US1656321A - Protection of lamp controllers - Google Patents

Description

Jan. 17, 1928;

. 1,656,321 E. DICK PROTECTION OF LAMP CONTROLLERS 2 Sheets-Sheet 1 Filed May 5. 1924 All AlAAAll IIII II" M@LJV Jan, 17, 192s.

E. DICK.

PROTECTION OF LAMP CONTROLLERS Filed May 5. 1924 2 Sheets-Shee't 2 Patented Jan. 17, 1928.

PATENT OFFICE.

EMIL DICK, OF GENEVA, SWITZERLAND.

PROTECTION OF LAMP CONTROLLERS.

Application filed May 5, 1924, Serial No. 711,021, and in Germany May 7, 1923.

There are frequently employed, in connection with train-lighting systems in which dynamos and storage-batteries are used, lampcontrollers that efiect, in the network or circuit of the lamps, the maintenance of the most constant potential practicable. Essentially, the lamp-controller comprises an electromagnet which is influenced by the lamp-potential and the regulating member ofwhich suitably adjusts the quantity of the regulating resistance that is interposed in the lamp-mains. In this way, there is wiped out or neutralized the difference between the load-potential of the dynamo and the mean discharge-potential of the storage-battery in the lamp-resistance through which the current flows. If, in the case of apparatus heretofore known, there should appear, in the network of the lamps, an excess of current, which might, for example, arise from a short circuit, this excessive current due to the short circuit would flow through the lamp-controller and so would burn out the lamp-resistance and its contacts, as a result. This invention has for an object to protect the lamp-controller against the destructive effects of excessive currents. In the drawings illustrating the principle of this invention and the best mode now known to me of applying that principle, Fig. 1 is a diagrammatic (or schematic) view of an apparatus adapted and designed to protect a lamp-controller from an overload current; and Fig. 2 is a similar view showing a modified form of such an apparatus.-

The dynamo A is provided with an arma ture 1 and field-windings 2 and is controlled by an automatic regulator B having 'a regulating resistance 3 and a contact 1 that is actuated by the solenoid 5, which is shown in a shunt circuit but which may, however, be energized by series current. For the adjustment of the controlled potential of the dynamo A, there is provided the achustmg resistance 6. There is depicted likewise only diagrammatically the automatic circuitbreaker 7, which connects and disconnects the dynamo A to and from the storage-battery 8 (or, in effect, the network or bank'C of lamps 14), in case an equalization of elec trical potential is to be or (as the case may be) is brought about. The lamp-controller D shown in Fig. 1 includes a regulating resistance 9 which is interposed in one of the mains of the lamp-circuit and the regulating contact 10 of which is shifted automatically by the solenoid 11 in a manner dependent upon the variations in the potential at the lamps let; while the lamp-controller D shown in Fig. 2 comprises five regulating resistances 9*. In series with the winding 1 the solenoid 11 there isincluded an adjust ing resistance 12 which is about four times as great as the resistance of the winding of the solenoid 11, and the purpose of which is to compensate for the effect produced by the heating of the latter. 13 denotes the main lamp-switch, by means of which the bank C of lamps let may, as need arises, be thrown into and out of circuit. 15 denotes fuses in the lamp-circuit.

For the protection of the lamp-controller D from a current overload, there is provided a relay E, which comprises an electromagnet on the core E of which are mounted the shunt-winding 16 and the series-winding 17. The shunt-winding 16 shown in Fig. 1 is subdivided and the terminals of the sections are suitably connected with the lamp-regulating resistance 9 by the connecting- wires 16, 16"; while the shunt-winding 16 illustrated in Fig. 2 is not subdivided. To a lever 20 there are fastened the armature 18 ot the relay E and the yielding contacts 19,

