Abstract: A capacitive power supply having a charge equalization circuit. The charge equalization circuit is comprised of a shunt circuit connected in a parallel connection with capacitive elements of the capacitive power supply. Once a charging current is applied to the capacitive power supply to store charge thereupon to form thereby a potential difference across the capacitive elements of a pre-determined level, the shunt circuit forms a shunt to shunt the charging current thereto.

Abstract: A power supply incorporating a fault detection circuit controlling a circuit breaker is described. The power supply is isolated from relatively large applied DC voltages. This isolation is provided by a coupling capacitor in each of the line leads. The tripping energy for the circuit breaker can be provided either directly from the full wave rectifier output, or directly from the line lead or leads. In the case of the former, a reservoir capacitor may be used for storage of charge for tripping of the circuit breaker.

Abstract: A device which enables a self-healing capacitor with more than one group of sections in series to undergo repetitive clearing without generating the resulting potential differences between the series sections which causes additional failures. In one embodiment, the device to conduct charge is a diode and resistor connected across each group of parallel sections so as to be nonconducting when the capacitor is charged but to become conducting when a clearing event occurs. An additional aspect of the device is a method for charging such a capacitor so that no section is overcharged.

Abstract: A device to locate internal faults in a high-voltage capacitor battery that has a plurality of symmetrically parallel and series-coupled capacitor banks arranged in parallel branches coupled by shunt branches. The phase angles of the shunt currents flowing in the shunt branches relative to the total current flowing in the parallel branches are determined. A fault is located in one of the capacitor banks based upon these determined phase angles.

Abstract: A capacitor protection circuit for protecting bulk storage capacitors in a storage capacitor circuit in an electronic power supply. The capacitor protection circuit is operatively coupled to the storage capacitor circuit and comprises a first and second thyristor. The first and second thyristors are selected so that when the voltage across one of the storage capacitors in the storage capacitor circuit exceeds a predetermined voltage, the second thyristor will trigger the first thyristor to cause an excessive amount of current to be drawn through a fuse in the electronic power supply, thereby causing the fuse to blow and uncoupling the electronic circuit from an AC input. Another embodiment is disclosed to show how the capacitor protection circuit can be used in a 110 or 220 volt environment by utilizing a switch.

Abstract: Series capacitor equipment for distribution networks has a capacitor, voltage-dependent resistors as over-voltage protective means for the capacitor, a mechanical high-speed circuit-closer and a switch connected in parallel with the high-speed circuit-closer, for bypassing the equipment. At an overcurrent in the power line, tripping members initiate closing of the high-speed circuit-closer, which closes rapidly sufficient to protect the resistors against overload, and of the switch, which relieves the high-speed circuit-closer. The high-speed circuit-closer, the switch and the tripping members are mounted in a grounded cubicle.

Abstract: Series capacitor equipment is connected into an electric power transmission line (L) and has a capacitor bank with a first part (CO) series-connected with a second part (C1-Cn) with variable capacitance. For protection against overvoltages, a first spark gap protective means (GO, T, TE) is connected across the first part, and a second spark gap protective means, connected in series with said first spark gap protective means, is connected across the second part of the bank. The point of connection (A) of the spark gap protective means is connected to the point of connection (B) of the bank parts through a resistor (R). The first spark gap protection means is adapted to be ignited at a predeternined level of the current in the power transmission line, the voltage drop across the resistor (R) then causing said second spark protective means (G) to become ignited.

Abstract: A trigger circuit for a spark gap chain with at least two series-connected spark gaps, of which at least one is provided with at least one trigger electrode, includes a resistor chain which is connected in parallel with the spark gap chain and comprises at least two series-connected resistor groups. That of the resistor groups which is connected in parallel with the spark gap provided with a trigger electrode comprises a voltage-dependent resistor, built up of zinc oxide varistors, which is connected in series with a linear resistor. The voltage across the linear resistor is supplied to the trigger electrode of the spark gap for ignition of the spark gap when this voltage amounts to a pre-determined value. The spark gaps are primarily intended to be utilized for overvoltage protection of series capacitors.

Abstract: A fault detector for detecting faults in a DC capacitor circuit connected to the DC buses of an inverter circuit using semiconductor device for converting direct current into alternating current to suppress the voltage pulsation and comprising a plurality of parallel-connected capacitor circuits each having a plurality of series-connected DC capacitors. The fault detector comprises a comparison means connected to the junctions of the series-connected DC capacitors to compare the respective potentials of the parallel-connected capacitor circuits, and detects the short-circuit and time-aging of the DC capacitors of the parallel-connected capacitor circuits rapidly on the basis of the output signal of the comparison means.

