US2124601A - Railway switch controlling apparatus - Google Patents

Description

July 26,1938. N. F. AGNEW ET AL RAILWAY SWITCH CONTROLLING APPARATUS Filed Match 26, 1937 2 Sheets-Sheet l ew and R nm M m lwwl d m mwym July 26, 1938.

N. F. AGNEW ET AL.

RAILWAY SWITCH CONTROLLING APPARATUS Filed Marph 26, 1957 2 Sheets-Shee'h 2 OR 57 52 6 C i fv'v vvvv v J- k 50 279 28 I .55 if 54 55 25 3 :f 12 26 I/ g 22 5 INVENTOR THEIR ATTORNEY Patented July 26, 1938 UNlTED STATES ZAZifitl PATENT QFFHQE RAILWAY SWITCH CONTROLLING APPARATUS vania Application March 26,

10 Claims.

Our invention relates to railway switch controlling apparatus, and particularly to apparatus for the protection of a railway switch motor against overload.

We shall describe three forms of apparatus embodying our invention, and shall then point out the novel features thereof in claims.

The apparatus of this invention is an improvement over that disclosed in application Serial No. 179,704 of Claude M. Hines and Bernard E. OHagan, filed December 14, 1937, for Railway trafiic controlling apparatus.

In the accompanying drawings, Fig. 1 is a diagrammatic view illustrating one form of apparatus embodying our invention. Figs. 2 and 3 are diagrammatic views each illustrating a modification of a portion of the apparatus shown in Fig. l and each also embodying our invention.

Similar reference characters refer to similar parts in each of the three views.

Referring first to Fig. 1, the reference character W designates a railway switch which is operated by the well-known dual selector type of mechanism. In the form here shown diagrammatically, this mechanism includes a dual selector lever S which operates a link 3. When the lever S is in its normal position, as shown in the drawings, link 3 connects switch W with a motor M and when lever S is in its reverse position, link 3 disconnects the switch W from motor M and connects the switch with a hand throw lever H. The selector lever S also controls a contact 4 in accordance with the position of the lever. That is, contact 4 is closed only when the selector lever S occupies its normal position. Contact 4 is included in the motor operating circuits so that energy cannot be supplied to the motor when selector lever S is moved to its reverse position to condition the switch for manual operation.

The motor M is controlled by a polarized switch control relay WR in the usual and Wellknown manner. That is, motor M is energized in one direction or the other to cause switch W to move to a corresponding position in accordance with the direction of energization of relay WR.

The polarized switch control relay WR is controlled by a lever L and an overload device OR. That is, when the overload device is in its initial deenergized condition, relay WR can be energized in one direction or the other tocorrespond to the position of lever L.

The overload device OR is here shown as a relay having two windings. As will be explained 1937, Serial No. 133,218

more in detail hereinafter, one winding 5, which we shall term an overload winding, is controlled by the current in motor M and the other winding 6, which we shall term the holding winding, is controlled by the lever L. Winding 5 is connected in multiple with a thermal resistor l which under normal conditions carries the major portion of the motor current. When the switch is obstructed, motor M draws increased current which heats up resistor to increase its resistance. This increased resistance causes a larger voltage drop across winding 5, thus Causing sufficient current to flow in winding 5 to operate pverload relay OR.

The operation of the apparatus shown in Fig. 1 will best be understood by explaining the operation and tracing the circuits simultaneously.

We shall first assume that with all parts in their normal condition, as shown in the drawings, the operator desires to cause switch W to move to its reverse position. He may do this by moving lever L to its reverse position. When lever L occupies its reverse position, relay WR will become energized in the reverse direction by a circuit which passes over a path from terminal B of any suitable source of energy through contact 89 of lever L, wire Iii, winding of relay WR, back point of contact H of overload relay OR, wire l2, and contact l3l l of lever L to terminal C of the same source of energy. When polarized switch control relay WR is energized in the reverse direction, its polar contacts 15 and. I6 will move to the right to close contacts 15-17 and I6l8.' The closing of these contacts will establish a circuit to operate motor M in the reverse direction which circuit passes over a path from terminal B through reverse polar contact l5l'l of relay WR, front neutral contact B9 of relay WR, resistor 1 and overload winding 5 of relay OR in multiple, armature i of motor M, reverse polar contact l6l8 of relay WR, reverse motor cut-out contact 2i field winding 2 of motor M, and contact a of selector lever S to terminal C. When motor M completes the movement of switch W to its reverse position, motor cut-out contact 28 will become open so that energy will be disconnected from the motor M.

We shall next assume that the switch W became obstructed and failed to reach its reverse position. In this event the current drawn by the motor through resistor 1 will cause the voltage drop across winding 5 of overload relay OR to increase to such a value that relay OR will be caused to assume its picked up condition. It

will be noted that the holding winding 6 of relay OR is connected in a shunt path which includes back contact 2| of relay OR. Holding winding 6 is connected in this shunt path so that the current induced in winding 6 by the energization of overload winding 5 will oppose the building up of flux due tothe increasing current in overload winding 5 resulting in overload relay OR having a slow acting characteristic. In other words, the shunting of the holding winding 6 causes relay OR to be slow in picking up so that momentary surges of current in the motor such, for example, as occur when the motor is starting will not cause the operation of the overload relay.

