Abstract: The operating condition and/or characteristics of a battery is tested by obtaining the dynamic voltage-current characteristic of the battery as a function of the charge condition thereof. A controllably varying charging current is supplied to the battery, and the voltage produced across the battery while that current is supplied is measured. The dynamic voltage-current characteristic is obtained as a function of the measured voltage and supplied current. This voltage-current characteristic is compared to predetermined voltage-current characteristics representing batteries of the type being tested in order to determine the operating condition and/or characteristics of the battery under test.

Abstract: A battery is charged by repeatedly alternating between test and charge cycles. During the test cycle, the dynamic voltage-current characteristic of the battery is obtained as a function of the charge condition of the battery. During the charge cycle, a gradually varying voltage is supplied to the battery, substantially without controlling the current supplied thereto, for a predetermined time. The rate at which this supplied voltage varies is related to the dynamic voltage-current characteristic obtained during the test cycle. Alternating between test and charge cycles continues until the dynamic voltage-current characteristic last obtained is substantially identical to the preceding dynamic voltage-current characteristic, whereupon the charging of the battery is terminated.

Abstract: A control circuit for use with a shuttle car used in mining operations and circuitry associated therewith. The control circuit generally comprises a chopper circuit in series with a reversing circuit and a traction motor which drives the shuttle car. The chopper circuit essentially comprises two separate current paths each through a separate set of silicon controlled rectifiers or SCRs and a common capacitor. A logic circuit controlled by the operator alternately gates the sets of SCRs thereby placing voltage across the traction motor. The magnitude of this voltage and hence the speed of the motor are directly proportional to the frequency of the gating pulses. The reversing section also employs two sets of SCRs and a common field inductance. The operator, through the logic circuit, triggers one set of SCRs and current flows through the field inductance in a forward direction causing the traction motor to operate in a forward mode.

Abstract: A power circuit for use in billet heating, surface heat treating and melting and protective circuitry associated therewith. The power circuit generally comprises a source of potential in series with a pair of inductances and an inverter module. The inverter module has two sections each comprised of a thyristor in parallel with a diode. A pair of series connected charging capacitors are connected across the source of potential and a load is connected from between the capacitors to between the two sections of the inverter module. Current flows through one thyristor, through the load and charges the capacitors. The capacitors discharge and a reverse current flows through the load and through the corresponding diode. This cycle is repeated then with the opposite section of the inverter module. A commutation failure protection circuit is provided which detects the voltage collapse condition accompanying a short circuit through the inverter module and when this occurs, it acts to shut off the thyristors.