Abstract: A braking system for, primarily, separately excited D.C. traction motors, in which rheostatic braking is effected by field reversal to generate armature current freewheeling through the low impedance supply and through a brake resistor in series with the armature. A contactor shorts out the brake resistor for normal motoring. Field excitation in conjunction with armature current or armature voltage polarity reversal is detected to indicate the motor generating function, lock open the motoring contactor and prevent short circuiting of the motor/generator. Plug braking by energisation of the armature supply is thus always permissible either by brake handle and power handle or reverse handle and power handle. The armature current then contains a rheostatic braking component and a tractor braking component. What would normally be mis-use of the reversing control to achieve rapid deceleration thus becomes acceptable.

Abstract: A furnace for heating one or more bodies in which heated gas is introduced into the furnace chamber through one or more injectors and are conveyed to the bodies in a manner involving appreciable resistance to gas flow. In a preferred arrangement a continuous metal strip is conveyed through the furnace on a gaseous support cushion, the gas being introduced into the furnace under pressure through injectors which communicate with the lower portion of the furnace. The injectors generate a substantial recirculation of gas within the furnace.

Abstract: A saturated reactor of the type, for example the treble-tripler reactor, in which groups of 3-phase windings are connected in series to produce multiple flux phases in respective core limbs to achieve harmonic compensation. The windings are connected between the line terminals and a star-point which cannot normally be earthed if large 3rd harmonic components are to be avoided. In this invention the zero-sequence impedance of the reactor is kept at a low value by duplicating the complete primary winding and connecting the two duplicates in zig-zag star. The resulting star point can then be earthed without upsetting the harmonic compensation of the reactor.

Abstract: An alternating current power transmission system employing a long transmission line has a stabilizing arrangement comprising a plurality of alternating current saturated reactors connected to intermediate stations along its length, at least some of the reactors having slope correction capacitors in series therewith, and others of the reactors having slope reactances which are not connected by series slope correction capacitors. Since the uncompensated reactors have a substantially instantaneous transient response the stabilizing arrangement gives an overall voltage control which is better than one incorporating only slope corrected reactors.

Abstract: Ions are formed from an unknown substance in a first ion source of a double beam mass spectrometer and accelerated therefrom at a low accelerating voltage, e.g. 1kV or 2kV. Ions are formed from a reference substance in the second ion source and accelerated therefrom at a relatively high accelerating voltage, e.g. 8kV. The ion beams so formed pass through a common magnetic analyser to produce respective mass spectra. With pefluorokerosene as a reference substance producing a reference mass scale up to about 1000a.m.u., the mass spectrum of the unknown substance can be accurately calibrated (mass marked) up to 8000a.m.u. or 4000a.m.u. (with the above exemplary low accelerating voltages). Thus the invention enables the inherently very accurate chemical mass marking ability of a double-beam mass spectrometer to be scaled up along the mass scale of the unknown substance.