Apparatus for overcurrent protection of a push-pull amplifier Patent
Overcurrent protecting circuit for push-pull transistor amplifiers
Sikorra, D. J.↗
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Circuit provides overcurrent protection to push-pull amplifier
Circuit in push-pull amplifier limits the current flowing to a predetermined level and provides that overcurrent in one half of the amplifier turns off the other half.
Skorra, D. J.↗
Electrical short circuit and current overload tests on aircraft wiring
The findings of electrical short circuit and current overload tests performed on commercial aircraft wiring are presented. A series of bench-scale tests were conducted to evaluate circuit breaker response to overcurrent and to determine if the wire showed any visible signs of thermal degradation due to overcurrent. Three types of wire used in commercial aircraft were evaluated: MIL-W-22759/34 (150 C rated), MIL-W-81381/12 (200 C rated), and BMS 1360 (260 C rated). A second series of tests evaluated circuit breaker response to short circuits and ticking faults. These tests were also meant to determine if the three test wires behaved differently under these conditions and if a short circuit or ticking fault could start a fire. It is concluded that circuit breakers provided reliable overcurrent protection. Circuit breakers may not protect wire from ticking faults but can protect wire from direct shorts. These tests indicated that the appearance of a wire subjected to a current that totally degrades the insulation looks identical to a wire subjected to a fire; however the 'fire exposed' conductor was more brittle than the conductor degraded by overcurrent. Preliminary testing indicates that direct short circuits are not likely to start a fire. Preliminary testing indicated that direct short circuits do not erode insulation and conductor to the extent that ticking faults did. Circuit breakers may not safeguard against the ignition of flammable materials by ticking faults. The flammability of materials near ticking faults is far more important than the rating of the wire insulation material.
Cahill, Patricia↗
The solid state remote power controller - Its status, use and perspective
Remote power controllers (RPCs) are solid state devices that combine in one unit the capability to perform all the needed functions of load switching, overload protection, and a direct indication of whether the load is on or off. They provide total system protection of equipment and wires. RPCs are designed to be located near the load and communicate control and status information remotely via low level signals of a few milliwatts. The design and operation of the RPC are considered, taking into account the operation of an RPC, the RPC power switch and drive circuits, control and trip circuits, fail-safe devices, and RPC overcurrent protection. Attention is given to the RPC development status, RPC applications, and RPC perspectives.
Sundberg, G. R.↗
Aerospace technology development of three types of solid state remote power controllers for 120VDC with current ratings of five, and thirty amperes, one type having current limiting
The first generation of remote power controllers (RPC) developed included: a 5-ampere design (Type 1), capable of limiting maximum overload current to 15 amperes for .1 sec; and 5-ampere noncurrent (Type 2) and 30-ampere noncurrent (Type 3) limiting designs, both with selectable instant trip levels for high-current overload. Each design provides overcurrent protection through an inverse I squared T trip-out function with an automatic reset option and demonstrates step-applied fault capability with a 4000-ampere surge, fast-risetime (low-inductance) power source. They also meet MIL - STD - 461A specification for electromagnetic interference. The second generation RPCs traded off specification compliance for reduction in cost and complexity for the Type 1 and 2 designs and give comparable or improved performance in most areas. The noncurrent limiting RPC proved to be a more economical and feasible method of overload protection for certain load types.
Baker, D. E.↗
Kilovolt dc solid state remote power controller development
The experience gained in developing and applying solid state power controller (SSPC) technology at high voltage dc (HVDC) potentials and power levels of up to 25 kilowatts is summarized. The HVDC switching devices, power switching concepts, drive circuits, and very fast acting overcurrent protection circuits were analyzed. A 25A bipolar breadboard with Darlington connected switching transistor was built. Fault testing at 900 volts was included. A bipolar transistor packaged breadboard design was developed. Power MOSFET remote power controller (RPC) was designed.
Mitchell, J. T.↗
Space station electrical power distribution analysis using a load flow approach
The space station's electrical power system will evolve and grow in a manner much similar to the present terrestrial electrical power system utilities. The initial baseline reference configuration will contain more than 50 nodes or busses, inverters, transformers, overcurrent protection devices, distribution lines, solar arrays, and/or solar dynamic power generating sources. The system is designed to manage and distribute 75 KW of power single phase or three phase at 20 KHz, and grow to a level of 300 KW steady state, and must be capable of operating at a peak of 450 KW for 5 to 10 min. In order to plan far into the future and keep pace with load growth, a load flow power system analysis approach must be developed and utilized. This method is a well known energy assessment and management tool that is widely used throughout the Electrical Power Utility Industry. The results of a comprehensive evaluation and assessment of an Electrical Distribution System Analysis Program (EDSA) is discussed. Its potential use as an analysis and design tool for the 20 KHz space station electrical power system is addressed.
