The inductances of a D.C. machine under transient conditions.
|Title:||The inductances of a D.C. machine under transient conditions.|
|Abstract:||The behaviour of inductance, self and mutual, is of considerable interest, especially in the case of d.c. machines operating in power and control systems, where the accurate prediction of the behaviour is of importance under both transient and steady-state conditions. Existing methods of measuring the inductances of the coils of a compound-wound d.c. machine with interpoles are compared with a view to recommending simple methods that will be suitable for all the coils from the highly-inductive shunt-field to the comparatively non-inductive armature. The thesis discusses the distinction between the transient, incremental and apparent inductances and surveys appropriate methods of measuring them. The experimental work considers and eliminates, in turn, the effects of the carbon brushes by making measurements with them in the circuit and then with direct connections to the commutator of a 5 KW machine. In all the inductance measurements the effects of direct-axis saturation and hysteresis are considered. Hay's bridge is considered to be the most convenient single method suitable for measuring all the machine self-inductances. The bridge is operated over a frequency range of 1. 66 c/s to 60 c/s to observe the effect of eddy currents in the solid iron driving flux into leakage paths at the higher frequencies. Mutual inductances are measured by a simple ammeter-voltmeter method and the variations with rotor angle of mutual inductances between the stator and direct-axis coils and the armature coil, are investigated for the purposes of commutation analysis. The polar moment of inertia of the rotor is determined by both mechanical and electro-mechanical tests. Theoretical transient curves are predicted for the machine operating both as a generator and as a motor and the curves are compared with those from actual tests. Due to the unpredictable nature of hysteresis and brush-contact effects when the machine is in normal operation, the distinction between transient, incremental and apparent inductance is found to be practically unimportant for this machine.|
|Collection||Thèses, 1910 - 2010 // Theses, 1910 - 2010|