Abstract: In the self testing refrigerator disclosed, a controller normally controls the operation of various electrical devices, such as a compressor, a blower, and an electric heater by actuating and deactuating separate relays from the power source to each of the devices. During self testing, a switch arrangement disconnects the power source supply and substitutes a high voltage dc generator having a series resistor. The same controller that controls the refrigeration operation of the devices automatically actuates the aforementioned relays separately and successively to apply the high voltage across the terminals of the electric devices and ground. The voltage across the resistor indicates the current flow through, and hence the integrity of, the insulation in each of the devices.

Abstract: A direct current fan's status is monitored electronically using a current monitoring circuit. Normally, when a fan is running it exhibits a pulsating current input. The resulting alternating current signal is monitored via the current monitoring circuit to detect whether the fan is running or not.

Abstract: An apparatus and method for testing the ignition modules of gas burners is disclosed, and functions without the requirement of a gas feed in the test program. The method involves disconnecting the ignition module from the electrical supply, and from the gas feed, and employing the apparatus of the invention to apply a test voltage to the ignition module, and to various individual components of the system such as the pilot gas valve and main gas valve which are encased in the gas valve, connecting wires, etc. In order to avoid employing gas feed in the test, a simulated gas flame signal is fed to the ignition module under test using a flame simulator device which sends an appropriate signal to the ignitor module. Hence, with the gas feed disconnected, the test method and apparatus of this invention can be used to conduct the test safely, while saving time, and providing a reliable result.

Abstract: A method and circuit for monitoring phase voltages of a polyphase tachometer generator to detect a phase failure, where the tachometer generator is associated with a rotor position transmitter. The phase voltages are added up by a summing stage to form an auxiliary voltage. The auxiliary voltage is sampled at every commutation instant determined by a rotor position signal generated by the rotor position transmitter during a predetermined measuring time. This sampled voltage value is compared with a predetermined voltage value range. An indication of a tachometer fault is displayed as soon as a sampled voltage value is outside the predetermined voltage value range. By this method and circuit, a fault which occurs between two commutation instants can be detected at the next commutation instant.

Abstract: A method and apparatus for determining the existence of an undesired connection between an electrical system and a desired single-point ground. The electrical system is first disconnected from the desired single-point ground, and is connected to the center point of a resistive divider connected to an isolated voltage source. The voltage of the center point of the resistive divider is monitored and an indication is provided if the monitored voltage indicates the existence of undesired ground paths. The invention also includes elements for measuring the resistance value of a detected undesired ground path, thereby facilitating identification and removal thereof. The invention also includes a voltage clamp which is placed between the electrical system and the desired single-point ground when the electrical system is disconnected from the single-point ground.

Abstract: A portable bar-to-bar armature tester for testing motor armatures for adequacy of their coil windings is disclosed. The tester is to be held by hand, such that four electrical probes, which extend out of the forward end of the tester, contact with four adjacent commutator bars of the armature to be tested. The tester includes a voltmeter in circuit with two of the four probes, and a toggle switch, a rheostat and a D.C. source in circuit with the two other of the four probes. The circuitry is all housed in a hard plastic casing to protect the circuitry from electrical contact with other objects and to protect the circuitry from damage due to dropping or dirt accumulation. The four electrical probes are laterally adjustable and are contacted with four adjacent commutator bars to determine whether the coil windings, are unbroken and properly wound.

Abstract: A simple inspection device is constituted for inspection of an analyzer for measuring ionic activity by using an ionic activity measuring device provided with at least one ion selective electrode pair for generating potential corresponding to ionic activity fo a predetermined ion, and a porous bridge for associating the electrodes of the ion selective electrode pair with each other, and by contacting potential difference measuring probes respectively with the electrodes of the ion selective electrode pair, thereby to measure a difference in potential between the electrodes. The simple inspection device comprises a supporting member having outer dimensions approximately equal to ther outer dimensions of the ionic activity measuring device, and an electrically conductive member supported on the supporting member for short-circuiting across the potential difference measuring probes when the potential difference measuring probes are contacted with the electrically conductive member.

