Abstract: An electrical machine has a stator, a rotor, and radially extending coolant passageways provided in a laminated core section of at least the stator. The coolant passageways are defined between axially spaced stacks of laminations in the laminated core section. The radial passageways are connected to coolant supply ducts through a gap between the stator and the rotor. More efficient cooling of the machine is obtained by providing a matrix of coolant duct sections extending circumferentially and axially of the core section. The matrix has first and second radially spaced apart faces respectively in fluid communication with the radially extending coolant passageways in the laminated core section and coolant exhaust ducts.

Abstract: To provide effective seals between the separator plates of fuel cells, particularly planar solid oxide fuel cells (SOFC's), a method of applying a glass-ceramic coating to such a separator plate comprises providing a laminar body incorporating a glass powder, e.g., a tape-cast sheet, forming a bond between the laminar body and the separator plate to form. an assembly comprising the separator plate and the laminar body, and heat-treating the assembly to convert the glass powder to a glass-ceramic.

Abstract: An operating mechanism for an autorecloser provides an improved form of mechanical interlock between the circuit breaker element (3) of an autorecloser and a disconnector (2) in electrical series with it A shaft (82) transmits linear motion between the circuit breaker's moveable contact and the profile of a bell crank (50), the bell crank being attached to a link (70) for manual rotation of the bell crank and also to a link (60) for moving a moveable contact (20) of the disconnector between CLOSED and OPEN positions. The geometry of the bell crank profile and linkages is such that when the bell crank is rotated clockwise through an angle X from a starting position in which the moveable contacts of both the circuit breaker and the disconnector are in the CLOSED position, the moveable contact of the circuit breaker is moved to an OPEN position while the moveable contact (20) of the disconnector is maintained CLOSED.

Abstract: Faults on power lines are detected by measuring the voltage and current at one end of a power line and using these measurements, together with values of series and shunt parameters of the line, to calculate values of voltage and current at an intermediate point on the line—the so-called “reach point”. At least the calculated voltage is used to determine whether a fault lies within a particular zone on the line. The calculation utilizes a value of a derivative of the measured current with respect to time and is able to take into account the sectioning of a line into discrete lengths corresponding to, for example, overhead and cable sections. To increase accuracy, the line or each discrete section of the line is conceptually divided into subsections each having its own parameter values.

Abstract: When directional overcurrent protection relays are included at the load end of a set of parallel feeders fed from an AC power source, a minimum fault-current threshold is specified based on the potential of a phase-to-phase fault at the source to cause a relay to operate misleadingly. This threshold is, for plain (transformerless) feeders, approximately 50% and, for transformer feeders, approximately 85% (nominally 86.7%) of rated pre-fault load current. These thresholds can, however, be ignored if the relay outputs are processed in a 2-out-of-3 circuit, so that a relay on one phase will only operate its associated circuit breaker if a relay on another phase has also operated, a condition which has been found not to obtain in the case of a source fault.

Abstract: In a method for predicting harmonic-distortion values for the application of a desired step change of capacitance to an AC system, an initial step change is applied and, from this change, a value of harmonic impedance of the system for each of a number of harmonics is determined. From these harmonic-impedance values corresponding values of damping resistance are, in turn, determined and, using the determined harmonic-impedance and damping-resistance values, corresponding values of an electrical load parameter, preferably load voltage, are determined for the desired step capacitance change. The method is conveniently extended to cover a method and apparatus for applying power-factor correction capacitance, in which the load-voltage values for the various harmonics are evaluated to see if they represent a potential resonance condition and, if so, a step change other than the desired change is applied. Where no resonance is indicated, the originally intended step change is applied.

Abstract: Power equipment, e.g. in the form of an electrical sub-station, for use underwater incorporates heat exchange equipment for dissipation of heat to the surrounding water. The equipment may utilise a casing having a hollow tubular element (50) extending therethrough or may utilise an arrangement with two chambers (111, 112) between which a fluid is circulated.