Abstract: An apparatus for measuring charge state of a battery having multiple cells includes a transmitter that is connected to the battery to apply a test signal across the battery. This test signal is preferably a continuous square wave signal having a frequency less than 3 Hz. The test signal alternates between a voltage adequate to charge the battery and a lower voltage, and the charging voltage is retained for a time sufficient to allow a polarization voltage to develop across individual cells. A receiver is connected to the cell to monitor the polarization voltage across a cell as it develops in response to the test signal. This polarization voltage can be monitored for example using a DC voltmeter, or by displaying the voltage versus time waveform. In either case an accurate indication of the state of the charge of the cell is provided.

Abstract: A testing device measures the impedance of secondary cells that form a battery, such as a lead acid battery, while the battery is in a float charge condition and connected to an active electrical load. The impedance measurement is made at a frequency selected to be different from those frequencies otherwise present in the charger-load circuit. A first application of the testing device monitors the battery for a change in impedance that can signal a developing defect in one or more individual cells or intercell connections that can prevent the battery from delivering its stored energy to the load. In a second application, the testing device is used to compare the impedance of individual cells and electrical connections to locate faulty components.

Abstract: An apparatus for locating ground faults on direct current control systems includes a low frequency current generator having a variable output, a Hall-effect current probe for detecting the low frequency current produced by the generator, a filter and amplifier connected to the output of the Hall-effect current probe for identifying and amplifying the low frequency signal and a read-out element connected to the output of the amplifier to indicate the relative magnitude of the low frequency signal. A method for locating ground faults on direct current control system while the system is energized is described.

Abstract: An apparatus for determining the operating condition of capacitors of the type used for power factor correction on electric distribution systems is assembled in two sections. A first power supply device supplies an alternating electric current to a de-energized capacitor without removing it from its installed position and a second power measurement device, utilizing either a split-core Hall-device or a special distributed winding, measures the magnitude of the electric current entering the capacitor being tested.

Abstract: An apparatus for identifying defective substation capacitors includes a variable power supply section for supplying an alternating electric current to a de-energized substation capacitor bank without disconnecting the individually fused capacitor from the capacitor bus and a second power measurement section for measuring the magnitude of the electric current entering the capacitor being tested.

Abstract: An apparatus for determining the operating condition of capacitors of the type used for power factor correction on electric distribution systems is assembled in two sections. A first power supply device supplies an alternating electric current to a de-energized capacitor without removing it from its installed position and a second power measurement device, utilizing a split-core Hall-device, measures the magnitude of the electric current entering the capacitor being tested.