Abstract: A geometric arrangement for filter capacitors used in high frequency power supplies such that a multiplicity of paralleled capacitors not only share the current but also provide optimum filtering. The terminals of each of the capacitors are connected by equal inductances to receive the rectified alternating current. The capacitor terminals are also connected directly to the output of the supply in order to provide the D.C. current thereto.

Abstract: As overvoltage protection for a series capacitor (C1-C5) in a high-voltage network a voltage-dependent resistor (Z6), built up of metal oxide varistors, is arranged in parallel with the capacitor. In parallel with the resistor there is a spark gap means consisting of two series-connected spark gaps (G1, G2) for shunting the resistor in case of overload thereof. The energy for triggering the spark gap means is obtained from an auxiliary capacitor (C5), which is charged during operation, and is supplied to one of the spark gaps (G2) via a switching means (T1, T2), controlled by an overload detector (CU), and a pulse transformer (TR). A metal oxide varistor (Z5) is connected in series with the high voltage winding of the transformer. The transformer is connected so that the triggering pulse is in opposition to the voltage across the series capacitor.

Abstract: A series capacitor bank for connection into an electric power supply network is provided with overvoltage protective equipment having two branches connected in parallel with the capacitor bank. The first branch comprises a first zinc oxide varistor in series with a linear resistor and the second branch comprises a varistor with a higher "knee" voltage than the first zinc oxide varistor. The resistance of the linear resistor is preferably of the same order of magnitude as the absolute value of the impedance of the capacitor bank at the operating frequency of the power supply network. The "knee" voltage of the second varistor is at least 1.15 times (and preferably not more than 2.0 times) the "knee" voltage of the first varistor.

Abstract: A linear resistor is serially connected to a voltage-dependent metal oxide varistor and the series-connected resistor elements are connected in parallel with the series capacitor of a high voltage network to provide an overvoltage protection circuit for the series capacitor. A spark gap is also connected in parallel with the series-connected resistor elements in case of overload thereof. The voltage across the linear resistor triggers device for firing the spark gap when the voltage across the linear resistor exceeds a predetermined voltage. The resistance of the linear resistor and that of the varistor is dimensioned such that the predetermined voltage constitutes the smaller part of the voltage across the capacitor.

Abstract: A non-linear resistor assembly protecting equipment such as series capacitors is itself protected by a bypass spark gap, the firing of which is produced by a digitized pulse train, each pulse of which indicates a known increment of energy input to the varistors and is processed by counters and logic gates to achieve an initiating firing pulse upon the occurrence of a predetermined number of pulses indicating the energy input has reached predetermined limits within a given time period. The initial firing pulse is further processed through stages including semiconductor device switching, trigger spark gap firing and energy dumping from an energy storage capacitor into the elements of the main bypass spark gap.

Abstract: A protective means for a series capacitor in a high-voltage network comprises a voltage-dependent resistor (varistor) arranged in parallel with the series capacitor, a spark gap arranged in parallel with the varistor for shunting the latter when it becomes overloaded, a current-sensing member, for example a current transformer, for sensing the current through the varistor, an energy absorption detector for sensing the temperature of the varistor, and a pulse transformer electrically or magnetically connected to the current-sensing member, for triggering the spark gap. During normal operation of the network and the series capacitor the current-sensing member is short-circuited by a normally closed switching device.

Abstract: An individual capacitor unit has an individual discharge damping circuit, which may be contained within the unit housing, that is connected between a capacitor stack connection and a terminal of the unit. The damping device includes a predominantly resistive circuit path in parallel with a predominantly inductive circuit path.

Abstract: Electrical equipment protection apparatus is provided comprising a plurality of varistor devices connected mutually in parallel, each of which exhibits a non-linear characteristic with an inherent differential in such characteristics, in combination with current sharing elements comprising a plurality of positive temperature coefficient resistors respectively associated with each of the non-linear resistors to ensure substantially equal current sharing among the plurality of varistors.

Abstract: A capacitive voltage transformer of the type having voltage divider capacitors and an electronic amplifier connected to one of the divider capacitors includes circuitry for isolating the voltage divider capacitors in the event that primary power to the voltage divider is interrupted. The circuitry measures and compares the voltage at a terminal of one of the divider capacitors and the current through the divider. If primary power to the voltage divider is interrupted, the capacitor voltage remains high while the divider current goes to zero, and the circuitry acts to isolate (such as through relay controlled switches) the divider capacitors from the electronic amplifier. This prevents any distortion from appearing in the voltages across the divider capacitors and prevents transients from developing at the input to the electronic amplifier.

