| Patent Number |
Title Of Patent |
Date Issued |
| 6191968 |
Wye connected 3-phase to 9-phase auto-transformer with reduced winding currents |
February 20, 2001 |
| In an 18-pulse converter system a 3-phase to 9-phase auto transformer with multiple windings per phase is used to power a 9-phase AC to DC converter. The transformer kVA rating is typically about 55% of the DC load kW. Multiple delta connected coils formed around a basic wye connected |
| 6101113 |
Transformers for multipulse AC/DC converters |
August 8, 2000 |
| In a 12-pulse converter system a 3-phase auto transformer with 4 windings per phase is used to power two 6-pulse converter bridges connected in parallel with a large dc filter capacitor. The transformer rating is typically about 40% of the dc kW load. The voltage ratio is typically 1:1 |
| 5781428 |
Transformer for 12-pulse series connection of converters |
July 14, 1998 |
| In a multi-pulse converter system a three-phase transformer with tapped wye-connected primary winding and isolated delta-connected secondary winding is used to power two 6-pulse converter bridges connected in series to give 12-pulse operation. The transformer equivalent kVA rating is a |
| 5455759 |
Symmetrical, phase-shifting, fork transformer |
October 3, 1995 |
| In 12-pulse and 18-pulse AC/DC converter systems a single wye connected auto transformer using appropriate segments of voltage from each phase connected in fork fashion is used to develop 6-phase and 9-phase voltages in a symmetrical manner such that inherent compensation is made for the |
| 5148357 |
Auto-connected hexagon transformer for a 12-pulse converter |
September 15, 1992 |
| A 12-pulse converter of lower rating and minimal current harmonics is obtained with an auto-connected regular hexagon transformer including a delta winding in its center. |
| 5124904 |
Optimized 18-pulse type AC/DC, or DC/AC, converter system |
June 23, 1992 |
| A 18-pulse converter system operates without interphase transformer and neutral point on the DC side by providing three rectifier bridges across the DC terminals, one rectifier bridge being coupled with the AC terminals and the two other rectifier bridges being operated at + and -40 degr |
| 4876634 |
Multi-pulse converter system |
October 24, 1989 |
| In a multiphase AC/DC converter system a single transformer is used having phase shifted tappings drawn from a polygonal succession of long and short windings wherein some of the windings carry only the difference between the outputted currents derived from the tappings. |
| 4719398 |
Coasting AC motor restart system and method |
January 12, 1988 |
| A variable frequency adjustable speed motor drive allows restart of a spinning induction motor by initially increasing the frequency of the associated inverter while keeping the DC voltage source thereof low, then by decreasing the frequency of the inverter while monitoring the effective |
| 4698739 |
12-Pulse motor drive |
October 6, 1987 |
| The present invention relates to an AC motor drive including two sets of inverters, wherein one transformer is converted on the output of one of the two inverters, the output of the transformer being connected in series with the output of the other inverter. |
| 4674024 |
High voltage modular inverter and control system thereof |
June 16, 1987 |
| Low voltage GTO inverter modules are combined to form a high-voltage multi-inverter system by connecting standard modules in a string with isolated DC links. Modular construction is arranged for building multiphase systems. Voltage control is effected by controlling selected modules |
| 4634981 |
Method for testing a circuit breaker using a three terminal current transformer |
January 6, 1987 |
| A method for and an apparatus for use in testing a circuit breaker, the circuit breaker having at least one current sensing means, such as a current transformer, trip circuitry, and circuit interruption means. In the method, a low voltage A.C. source is provided; and means for genera |
| 4618906 |
Hybrid solid state/mechanical switch with failure protection |
October 21, 1986 |
| A hybrid solid state/mechanical switch is provided with a pair of mechanical contacts connected in parallel with a solid state switching device. These components are operated by a control circuit to achieve arcless current interruption under normal conditions. A circuit breaking devi |
| 4463400 |
DC Static switch with phase commutation |
July 31, 1984 |
| An apparatus for the interruption of DC transmission lines without substantial arcing utilizing in combination a DC circuit breaker, a DC-to-AC current converter, converter control and an AC power sink. Upon command from the converter control, DC current is converted to AC current in |
| 4438474 |
Current limiter and VAR generator utilizing a superconducting coil |
March 20, 1984 |
| A current control device which may act as a current limiter and/or a VAR generator through the use of a superconducting inductor is taught. In one of the embodiments of the present invention, a full wave bridge rectifier network is serially inserted in one leg of a high voltage transmiss |
| 4406991 |
High power resonance filters |
September 27, 1983 |
| There is provided by this invention a novel high power resonance filter utilizing a resistive element between two resonant branches disposed to dampen resonant harmonic currents or voltages while maintaining minimal losses at the fundamental frequency. |
| 4296450 |
Discriminating circuit breaker protection system direct current power distribution systems |
October 20, 1981 |
| An improved discriminating circuit breaker system for use with an electrically grounded direct current power distribution system. A three-tier safeguard system is provided to insure proper operation of the breaker should a fault occur. The basic components include the electrically op |
| 4220896 |
High frequency lighting inverter with constant power ballast |
September 2, 1980 |
| A lighting inverter for operating an electrical discharge lamp from a direct current power source. The inverter includes a resonant feedback inverter which converts the output of the d.c. power source to an alternating current output and regulates the a.c. inverter output voltage lev |
| 4209739 |
Portable calibrator for d.c. circuit breakers |
June 24, 1980 |
| A portable calibrator for d.c. circuit breakers is provided which produces a low voltage, short duration current test pulse of a current level sufficient to trip the breaker under test. The current pulse is produced by a high power, high frequency d.c. to d.c. converter which is controll |
| 4165527 |
Current limiting circuit arrangement |
August 21, 1979 |
| A current limiting circuit arrangement is disclosed herein and includes a pair of parallel connected circuits, preferably identical circuits, each of which includes series connected conductive and capacitive reactance tuned to resonate at a given frequency. The arrangement also includes |
| 4083001 |
Measurement of motor winding temperature |
April 4, 1978 |
| The temperature of a motor winding is measured or monitored by measuring the resistance of the winding. This is done by introducing a small direct current component into the motor current, which can be done by connecting an asymmetric resistance device in the motor circuit. The resistanc |
| 4011484 |
Undervoltage release with electrical reset for circuit breaker |
March 8, 1977 |
| An undervoltage circuit having a power supply voltage level detector, a reset circuit, and a hold-in circuit. The level detector of the circuit causes an undervoltage coil to trip a circuit breaker when the power being supplied falls below a predetermined voltage level. When power is |
| 3946279 |
Active impedance multiplier |
March 23, 1976 |
| An active impedance multiplier circuit that can, as one of its uses, be used in a mine ground fault detection system. The purpose of the multiplier is to create a very high impedance for an AC signal that normally flows through a low impedance legitimate load. To accomplish this, the |