When the overload relay attains its operated or picked up condition, it Will be retained in such condition by virtue of a stick circuit which passes over a path from terminal B through contact 8-9 of lever L, wire ll], winding 6 of overload relay OR, front point of contact I! of relay OR, wire I2, and contact l3|4 to terminal C. Holding winding 6 is so connected in this stick circuit that it will be energized in a direction to correspond to the direction of energization of overload winding 5. Therefore, when lever L is 00- cupying its reverse position to operate the switch to a corresponding position, holding winding 6 will also be energized in the reverse direction. The front and back points of contact ll of relay OR are so adjusted that the front point will become closed before the back point becomes opened. The relay WR will not, therefore, become deenergized to disconnect energy from overload winding 5 before holding winding 6 becomes energized.

When the operator desires again to assume control of the switch W, he may do this by manipulating lever L to its normal position which will momentarily energize holding winding 6 in the normal direction over its previously traced stick circuit so that the flux in winding 6 will be opposed and neutralized to cause relay OR to return to its initial deenergized condition.

The operation of the apparatus shown in Fig. l to cause switch W to return to its normal position will be similar to the operation just described to move switch W to its reverse position and it is believed, therefore, that further detailed description of the apparatus shown in this figure is unnecessary.

Referring next to Fig. 2, the reference characters NWR and RWR designate a normal switch control relay and a reverse switch control relay, respectively, which relays control the motor M in a manner somewhat similar to that described for the polarized relay WR. That is, when re- I lay NWR is energized .and relay RWR is deenergized, the motor M' is caused to operate switch W to its normal position and when relay RWR is energized and relay NWR is deenergized, motor M is caused to operate switch W to its reverse position.

Relay NWR is provided with a control circuit which passes from terminal B through contact 2526 of lever L, wire 21, relay NWR, normal switch cut-out contact 22, back contact 28 of overload relay OR, wire 29, and contact 30-3! of lever L to terminal C. Reverse switch control relay RWR is provided with a circuit which passes from terminal B throughcontact 36-32 of lever L, wire 29, back contact 23 of overload relay OR, reverse switch cut-out contact 20, relay RWR, wire 33, and. contacts 3435 of lever L to terminal C.

The shunt path connected around holding Winding 6 of relay OR includes back contacts 28 and 36 of relay OR connected in series. A resistor 31 which is shunted by a branch path including back contact 36 of relay OR is connected in series with winding 6. When overload relay OR becomes picked up by an increase in the drop in potential across resistor 1 due to excessive motor current, the opening of back contacts 28 and 36 of relay OR will cause resistor 31 and winding 6 to become effective for limiting the current in the circuit for the normal switch control relay NWR or the reverse switch control relay RWR depending'upon which relay is energized. The value of the resistance of resistor 31 and winding 6 is chosen so that the current will be sufficient to maintain relay OR in its picked up condition but will not be sufiicient to maintain the relays NWR and RWR in their picked up condition. Consequently, the picking up of the overload relay OR will cause the switch control relays RWR or NWR to become released to disconnect energy from the motor M and the relay OR will be maintained in its picked up condition until such time as lever L is again manipulated. It will be noted that holding winding 6 will be energized in one direction or the other depending upon the position of lever L and that, consequently, the release of relay OR is assured when the lever L is moved to a different position due to the current reversal through winding 6.

Referring next to Fig. 3, normal switch control relay NWR is provided with a circuit which passes over a path from terminal B through lever contact 40-4I, wire 42, normal switch outout contact 22, relay NWR, back point of contact 43 of relay OR, wire 44, and contact 4546 of lever L to terminal C. Reverse switch control relay RWR is provided with a circuit which passes over a path from terminal B through lever contact 4148, wire 49, back point of contact 50 of relay OR, relay RW'R, reverse switch cutout contact 20, wire 5!, and contact 5253 of lever L to terminal C. It will be apparent that when overload relay OR is operated, the opening of back points of contacts 43 and 56 of relay OR will cause relay NWR or relay RWR, as the case may be, to become released to disconnect energy from motor M. The usual shunt path connected around holding winding 6 of overload relay OR includes the back point of contact 54 of relay OR. Two stick circuits are provided for holding winding 6 to maintain relay OR in its picked up condition. One stick circuit for energizing the winding 6 in the normal direction passes from terminal B through contact 46-4l of lever L, wire 42, front point of contact 54 of relay OR, holding winding 6 of relay OR, front point of contact 43 of relay OR, wire 44, and contact 4546 of lever L to terminal C. The other stick circuit'for energizing winding 6 in the reverse direction passes from terminal B through lever contact 41-48, wire 49, front point of contact 56 of relay OR, holding winding 6 of relay OR, front contact 55 of relay OR, wire 5|, and contact 5253 of lever L to terminal C. It will be seen,,therefore, that when overload relay OR is picked up, its holding winding 6 will be energized in one direction or the other to maintain relay OR in its picked up condition until a new operation of lever L. The front points of contacts 55, 54, 56, and 43 of relay OR are adjusted to become closed before the back points of contacts 43 and 50 of relay OR become open so that winding 6 will be energized before relays NWR and RWR become released to disconnect energy from motor M and overload winding 5.