away from the stationary contacts 22, 23,

against the magnetic pull of the electromagnct E, no excess current then flowing through the lamp-regulating resistance 9. In case of a short circuit in the lamp-network (for example), there will flow a current of excessive intensity from the two sources of current (the dynamo A and the storage-battery S, or from only the latter, as the case may be, if the dynamo A is cut out of circuit), through the lamp-regulating resistance 9 to the place where theshort circuit exists; and, in this event, there appears, in the lamp-regulating resistance 9, a poten tial drop that is determined by the intensity of the current due to the. short circuit and the ohmic resistance of the lamp-regulating resistance 9 and which may be several times as great as the potential drop therein present under normal working conditions. An inspection of Fig. 1 will show that, as the contact 10 is pulled up by the solenoid 11 and is thereby shifted along the lamp-regulating resistance or rheostat 9, the coils of the shunt-winding 16 are energized one after another, the lowermost coil, being first'energized, then the lowermost coil and the middle coil together, and, finally, all three coils. By making a suitable selection of the number of turns and the resistances of the coils of the shunt-winding 16 and by taking a suiiicient'number of such'coils and properly choosing the points on the lamp-regulating resistance 9 for the connection of wires leading thereto from those coils of the shuntwinding 16, it becomes practicable to arrange for the actuation of'the relay E due to a short circuit or to an overload in the network C of lamps 14. .In case of an excessive current arising from a short circuit or from an overload in the lamp-circuit C, the relay E operates in such manner that the greater the momentary or instantaneous resistance of the lamp-regulating resistance 9 is, the smaller is the excess current required to actuate the lever 20 so as to bring the contacts 19, 22, 23, together; and, at the instant of this contact-making, the lamp-regulating resistance 9 and the shunt-winding 16' become short-circuited and the excessive current flows thereupon through the serieswindingl'? of the electromagnet E from which it results that the latter continues energized and the contacts 19, 22, 23, remain closed so long as the flow of excessive current continues or persists. In this attracted position of the relay-lever 20, the excessive-current'is shunted aroundthe regulating resistance 9 so that almost none of the latter current flows therethrough. The shunt path of the excessive current is, naturally, the path of least resistance; and it may be traced asfollows: 1 to 7 to 20 to 19 to 22 to 17 to 13 to 15 and thence tothe place where the short circuit-exists in the lampcircuit, and, from there, back to the other pole of the dynamo 1. Owing to the high resistance of the solenoid 11 as compared with that of the path of thecurrent through the place where the short circuit exists in the lamp-circuit, almost none of the excessive current flows through the coil 11. In this condition of the apparatus, in which the contacts 19, 22, 23, are closed, the solenoid 11 is therefore made inoperative (or deener- 'gized)", to the end that the regulating-contact 10 is restored by gravity to its initial lowermost position as rapidlyas practicable, in which position the lamp-regulating resistance u 9 is short-circuited. After the eradication of the short-circuit has been effected (as, for example, by the melting of one of the fuses 15), there vanishes also the excessive current, and simultaneously the lever 20 is jerked back to itsrest-position andrcarries with it thearmature 18 of the relay E, whereby the electrical contact existing between the parts 19,22, 23, is destroyed or interrupted.

In Fig. 1, the lamp-regulating resistance or rheostat 9 is illustrated as a series-resistance, the'individual resistances of which are thrownv into c1rcu1t one after another. Nevertheless, under certain circumstances,

the parallel arrangement of the individual resistances of this rheostat is found more suitable for certain makesof lamp-controller. In Fig. 2, there is illustrated a lampcontroller D that comprises individual resistances 9 arranged'in' parallel. Each of the five lndivldual resistances 9 is connected, 1

on the one hand, to its own individual block or segment 24, and on the other hand, to a common bar 27. In addition there "is :provided a resistance 9', which diiiers,however,

from the resistances 9 in that itis not controlled. For the control of the resistances 9 there is provided a regulating member or lever 26 that is fulcrumed at the point 25 and which is actuated by the solenoid 11 and which, when so actuated, raises from the blocks 24 a certain number of the yielding contacts 10*, the number thereof raised depending upon the position assumed bythe controlling lever 26; bythis movement of the latter, the resistance required at the particular instant is introduced into the lamp-circuit C. The series-winding 17 that surrounds the core of the electromagnet E" of the relay E" forms part of the main C of the therethrough always flows through the magnet-winding 17 also. 7

lamp-circuit, "so that the current-flowing The gist or principle of this inventionre- 2 sides in that there is employed or utilized for the automatic short-circuitin'g of the lamp-regulating resistance, either the current of excessively high intensity that flows temporarily through" the lamp-regulating resistance, or the abnormally great potential drop existing at the instant in that resistance,

or both this abnormally high current-intensity and excessively great potential drop; and that, after the operation of the relay, the excessively high current is led over a short-circuit path; and that, after the shortthoroughly well understood that I intend to include .within the scope of the. claims that follow hereinafter all changes that do not depart from the spirit of this invention. For example, the winding 16 may bereplaced by one made up of series-wound and shunt-wound coils or of only series-wound coils and. these coils maybe suitably-.jconmechanism controlling the same; a relay that is brought into action by the existence of an abnormal electrical condition at the rheostat and by the acting of which said mechanism is rendered inoperative to permit said device to be returned to its initial position; and a normally-open path that is closed by the acting of the relay to permit the passage of abnormal current around the 20 rheostat.

EMIL DICK.

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