Abstract: A proximity switch is connected to close a circuit between a source and a load when a metal object is adjacent to a coil in the switch. The coil is part of an oscillator circuit that is selected to have its output damped below a selected amplitude when the metal object is close enough to the coil. The reduced amplitude of oscillation opens a capacitor shunting switch thereby permitting the capacitor to be charged. The charging of the capacitor to a selected level turns on an SCR to connect the load to the source through the SCR. A power storage circuit has a capacitor that is charged when the SCR is turned off to provide operating current for the circuits of the switch when it is not available because the SCR is turned on to shunt the current from the main power source.

Abstract: A digital welder control system for controlling a portable gun welder of the type used in the automotive industry on an assembly line. An 8 bit microprocessor is the main control element of the system. The known cycle time of the microprocessor is used to generate a real time delay which in turn is used to generate a digital phase shift heat control. RAM locations in the microprocessor are used to store medium constants of the welding sequence which were previously stored, in prior art controls, in the position of tap switches or thumbwheel switches. The controller provides diagnostics for six common problems often encountered by welder control systems such as override timeout, half cycling, transformer temperature rises, a low water flow, a shorted SCR, and a change in the heat settings. The controller also provides a maintenance interval counter and compensator control having a four-step stepper.

Abstract: A demand controller for connecting and disconnecting loads from a power source has a plurality of control elements in two priority groups, an equal priority group and a set priority group. Loads are controlled by the control elements to be connected and disconnected. A control means directs signals for restoring and shedding the loads and for the priority between the two groups of control elements.

Abstract: A circuit for sensing the motor stator voltage on any one or more phases of an AC electrical drive system. In a three phase system, all three phases of the motor terminal voltage are applied to a modified six-pulse rectifier bridge which in turn feeds a loading resistor. A resistor is added in series with each diode pair of the six-pulse rectifier bridge in order to provide any degree of attenuation of the peak voltage developed across the load resistor by simply varying the resistance values of these series input resistors and the load resistor. The resulting DC voltage generated across the load resistor is then fed into a differential amplifier (stage) where the voltage is attenuated and impedance isolated from the source to provide a DC output which is proportional to the average applied AC motor stator voltage.

Abstract: An apparatus for rejecting an improperly installed plug-on unit, including a circuit controlling device, in an electric power distribution and metering system having a box-like enclosure. A pair of supports are attached to opposing sides within the enclosure with top surfaces substantially parallel to the back of the enclosure so that the plug-on unit can be secured thereto. The circuit controlling device includes a circuit breaker with plug-on jaws, a receptacle and a neutral connector at one end of the plug-on unit which plugs into a jaw of a ground assembly on the back of the enclosure. A plurality of U-shaped interference brackets are welded across the width of the enclosure above the top surface of one support where the end of the plug-on unit containing the neutral connector must be mounted. Each bracket includes a 30.degree.

Abstract: The selector switch has two operating positions, indicated by different colors of light. An operator knob having two spaced translucent portions of different colors is drivingly connected to a tubular switch operator rotor. A lamp shield is received within the rotor around a lamp. The lamp shield has an aperture which directs light only through the translucent portion of the selector switch knob directly over the aperture so that the color of the visible light corresponds to a particular operating position of the selector switch knob.

Abstract: Lengths of lay-in ducts, each in the form of an open top trough having exterior connecting flanges at its ends, are connected together in end to end relation in a run by bolts passed through the flanges. Each trough is provided with a cover which terminates a slight distance short of the trough ends. A joint sealing device common to the adjacent end portions of two connected troughs provides a seal between the device itself and the tops of the adjacent end portions of the trough, between the end portions of the covers and their associated troughs, and between the adjacent end portions of the covers themselves. The device extends across the troughs, and has one end hingedly connected to a supporting bracket which, in turn, is clamped fixedly in position on one of the connected trough flanges by one of the connecting bolts connecting the flanges together.