摘要:

Differential feeder protection, in general, uses a single relaying quantity derived from all phases of the system being protected. The paper contains a comprehensive analysis of the nature of this relaying quantity for the whole range of single shunt faults and all likely combinations of phase-sequence quantities extracted from the faulted system. The analysis includes the well-established case of the summation transformer, this device having an output which contains positive, negative and zero phase-sequence components of current. The analysis is presented in the form of curves giving the relaying quantity in terms of the important components of the various phase-sequence impedances of the power system. From these curves it is possible compare the different ways of deriving the single-phase relaying quantity and thence to specify the general rules for selection phase-sequence networks.In order to provide a comprehensive method for determining a differential relaying quantity in magnitude and phase, a general chart has been developed; from this, the magnitude and phase of the relaying quantity, derived from any specified phase-sequence network, may be obtained graphically in terms of the positive and zero phase-sequence reactances and the zero-sequence resistance of the power system.Finally, the effect of load current on the magnitude of a derived relaying quantity has been considered. The corresponding effect on phase has not been treated since it has already appeared elsewhere, although the results have been included for purposes of comparison and completeness.

DOI:10.1049/pi-a.1960.0012

出版商:IEE    

年代:1960

数据来源: IET

摘要:

The paper describes a new type of ‘definite’ impedance relay applicable to the protection of power transmission systems. Its operation is based upon a differential balance, under normal conditions, between the output from Hall effect in a semiconductor element and a rectifier unit. The experimental results obtained demonstrate the success of this instrument in principle and show that it has many advantages over the usual induction type of impedance relay.

DOI:10.1049/pi-a.1960.0013

出版商:IEE    

年代:1960

数据来源: IET

摘要:

The paper deals with the development of equipment for measuring the torque and load angle of an electrical machine under transient conditions and its use in verifying some theoretical results. The equipment is used in conjunction with a ‘micro-alternator’, which is a small machine specially designed to simulate a large generator.The torque meter uses resistance strain gauges mounted on a special coupling connected mechanically to the machine shaft. The load-angle meter operates by generating a succession of pulses which modulate the intensity of an oscillograph beam as it traverses a periodic wave.The experiments recorded relate to the following conditions:(a) Oscillations superimposed on steady operation as a synchronous machine.(b) Sudden short-circuit of an alternator.

DOI:10.1049/pi-a.1960.0014

出版商:IEE    

年代:1960

数据来源: IET

摘要:

The paper develops theoretical methods of calculating the variation of torque and load angle of a synchronous machine connected to a fixed supply voltage. In order to supplement and explain the results of recent full-scale tests the following conditions are considered:(a) Condition after a sudden short-circuit.(b) Condition after switching in a reactance between the generator and the supply.(c) Asynchronous operation.(d) Resynchronization after asynchronous operation.In a companion paper experimental equipment for measuring the variations of torque and load angle of a small synchronous machine is described. The equipment has been used to verify the theoretical results for each of the above conditions. The machine tested was a model alternator or ‘micro-alternator’ which simulates a typical large machine. The special laboratory equipment is of great value for studying in detail the factors governing the performance of large alternators.

DOI:10.1049/pi-a.1960.0015

出版商:IEE    

年代:1960

数据来源: IET

摘要:

The paper has a threefold object. First, to establish the precise significance of 3-phase power, reactive volt-amperes and total voltamperes, secondly to examine the suitability of these quantities as a basis for a tariff system and thirdly to analyse the possible metering circuits to determine what they actually measure and what are their errors.The accepted definitions of power, reactive volt-amperes and total volt-amperes are established for a single-phase circuit, and the relation between these and the physical conditions of energy flow is examined. The extension of these concepts to 3-phase systems reveals the somewhat arbitrary nature of the quantities which form the basis of many metering systems.Consideration is then given to what a metering system should attempt to measure and whether the integrated values of watt-hours, reactive volt-ampere-hours and total volt-ampere-hours, together with some indication of maximum demand, give adequate information for the assessment of tariff charges.The analysis of 3-phase metering circuits is made in terms of symmetrical component theory. The possible circuits are tabulated and the total measured quantity is specified as a function of the power and reactive volt-amperes of the positive-, negative- and zero-sequence components. By comparing these data with the symmetrical components actually present under any particular conditions, the suitability of the methods of measurement and their errors are readily derived.

DOI:10.1049/pi-a.1960.0016

出版商:IEE    

年代:1960

数据来源: IET

摘要:

The method of speed control most generally used at the present time relies upon the centrifugal governor which controls the power admitted to a driving machine, generally a prime mover, in relation to the difference between the speed of the machine shaft and a selected basic or no-load speed.Other methods of control are, however, possible, and one which appears to have certain advantages is that in which the power input is controlled in relation to the angular displacement between the machine shaft and another shaft which rotates at a defined and constant angular velocity. This has been called displacement governing, and an attempt is made here to investigate the performance of displacement governors when controlling the power supply to turbo-alternators working in the steady state.The performance of such governors under transient conditions has already received attention, but as far as the present authors are aware, the steady-state performance has not been explicitly treated before.

DOI:10.1049/pi-a.1960.0017

出版商:IEE    

年代:1960

数据来源: IET