GB349012A - Improvements in or relating to electric ship propulsion - Google Patents

Abstract

349,012. Dynamos and motors combined for transmitting power. ENGLISH ELECTRIC CO., Ltd., 28, Kingsway, London, WILSON, J. C. and CARNEGIE, H. S., Siemens Works, Stafford. Jan. 15, 1930, No. 1430. [Class 38 (iv).] Ships having two or more propelling means and provided with means for varying the relative speeds of the propelling means have the generator and motors driving the propellers excited from a separate source and are arranged so that the variation of the relative speeds is effected by field control of one motor, or set of motors, at a time, the regulating means for the remaining motor or set of motors being inoperative while the generator field is varied proportionally but not reversed. As shown in Fig. 1 the propeller-driving motors B, C have their armatures connected in series with the generator armature A. The fields of the three machines are excited from an exciter D. Control of the motors simultaneously is effected by means of the potentiometer 2 across which is connected the generator field 1. The fields 3, 4 of the motors C, B are connected to potentiometers f, g across the terminals of the exciter D. A rheostatic regulator H in the generator field circuit has a contact 25 mechanically coupled to contacts 21, 22 and 23, 24 associated with the potentiometers f, g respectively. The fields 3, 4 are brought out to contacts 11 .. 18. Considering the action of the regulator f; at the position shown in Fig. 1 both motor fields are connected across the full exciter voltage. Upward movement of the contacts 21, 22 reduces the motor field until the position q is reached when the motor field 3 is unexcited. At the same time the contact 25 on the generator regulator H has moved upward to insert resistance 9 in the generator field circuit. Further upward movement of the contacts 21, 22 results in the reversal of the motor C with increasing field until the position r is reached when the motor C is on reversed full speed, and the resistance 9 in the generator field is all out. The contacts 23, 24 at the same time have moved upward to positions q<1>, r<1> but as the end contact 8 on the potentiometer g is connected to a strip 8a no change has been effected in the speed of the motor B. Similarly the speed of the motor B may be reduced and reversed with a corresponding variation of the generator field while motor C remains on full speed. Fig. 2 shows an arrangement whereby the rheostatic regulator 4 in Fig. 1 is dispensed with and resistances 29 .. 32 connected as shown. Variation of the voltage across the exciter fields 3 or 4 by the method described above thus results in a variation of resistance in series with resistance 29 or 31 with a corresponding variation in the drop across the resistances 30 or 32 and a consequent variation of the generator field. In the case of two or more generators the fields, regulators and limiting resistances are connected in parallel and the armatures in series.