Isolated Phase Bus Research Articles

Isolated-Phase Bus Enclosure Currents

In the continuous-enclosure type isolated-phase bus, the enclosure current in amperes is very nearly equal to the conductor current. It lags the conductor current by somewhat less than 180°. The external flux is relatively small, and any induction heating in material or induced volts in instrument or control circuits adjacent to the bus will be negligible. Methods for determining the actual current in the enclosure and the external magnetic field are developed in this paper.

Isolated Phase Bus Enclosure Loss Factors

A basis is given for the formulas and charts included in the IEEE Committee Report, Guide for Calculating Losses in Isolated Phase Bus.

An Analog Method for Determining Losses in Isolated-Phase Bus Enclosures

Equations and curves are given which enable the designer to calculate the watt loss in isolated-phase bus enclosures, either of the noncontinuous or continuous type. The equations were derived from an analog method utilizing the electrolytic field analyzer. When using high-conductivity enclosures, such as aluminum or copper, the proximity effect between enclosures cannot be neglected in calculating enclosure losses.

Heat Losses in Isolated-Phase Bus Enclosures

Formulas are given for the evaluation of heat losses in the enclosures of isolated-phase bus installations in flat configuration. Middle-and outside-phase losses in open-circuited and electrically bonded enclosures are considered. Middle-phase open-circuited enclosure losses estimated by the proposed formula are compared with loss values inferred from temperature data on 40 heat runs involving a wide range of design parameters. The comparison shows acceptable agreement.

Minimizing the Magnetic Field Surrounding Isolated-Phase Bus by Electrically Continuous Enclosures

This paper describes a bus with electrically continuous phase enclosures interconnected at both ends. Currents in the shielding loop thus formed reduce external magnetic flux to less than one tenth the amount experienced with a discontinuous sheath. Circulating currents in nearby metallic loops are greatly reduced thereby, making joint insulation and banding of steel beams unnecessary. Over-all sheath losses are practically unchanged, for shielding current losses are approximately balanced by substantial elimination of sheath eddy-current losses. Analytical predictions are confirmed by tests.

Bersimis II Powerkouse Plan Arrangement-Description of Apparatus

A plant designer's view of an outdoor 850,000-hp (horsepower) hydroelectric plant in northeastern Quebec is presented. Twelve-foot spherical penstock valves have double seals. Steel scroll cases for the 171,000-hp turbines were completely assembled by welding in the field. Generators have self-lubricated bearings without oil lift for starting. Highspeed regulators provide for charging of long lines. A 6,000-amp (ampere) 15-kv isolated-phase bus is employed. Transformers step up to 300 kv. Control protection, station service, and accessory equipment are described.

High-capacity isolated-phase buses

THE ISOLATED-PHASE BUS, which has become the standard method for connecting power generators to transformers, has presented some problems on inductive heating of adjacent material, and there has been some question of the possibility of pressurizing the installed bus to exclude dust. Laboratory tests on these buses, run at 11,000 amperes and 15,000 amperes, and laboratory and field tests on cover tightness have produced valuable statistics for calculating induced heating and for checking cover tightness.

A new isolated-phase bus design

A new isolated-phase bus design

Isolated-phase bus system completed at Moses Powerdam

Isolated-phase bus system completed at Moses Powerdam

Welded Aluminum Conductors in Isolated Phase Bus

Welded Aluminum Conductors in Isolated Phase Bus

138-kv isolated-phase bus and switching structure

A DEFINITE TREND has been indicated toward higher subtransmission voltages to meet increasing load demands in certain metropolitan areas. High-voltage metal-enclosed isolated-phase bus structures offer a practical and economical solution to the bus and switching needs at these higher voltages and have many advantages such as simplification of arrangement, greater flexibility, and greater safety. Following this trend, the Consolidated Edison Company of New York installed a 138-kv metal-enclosed isolated-phase bus and switching structure at their East River plant. The bus structure provides for four 138-kv incoming circuits and six 69-kv circuits. Limited space made it necessary to mount the equipment at several levels (Fig. 1).

A New Isolated-Phase Bus Design

THE ISOLATED-PHASE BUS which is described here has been developed to meet the need of the modern generating station for a design which is simple to install, has tight enclosure joints, adequate mechanical support and insulation, and easy accessibility when required.

Cantilever-Loaded Insulators for Isolated-Phase Bus [includes discussion

Previous tests and experience have shown that the reliability of isolatedphase busses was not reduced in changing the insulator loading from compression only to compression-tension. Mathematical studies and laboratory tests of the shielding effect of the enclosure1 show that the reduction in force on the insulators is of considerable magnitude. This makes the use of the cantilever loaded insulators a very practical solution to the problem of reducing the number of insulators in the bus. Tests have shown that the isolated phase bus with cantileverloaded insulators will withstand the maximum momentary currents now available with ample factors of safety. An isolated-phase bus was tested up to 350,000 amperes, rms, with insulators spaced 8 feet apart. Even at this high value of current the load on the insulators was 26 per cent under the actual breaking load of the insulator assembly as determined by test. The load on the insulator was less than 15 per cent of the load which would have appeared if the enclosures were not present. At 200,000 amperes, the insulator was loaded to only 77 per cent of the National Electrical Manufacturers Association (NEMA) rating. This is powerful proof of the shielding effect of the isolated-phase enclosures, and that the cantilever insulator is more than adequate to meet present and future momentary requirements.

A new isolated-phase metal-enclosed bus

THE DESIGN of bus runs for high capacity generating stations always has received considerable attention in order to insure freedom from faults of any type. A metal-enclosed nonventilated isolated-phase bus has been developed which combines a high degree of reliability with immediate accessibility for inspection or maintenance. By questioning operating, construction, and consulting engineers the following specifications were established to guide the development of the new design: 1. Ultimate design is to permit shipment of complete factory-assembled sections to reduce field installation time to a minimum.