The paper describes the design of a fail-safe sensor used for the detection of the speed of a moving railway vehicle. The sensor is required for use in automatically controlled trains that run at one of a number of predetermined speeds, selected with reference to safety criteria, and governed by conditions ahead of the train. The device uses an axle-coupled permanent-magnet a.c. generator that, at the predetermined speed, saturates a transformer with low-frequency current, choking the passage of an audio-frequency signal from a constant-voltage source, and hence cutting off the output. Positive feedback is employed to sharpen the cutt-off slope. A computer model based on a sinusoidal analytical method, superimposing the low and audio-frequency signals, predicts the possibility of instability and hysteresis occuring in the output characteristic under certain conditions. Computed and test results are found to be in good agreement, and a series of circuit-design criteria are derived.
Design of fail-safe electromagnetic train-speed sensor
Entwurf eines steurungssicheren elektromagnetischen Zuggeschwindigkeits-Messfuehlers
Proceedings of the IEE ; 125 , 11 ; 1239-1244
1978
6 Seiten, 14 Bilder, 7 Quellen
Aufsatz (Zeitschrift)
Englisch
MESSFUEHLER , GESCHWINDIGKEITSMESSUNG , EISENBAHN , DIGITALSIMULATION , BETRIEBSSICHERHEIT , AUTOMATISCHE ZUGSTEUERUNG , ROTOR (ELEKTRISCHE MASCHINE) , MODELLUNTERSUCHUNG , FREQUENZ , STROMKREIS , NIEDERFREQUENZ , ERSATZSCHALTBILD , NETZWERKANALYSE , RESONANZ , INSTABILITAET , RECHENVERFAHREN , TOLERANZ , AUSGANG (ELEKTRISCH) , KENNLINIE , OPTIMIERUNG , WECHSELSTROMGENERATOR
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