Abstract: A multi-series group capacitor bank has voltage limiters, of the metal oxide type, connected across each individual series group and set at a protection level higher than that of the bank bypass spark gap so the voltage limiters bypass a series group when capacitor fuse clearing causes high voltage build-up in that series group.

Abstract: The invention provides an improved circuit for determining rates of rise of energy in metal oxide varistor devices. A high voltage transformer is employed to trigger a protective air gap for bypassing the metal oxide varistor device. One application for the invention is for use within a series capacitor protective circuit.

Abstract: Where multiple bypass circuits are provided across the protected equipment and have different sensitivity to overvoltages, the more sensitive trigger gap circuit branch is coupled to the high voltage main spark gap by means including a pulse transformer to boost the voltage across the main gap rapidly upon firing of the trigger gap so that the trigger gap can be at a highly sensitive overvoltage level to minimize further any danger of transient mechanical subsynchronous shocks to the rotating shafts of large generators in a transmission system, while retaining the ability of delayed reclosing of the trigger gap branch following its operation to immunize it against post reinsertion transient voltages.

Abstract: The invention provides a circuit for determining excessive energy magnitudes or rates of rise of energy in metal oxide varistor devices. The circuit further provides a series of low voltage control pulses for energizing a high voltage pulse generator. The output of the high voltage pulse generator triggers a protective air gap for bypassing the metal oxide varistor device. One application for the invention is for use within a series capacitor protective circuit.

Abstract: Circuitry for limiting the instantaneous peak current, under fault conditions, of an AC power line, includes a high speed circuit breaker in series with a first capacitor in a main current-carrying branch, which branch is paralleled by two additional branches. According to various embodiments these branches contain various combinations of resistance, capacitance and spark gap elements whereby upon occurrence of the excess fault condition, the high speed circuit breaker opens. Thereafter the voltage buildup across the first series capacitor is sequentially commutated to a second branch having a capacitor and spark gap, with a predetermined arc-over voltage, and subsequently to a third resistive branch. The third branch effectively provides the peak current limiting impedance.

Abstract: An RLC triggering circuit employs an inductance coupled to the trigger electrode of a triggered vacuum gap device. A capacitance and a switch are coupled in series with the inductance. A diode in parallel with the series-coupled capacitance and switch serves to provide a long, unidirectional current pulse to prevent the triggered vacuum gap from chopping current and generating dangerous surge voltages.

Abstract: In a series capacitor transmission system the protective bypass device has a force firing arrangement responsive to an applied signal for causing the series capacitor bank to be bypassed rapidly, such as within three cycles, for reducing subsynchronous oscillation effects on generating equipment connected with the transmission system. A capacitive potential device supplies power to energize a firing control circuit with a pulse transformer placing high frequency or pulse voltage across the protective device for rapid bypassing. The bypass device may be a protective spark gap as is normally present for protection of the capacitor bank against overvoltages.

Abstract: A capacitor bank is provided with a relay protection device having a number of measuring stations for sensing a number of different disturbances associated with the capacitor bank. Each respective primary winding of a number of auxiliary transformers is connected to a respective measuring station. The auxiliary transformers generate signals at the respective secondary windings thereof with each signal having a respective duration and level output for identifying a respective one of the different disturbances. An electrically insulated current transformer transmits output signals representative of the auxiliary transformer signals to a number of sensing relays each having a respective tripping time and signal level response such that the particular disturbance can be identified.

Abstract: Series capacitor blanks are inserted in high-voltage alternating current network systems in order to improve the stability of the system. Such capacitor banks are provided with a shunt-circuit for short-circuiting the capacitors if the voltage across them increases above a predetermined value at which the capacitors may be damaged or destroyed. When, in the event of a disturbance in the network, said shunt-circuit has short-circuited the capacitors, the stabilizing ability of the capacitors is gone. In order to avoid this, the capacitor bank is provided with a further shunt circuit including non-linear resistors, said resistors having a very high resistance as long as the voltage across the capacitor bank is lower than a predetermined value. Said value is higher than the noraml operating voltage of the capacitors but lower than the voltage at which the first shunt circuit short-circuits the capacitor bank.

Abstract: An overvoltage across each of N series capacitors is sensed by an individual overvoltage sensor through an associated current transformer and applied to a central control apparatus. Each capacitor is connected across an electric valve with a trigger electrode and also across a normally open circuit breaker. Another current transformer includes a secondary winding connected to the trigger valve electrode and a primary winding connected across a discharge circuit controlled by the central control apparatus. With an overvoltage developed across any capacitor, the discharge circuit discharges the electric valve and then closes the circuit breaker.