Emanuel, Ervin M.↗
Functional requirements for an intelligent RPC
An intelligent remote power controller (RPC) based on microcomputer technology can implement advanced functions for the accurate and secure detection of all types of faults on a spaceborne electrical distribution system. The intelligent RPC will implement conventional protection functions such as overcurrent, under-voltage, and ground fault protection. Advanced functions for the detection of soft faults, which cannot presently be detected, can also be implemented. Adaptive overcurrent protection changes overcurrent settings based on connected load. Incipient and high-impedance fault detection provides early detection of arcing conditions to prevent fires, and to clear and reconfigure circuits before soft faults progress to a hard-fault condition. Power electronics techniques can be used to implement fault current limiting to prevent voltage dips during hard faults. It is concluded that these techniques will enhance the overall safety and reliability of the distribution system.
Aucoin, B. M.↗
Power-Switching Circuit
Functions of circuit breakers, meters, and switches combined. Circuit that includes power field-effect transistors (PFET's) provides on/off switching, soft starting, current monitoring, current tripping, and protection against overcurrent for 30-Vdc power supply at normal load currents up to 2 A. Has no moving parts.
Praver, Gerald A.↗
Hard Fault Protection for a Silicon Carbide-Based Aerospace Motor Drive
Due to increasingly high DC link voltages and further advancements in the current density of silicon carbide (SiC) MOSFETs, it has become evident that conventional IGBT protection methods are not sufficient to protect these devices from overcurrent during low-inductance fault events. The use of an air core Rogowski coil topology was explored to see if it could mitigate these hard fault events. The design of this circuit resulted in safe shutdown of a low impedance phase-tophase fault, tested up to DC link voltages of 1 kV.
High Voltage↗
Arc discharge supply component protection circuitry
In a mercury-bombardment ion engine, the discharge supply is a high-current low-voltage one that maintains an arc or discharge inside the engine. In a 30-cm engine the supply provides up to 45 volts at about 13 amperes and is referenced at approximately 1100 volts above ground. Due to the engine discharge characteristics, a very slow feedback control loop is required. A high-speed current limit must be used to protect the components in the power conditioner, a pulse-width-modulated bridge inverter. A high-speed cycle-by-cycle current-limit circuit which allows the inverter to continue running in an overcurrent condition is used to protect it. The high-speed current sensing allows the inverter to be turned off each half cycle before the current in the primary of the inverter exceeds a safe level. This permits the inverter to continue to provide current into a discharge or a fault condition, until the feedback control system can actively control the current.
Ahrens, A. F.↗
High-power ac/dc variable load simulator
Design of medium-power dynamic electrical load simulator has been extended to permit simulation of ac as well as dc loads and to provide for operation at higher power levels. Simulator is internally protected against reverse voltage, overvoltage, overcurrent, and overload conditions.
Joncas, K. P.↗
Fast-acting self-healing metallic fuse.
Description of a fast-acting nonmechanical self-healing mercury fuse capable of protecting a high current circuit or device from overcurrent fault damages. Basically the self-healing fuse consists of two enclosed mercury reservoirs connected by a fine capillary tube filled with mercury that serves as the fusing element. It is pointed out that a better understanding of the energy conversion process involved in the operation of the device could help explore other device configurations (such as a tapering geometry and use of magnetic field to drive the arc into the fuse wall on inductive loads, etc.) and thus extend the range of capabilities for this type of protective device.
Schwartz, F. C.↗
DC isolation and protection system and circuit
A precision analog electronic circuit that is capable of sending accurate signals to an external device that has hostile electric characteristics, including the presence of very large common mode voltages. The circuit is also capable of surviving applications of normal mode overvoltages of up to 120 VAC/VDC for unlimited periods of time without damage or degradation. First, the circuit isolates the DC signal output from the computer. Means are then provided for amplifying the isolated DC signal. Further means are provided for stabilizing and protecting the isolating and amplifying means, and the isolated and amplified DC signal which is output to the external device, against overvoltages and overcurrents.
Wagner, Charles A.↗