases.