High-voltage Connection Research Articles

Fabrication of a versatile microanalytical system without need for clean room conditions

In this paper, we address the problem of designing microanalytical systems that are easily interfaced to the general laboratory environment (“macro world”) and that do not require any special facilities such as clean rooms for their fabrication. The separation chip is realised in glass, the channels in particular by sawing with a 70 μm resinoid blade. While this restricts us to the fabrication of straight channels, it is much faster and less complex than any other method used at present for channel production in microfluidic chips. In view of a future application in pressure or voltage driven nano-chromatography, a monolithic stationary phase was synthesised in the separation channel of the chip. A multifunctional connection and support unit containing optical probes, reservoirs, as well as high pressure and high voltage connectors, constituted the interface to the macro world. Depending on the procedure used to bond the upper and the lower part of the microfluidic chip (adhesion forces or high temperature bonding) chips inserted in the unit could withstand upper pressure limits of 130 and 150 bar, respectively without leakage or disintegration. The system was then characterised in terms of its fluid dynamics under pressure and voltage driven conditions and its functionality was demonstrated in a preliminary experiment.

Environmental Implications and Potential of International High-Voltage Connections

This paper reviews the potential of international High-Voltage connections and their impact and implications on the environment. It considers the proposed North African Super-grid, ways of creating connections in East Asia, HighVoltage connections in Eastern Europe, together with emissions from different types of power plant, and aspects which are considered in system interconnection feasibility studies. A case study highlighting environmental issues and High-Voltage interconnections considering electromagnetic fields, greenhouse gas emissions, rare and endangered species, and public participation programs in Quebec is summarized. First, the advantages of power system interconnections between the power systems of Algeria and Tunisia, Algeria and Morocco, Tunisia and Libya, and Egypt and Libya, together with the potential of creating a North African Supergrid, are reviewed. The interconnection would be used mainly for reserve sharing, which may result in savings in reserve capacity of more than 12GW in 2015. Then, ways of creating international connections in East Asia and environmental implications of the connections are discussed: specific features of the region, state of the East Asian Electric Utility industry, and proposed main interstate ties in the region, including the Russia-Japan tie, Russia-China-South Korea tie, and East Siberia-China tie. The paper goes on to discuss ecological benefits of HVDC in comparison with HVAC, together with the main environmental advantages of the use of hydro power resources instead of thermal power plants (with their pollution) in the eastern parts of Russia, China, Korea, and Japan. CO 2 emissions from different types of electricity generation power plants in Europe are discussed. Also discussed are the advantages of enlargement of the UCTE system to the CENTREL countries; a five-terminal HVDC project connecting the systems of Russia, Belarus, Poland and Germany; and the building of the Baltic Ring. Environmental, social development, and gender considerations in feasibility studies for High-Voltage interconnections is also discussed, where feasibility study considerations, the identification of essential organizations, identifying guidelines, defining preferred corridors, and the evaluation of costs are among the considerations that are examined. A case study on environmental implications of cross-border power lines created by free trade and regulation in Quebec in which environmental management systems, environmental issues, and advantages and disadvantages of the alternatives are examined is also discussed.

Electrophoresis with electrochemical detection in a polymer microdevice

This work presents the integration of an electrochemical detector in a photoablated polymer microdevice with electroosmotic driven flow. The structure of the device features a separation capillary with two side arms forming the injection capillaries, an electrical decoupler and an electrochemical detector. The decoupler is composed of a microhole or microhole array perpendicular to the separation microchannel. The system allows the electrical high voltage connection between the inlet of the capillary and the decoupler; the remaining end of the separation capillary being almost free of electric field, facilitating an electrochemical detection at the end of the microchannel. Separation parameters have been varied comprising the electrophoretic potential, the time of the injection and the buffer composition. Separation of model phenolic compounds is shown here as a demonstration of the system.

The influence of solder fillet geometry on the occurrence of corona discharge during operation between 400 and 900 V in partial vacuum

A number of experiments have been made to study the effect that different solder joint designs have on the voltage needed to initiate the onset of corona discharge under low ambient pressures. Wires were joined to both printed circuit board terminations and to electrical feedthroughs. All were constructed from materials known to be suitable for spacecraft. The main factor that determines whether solder joints will be prone to initiate corona discharges or electrical breakdown in a space environment is the actual minimum distance between terminals. Large, rounded solder fillets are desirable, but those containing protrusions or contours around wire strands have little adverse effect. It is shown that it is not always necessary, as is usually required by workmanship specifications related to high voltage connections, for operators to rework solder joints in order to achieve protrusion-free fillets. It would appear from metallurgical analyses of solder joints that it is the tin-rich phase that is sputtered from the fillet's surface during the phenomenon of corona discharge.

Environmental Implication and Potential of International High-Voltage Connections

Environmental Implication and Potential of International High-Voltage Connections

Coaxial 30 kV connectors for the RG220/U cable: 20 years of operational experience

The RG220/U cable connector has been used very successfully for 20 years under difficult conditions. Its design principle can be applied to a wide variety of other cable types and voltages. The principle of the tool for machining the cable can be adapted to many different cable types. The main manufacturing difficulty is the execution of the finger contacts to tight tolerances. These contacts must be handled with care and checked individually before assembly. The radiation resistance of Scotchcast/sup R/ 815 is better compared to polyethylene and therefore does not limit the use of this connector design. Finally, the design was successfully adapted to mass production and the price can be compared favorably with a commercial 30 kV connector. For the Large Hadron Collider, two large injection systems and two extraction systems are under construction requiring more than 800 coaxial high-voltage connectors. In view of our very positive experience and the excellent long-term behavior, we conclude that the design of these connectors is also perfectly adapted for the new project.

An electrostatic Si e-gun and a high temperature elemental B source for Si heteroepitaxial growth

In this paper we present two kind of sources used in Si MBE growth: a Si source where an electron beam is electrostatically deflected onto a Si rod and a high temperature B source to be used for p-doping. Both sources have been designed and constructed at IESS. The Si source is constituted of a Si rod mounted on a 3 4″ flange with high-voltage connector. A W filament held at high voltage (up to 2000 V) is heated by direct current. Electrons from the filament are electrostatically focused onto the Si rod which is grounded. This mounting allows a minimum heating dispersion and no contamination, because the only hot objects are the Si rod and the W filament which is mounted in such a way that it cannot see the substrate. Growth rates of 10 Å/min on a substrate at 20 cm from the source have been measured. Auger and LEED have shown no contamination. The B source is constituted of a graphite block heated by direct current. A pyrolitic graphite crucible put in the graphite heater contains the elemental B. The cell is water cooled and contains Ta screens to avoid heat dispersion. It has been tested up to a temperature of 1700°C. P-doped Si 1− x Ge x layers have been grown and B concentration has been measured by SIMS. A good control and reproducibility has been attained.

New Capabilities From High Voltage Connectors

THE trend in high voltage connectors is towards miniaturisation, while providing the same degree of voltage handling and anti‐corona discharge performance as conventional designs. This usage of smaller dimensions is being achieved through careful design of parameters such as the tracking path lengths, scrupulous exclusion of air from the cable, connector internals and the mating surfaces.

Operational characteristics of an electron-bombarded silicon-diode photomultiplier tube

An electron-bombarded silicon-diode photomultiplier tube (EDPMT) has been constructed and the first experimental data on operational characteristics are presented. The signal multiplication of this tube is, in contrast to the traditional PMT, not accomplished by multiplying the number of photo-generated electrons, but by increasing each electron's energy 3–4 orders of magnitude. The relative simplicity of design properties make this type of tube an attractive alternative for many applications. This tube has small size, low mass, it is robust and it incorporates a low cost electron multiplier. Also, it only requires a single negative high voltage connection, without a voltage-divider, and a low voltage diode reverse-bias connection, which greatly reduces the power supply requirements for large scale operations such as those at CERN, Fermilab, and the Superconducting Supercollider.

100 kV Schottky electron gun

We present a comparison between experimental results and computer calculations on a high current, high resolution single lens electrostatic 100 kV Schottky electron gun. One promising application for such an electron gun is for direct electron-beam patterning of x-ray masks. The high energy helps provide precise patterning of the thick resist, maintains vertical resist profiles, and minimizes the proximity effect. The gun was designed to operate from 25 to 100 kV, capable of focus at a distance of 145–245 mm with a magnification of 1.15. The emitter, of apex radius ∼0.6 μm operated at 1800 K in the extended Schottky regime, provides an angular intensity of 0.5 mA/sr for an extraction voltage of 5000 V and with a beam limiting aperture of 2.2 mrad, the gun delivers 7 nA of probe current. The gun consists of a replaceable high voltage optic module mounted on a precision insulator with the main acceleration occurring between the exit of the optic module and the grounded anode. A provision is made for alignment of the emitter with respect to the central optical axis of the optic module in a special alignment chamber eliminating the need for high voltage emitter alignment. Final gun alignment is achieved by X–Y motion of the grounded anode aperture. The gun is constructed to allow ease of replacement of the emitter, the beam defining aperture, and the differential pumping aperture. The beam supply has 10 ppm of ripple while lens supplies have <50 ppm of ripple. At 100 kV the power supply, cabling, connectors, insulator, and optic module draw 1 μA of ground leakage current. Pressured SF6 chambers are used for high voltage connector interfaces within the power supply and on the gun.

A new sensor for detecting partial discharges in operating turbine generators

A partial discharge (PD) sensor has been developed which is able to unequivocally differentiate between PD in the winding and all types of electrical interference. Thus, the sensor will permit an online test for turbine generators, similar to the test now used for hyrogenerators. The sensor requires no high-voltage connection to the winding, and is easily installed in the stator slot, underneath the wedges. Noise is differentiated from PD by the shapes of the electrical pulses from the sensor. The sensor, called the Stator Slot Coupler (SSC), is essentially a directional electromagnetic coupler. Calculations as well as laboratory tests indicate that the couplers can easily survive the electrical, thermal, magnetic, and mechanical stresses in the generator.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Silicon photodiode detector for fluorescence EXAFS

A large-area silicon diode is used as a fluorescence detector for extended x-ray absorption fine-structure (EXAFS) measurements. A direct comparison of this diode detector relative to a gas ionization fluorescence detector is made. Advantages of the diode detector include: higher signal for a given photon flux (due to higher quantum efficiency), vacuum and cryogenic compatibility, freedom from microphonic noise, good linearity, extremely wide dynamic range, operation without high voltage or gas connections, very simple electronics, and low cost. A brief comparison with other detection methods for fluorescence EXAFS is given. Use of photodiodes for transmission EXAFS is discussed.

One Alternate to the Secondary Network and Underground Systems

Equipment is available which provides a single alternative for secondary network and vault services. Recent development of a Front Operable Underground Type Single Phase Distribution Transformer with Separable Insulated High-Voltage Connectors makes possible the use of a single system for vault type installations. Three phase service is obtained by banking these units. This paper describes this type transformer, its operating features, and application. Front operability allows this transformer to be switched employing the same tools and procedures used for padmounted equipment. Comparisons are made between installations using this front operable transformer and ones with alternate equipment.

Separable Connectors for Large Motors

Continuing growth in electric motor size is coupled with greater need for reliable interconnection between motor and power system to minimize process downtime. Yet the many standards governing electrical clearance, moisture resistance, grounding, safety, and cooling of electrical apparatus have little to say about that interconnection located within the motor terminal box. The traditional bolted and taped terminal lug joints, requiring long hours of skilled labor to make up, need remaking each time the circuit must be opened for testing or motor servicing. The high-voltage separable connector, forming a watertight, yet easily removable joint at low cost, now offers a suitable alternative if its limitations are fully understood.

New data sheet on high-voltage connectors

Three–dimensional (3D) ground–penetrating radar (GPR) represents an efficient high–resolution geophysical surveying method allowing to explore archaeological sites in a non–destructive manner. To effectively analyze large 3D GPR data sets, their combination with modern visualization techniques (e.g., 3D isoamplitude displays) has been acknowledged to facilitate interpretation beyond classical time–slice analysis. In this study, we focus on the application of data attributes (namely energy, coherency, and similarity), originally developed for petroleum reservoir related problems addressed by reflection seismology, to emphasize temporal and spatial variations within GPR data cubes. Based on two case studies, we illustrate the potential of such attribute based analyses towards a more comprehensive 3D GPR data interpretation.The main goal of both case studies was to localize and potentially characterize tombs inside medieval chapels situated in the state of Brandenburg, Germany. By comparing the calculated data attributes to the conventionally processed data cubes, we demonstrate the superior interpretability of the coherency and the similarity attribute for target identification and characterization.

Transformer Corona Measurement Using Condenser Bushing Tap and Resonant Measuring Circuits

Analysis of resonant measuring circuits is given for measurement of corona in transformers, using a bushing capacitor tap connection and a narrow frequency band corona meter. The use of the bushing tap connection and an induced test voltage simplify the test setup. They eliminate the need for corona-free high-voltage connections and for the high-voltage coupling capacitor. Furthermore, in most cases it permits corona testing without the facilities of a shielded room. The use of the resonant measuring circuit greatly improves the sensitivity of corona measurement when the bushing tap connection is used. The circuit may be readily calibrated to render the same numerical values of corona microvolts as the standard National Electrical Manufacturing Association test, yet with a greatly simplified test setup.