Abstract: A method and apparatus for testing three wire handheld soldering irons by touching the iron's tip to a single point sensor to measure (1) tip temperature (2), tip voltage to ground and (3) tip resistance to ground.

Abstract: A generator for subjecting an electrical apparatus to a surge voltage. The generator includes a surge voltage generator, a line isolation surge filter, wave shaping circuits and a rectifier coupling network for coupling the surge voltages in shunt with the power line and the equipment under test.

Abstract: A method and apparatus for detecting system failure in a magnetron power supply circuit. The apparatus is capable of providing an indication as to whether it is the power supply or the magnetron which has failed. A dual half wave doubler power supply circuit is provided and the currents corresponding to the respective dual portions are measured. The currents are compared to detect a failure of one of the dual power supply circuits while a sum of the currents may detect a failure of the magnetron.

Abstract: In a ground circuit apparatus for electronic equipment according to this invention, a motor driving circuit group constituted of a drum motor, a loading motor and a capstan motor is connected with a DC power source through a power source line and a ground line to have power supplied therefrom. A signal processing circuit group constituted of a camera circuit, a logic circuit, servo circuit, video circuit and an audio circuit as well as an electronic view finder is connected with the DC power source through the power line and a ground line. A video circuit of the signal processing circuit group is connected through a ground line to a chassis which serves as a reference potential point. In addition, two diodes connected in parallel and directed in mutually opposite directions to have opposite polarities and a ground line are connected between the electronic view finder and the chassis.

Abstract: A system for detecting and locating a ground fault (34) in the field winding (2) of a machine, in which a DC potential is present across the winding (2) during machine operation and the winding (2) is normally insulated from ground, the system including: a voltage divider (4) connectable in parallel with the winding (2) and having a plurality of tap points spaced apart along the divider (4); a plurality of current paths (6, 8, 14) each connected between a respective tap and a ground connection point (16); a current detector (12) connected in the current paths (6, 8, 14) for providing an indication of the magnitude of current flowing through each path (6, 8, 14); and signal processing circuitry (20, 22, 24) connected to the current detector (12) for providing an indication of the occurrence of a current flow magnitude associated with a ground fault (34) in the field winding (2) and an indication of at least the approximate location of the ground fault (34 ) along the winding (2).

Abstract: A simple inspection device is constituted for inspection of an analyzer for measuring ionic activity by using an ionic activity measuring device provided with at least one ion selective electrode pair for generating an electrical potential corresponding to ionic activity of a predetermined ion, and a porous bridge for associating the electrodes of the ion selective electrode pair with each other, and by contacting potential difference measuring probes respectively with the electrodes of the ion selective electrode pair, to thereby measure a difference in potential between the electrodes. The simple inspection device employs a supporting member having outer dimensions approximately equal to the outer dimensions of the ionic activity measuring device, and an electrically conductive member supported on the supporting member for short-circuiting across the potential difference measuring probes when the potential difference measuring probes are contacted with the electrically conductive member.

Abstract: A method for partial discharge detection and breaking spark measurement in a dynamo-electric high-voltage machine, especially for monitoring insulation status during operation of a stator winding and connected electrical output lines in a turbo-generator. The generator includes a stator having a stator winding and a stator housing, a rotor with an exciter winding and a shaft, defining an air gap between the rotor and the stator. At least one oil lubricated slide bearing supports the shaft of the rotor with a bearing shell being electrically insulated from the ground. The method includes decoupling the frequency spectrum of high-frequency electromagnetic oscillations resulting from the occurrence of partial discharges or breaking sparks and delivering the frequency spectrum of high-frequency electromagnetic oscillations to a partial discharge measurement apparatus.

Abstract: An inexpensive circuit monitors the resistance between a body (e.g., a static dissipative work surface, a tool, etc.) and ground potential, and compares that resistance with high and low resistance values defining a preset resistance range. An operational amplifier is connected to the body and causes current to flow from the body and through the op amp feedback network. A switching arrangement coupled to the operational amplifier alternately switches the amplifier feedback network between low and high resistance values defining lower and upper ends, respectively, of the preset resistance range.