J. K. Dillard

Influence of A-C reactance on voltage regulation of 6-phase rectifiers

INVESTIGATIONS made during the past few years have shown that methods normally used for the calculation of rectifier voltage regulation have definite limitations not generally appreciated by application engineers. It has been established that conventional methods of calculating regulation are valid only if the angle of overlap is less than 300 degrees divided by the number of phases. With larger overlap angles any a-c reactance common to two or more simple rectifiers introduces a delay angle, even though the rectifiers are operated without intentional delay. This inherent delay reduces the direct voltage and therefore increases the voltage regulation. In special applications involving large overlap angles, these limitations are of primary importance, because considerable error is possible if they are not recognized.

Voltage regulation of 12-phase double-way rectifiers

CONVENTIONAL METHODS of calculating rectifier voltage regulation are valid only if the angle of overlap is less than 360 degrees divided by the number of phases. At larger angles of overlap an inherent delay angle, introduced by a-c reactance common to two or more simple rectifiers, reduces the direct voltage and thereby increases the voltage regulation. This phenomenon has been described in two papers,1, 2 recently presented to the Institute, in which curves and equations for determining voltage regulation of 6-phase rectifiers were given. Two earlier articles5, 4 recognized the phenomenon in 6-phase circuits.

The impact of pooling on power system planning

The impact of pooling on power system planning is manifold. Pooling means a move to bigger units, nuclear plants, mine-mouth generation, and 500-kv transmission grids. The business relations between utilities and manufacturers are changing, and new areas for joint activity are opening up for them in system planning and EHV design

Field tests on a 100-megawatt rectifier installation

THE 100-megawatt rectifier station at the Robert P. Patterson Plant of the Reynolds Metals Company is the largest concentration of d-c power on a single bus in this country. Power for the plant is obtained from 24 double-Y ignitron rectifier assemblies, each rated at 5,208 amperes and 800 volts. In March 1954, an extensive field-test program, involving both load switching and arc backs, was conducted at this rectifier station.

Lightning protection of turbine generators

At present, it is the general practice to apply lightning protective equipment at the terminals of large unit-connected generators. There is a hesitation on the part of industry to omit protective equipment, even though analysis of the problem indicates that no protection is needed. This is primarily because the cost of the added insurance or protective devices is trivial when compared with the investment in a large machine, the expense of damage to the machine, and the expense of the loss of a large unit of generating capacity.

Lightning protection in extra-high-voltage stations

This analogue computer study was made of a 330-kv substation to learn whether a lightning arrester had to be applied to each transformer or whether one arrester would protect the pair of transformers supplied by each bay.

Reactance influence on 6-phase rectifiers

CONVENTIONAL METHODS OF calculating rectifier voltage regulation are valid only if the angle of overlap is less than 360 degrees divided by the number of phases. With larger overlap angles, any a-c reactance common to two or more simple rectifiers introduces an angle of inherent delay, even though the rectifiers are operated without phase control. This inherent delay reduces the direct voltage and, therefore, increases the voltage regulation.

A study of lightning protection in extra-high-voltage stations

Results of this study reveal that variations in magnitude and wave shape of voltages caused by lightning surges in extra-high-voltage stations are great enough to be of economic importance in the selection of insulation levels of station equipment.