Epoxy Resin-Orlon Cable Terminations for 4-Kv Service

Design of a termination for 4-kv operation on PILC cable has been described. It is based on a hand applied insulation and weather seal of epoxy-resin-impregnated orlon tape which covers the cable end from the lead sheath to the high-voltage connector. Filler materials may be added to the basic resin. Savings have been effected through the elimination of the porcelain pothead or, alternatively, through the use of paperinsulated cable throughout rather than a length of rubber-insulated cable joined to the paper-insulated cable for the terminal section. The termination successfully passed the AIEE pothead design tests, and tests described herein have further shown the adequacy of the bond between the epoxy resin-orlon wrappings and copper and lead. Previous tests1 have demonstrated the resistance of the epoxy resin-orlon wrapping to moisture penetration. Service installations have already successfully withstood the extremes of summer and winter weather. Accelerated outdoor aging tests are in progress to provide additional data on the weathering ability of the terminations. The epoxy resin-orlon termination is now standard for use on PILC cable indoors in the Baltimore Gas and Electric Company's 4-kv system and is used at selected locations out of doors.

Epoxy Resin-Orlon Cable Terminations for 33-Kv Service

Design of a termination for 33-kv operation has been described. This includes a wrapping of insulation comprising orlon tape impregnated with an epoxy resin formulation that extends over a portion of the metallic cable sheath, the oiled-paper, insulation, and a portion of the high-voltage connector. The prepared cable end is installed in a porcelain pothead which is almost completely filled with cable oil. Passage of oil between the pothead and the cable is prevented by the resin insulation. Savings are effected over standard oilfilled pothead construction in that oil reservoirs are not required, nor is periodic inspection and maintenance of oil level. Previous semisolid filled terminations required construction and filling in the shop. Additional splices were then required in the field to connect the pothead to the cable. The present termination is made in the field making additional splicing unnecessary. Temperature-cycled overvoltage tests and impulse voltage tests support the expectation of long life and adequate impulse strength level. Other test results including breakdown voltage strength, dissipation factor, dielectric constant, resistance to moisture, and adherence to metals indicate that satisfactory performance may be expected. The use of epoxy-resin-impregnated orlon terminations is now standard practice in the Baltimore Gas and Electric Company's 33-kv transmission and distribution system. More than 70 of these terminations have been placed in service since June 1958.

High-voltage ignitron rectifiers

THE DEVELOPMENT of new types of sealed ignitron tubes has made possible rectifier equipment which is capable of delivering high power at moderately high direct voltages. The lack of moving parts, long tube life, and practically unlimited emission of the pool cathode are advantages which provide a high degree of reliability. These factors bring to the high-voltage field the same high efficiency and high grade of performance which is characteristic of the low-voltage industrial rectifier equipments. A 2,500-kw unit and a 7,500-kw unit represent typical designs of 17,000-volt rectifiers. The former employs a 50-ampere sealed ignitron tube and the latter employs a 150-ampere tube. The 6-phase double-way power circuit is employed in both units because it provides better utilization of transformer capacity than other rectifier circuits. The double-way connection requires only three secondary windings on the rectifier transformer and only three high-voltage connections between the transformer and the tubes, thus requiring less insulating material on the a-c side than other power circuits.

High-Voltage Ignitron Rectifiers

THE DEVELOPMENT of new types of sealed ignitron tubes has made possible rectifier equipment which is capable of delivering high power at moderately high direct voltages. The lack of moving parts, long tube life, and practically unlimited emission of the pool cathode are advantages which provide a high degree of reliability. These factors bring to the high-voltage field the same high efficiency and high grade of performance which is characteristic of the low-voltage industrial rectifier equipments. A 2,500-kw unit and a 7,500-kw unit represent typical designs of 17,000-volt rectifiers. The former employs a 50-ampere sealed ignitron tube and the latter employs a 150-ampere tube. The 6-phase double-way power circuit is employed in both units because it provides better utilization of transformer capacity than other rectifier circuits. The double-way connection requires only three secondary windings on the rectifier transformer and only three high-voltage connections between the transformer and the tubes, thus requiring less insulating material on the a-c side than other power circuits.