From the foregoing description of the apparatus embodying our invention it will be seen that we have provided a simple and reliable means for controlling an overload relay for disconnecting a railway switch motor upon excessive current flow therein which relay has a slow acting characteristic so as to be substantially immune to monetary surges of current in the motor. Furthermore, we have also provided means for retaining the overload relay in its operated condition wherein the motor is rendered inoperative until such time as a new manipulation of the switch control lever is initiated.

Although we have herein shown and described only three forms of apparatus embodying our invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of our invention.

Having thus described our invention, what we claim is:

1. In combination, a motor, a control relay, means effective when said control relay is picked up to energize said motor, an overload relay, an overload winding of said overload relay connected in series with said motor to pick up the overload relay upon excessive current flow in the motor, an auxiliary winding of said overload relay, means including a back contact of said overload relay for shunting said auxiliary winding, and a circuit for said control relay including said auxiliary winding, the resistance of said auxiliary winding being such that when said back contact is opened the current in the circuit will be limited to a value which is above the release value of said overload relay but which is below the release value of said control relay.

2. In combination, a motor, a control relay, means effective when said control relay is picked up to energize said motor, an overload relay, an overload winding of said overload relay connected in series with said motor to pick up the overload relay upon excessive current flow in the motor, an auxiliary winding of said overload relay, means including a back contact of said overload relay for shunting said auxiliary winding, a circuit for said control relay including said auxiliary winding, and a resistor also included in said circuit and shunted by a back contact of said overload relay, said resistor being efiective when said back contact is opened to limit the current in the circuit to a value which is above the release value of said overload relay but below the release value of said control relay.

3. In combination, a motor, a control relay, means eiTective when said control relay is energized to supply energy to said motor, an overload relay, an overload winding of said relay connected in series with said motor to operate the overload relay upon excessive current flow in the motor, a circuit for energizing said control relay, and means efi'ective when said overload relay is operated to include in said circuit a holding winding of said overload relay, said holding Winding being eifective to maintain said overload relay in its operated condition and to reduce the current in said circuit to a value below the release value of said control relay.

4. In combination, a motor, a normal control relay and a reverse control relay, means for supplying energy to said motor in one direction or the other according as said normal control relay or said reverse control relay respectively is energized, an overload relay having an overload winding connected in series with said motor to pick up the overload relay upon excessive current flow in the motor, means including a pair of conductors and a back contact of said overload relay for energizing said normal control relay, means including another pair of conductors and another back'contact of said overload relay for energizing said reverse control relay, a holding winding of said overload relay, means including said one pair of conductors and a front contact of said overload relay for energizing said holding winding, and means including said other pair of conductors and another front contact of said overload relay for also energizing said holding winding.

5. In combination, a motor, a normal control relay and a reverse control relay, means for supplying energy to said motor in one direction or the other according as said normal control relay or said reverse control relay respectively is energized, an overload relay having an overload winding connected in series with said motor to pick up the overload relay upon excessive current flow in the motor, means including a pair of conductors and a back contact of said overload relay for energizing said normal control relay, means including another pair of conductors and another back contact of said overload relay for energizing said reverse control relay, a holding winding of said overload relay, means including said one pair of conductors and a front contact of said overload relay for energizing said holding winding, means including said other pair of conductors and another front contact of said overload relay for also energizing said holding winding, and means including another back contact of said overload relay for shunting said holding winding to retard the pick up of the overload relay.

6. In combination, a circuit, means for supplying energy to said circuit, a relay effective when operated to prevent the supply of energy to said circuit, an overload winding of said relay included in said circuit to operate the relay if the current in the circuit exceeds a predetermined value, a holding winding of said relay, means for shunting said holding winding when the relay is in its initial condition to retard the operation of said relay, and means for energizing said holding winding when said relay is in its operated condition to maintain the relay in such condition.

7. In combination, a circuit, means for supplying energy to said circuit, a normally released relay eifective when picked up to prevent the supply of energy to said circuit, an overload winding of said relay included in said circuit to pick up the relay upon excessive current flow in the circuit, a holding winding of said relay, means including a back contact of said relay for shunting said holding winding to cause said relay to be slow in picking up, and means including a front contact of said relay for energizing said holding winding to maintain the relay in its picked up condition.

8. In combination, a circuit including a resistor, means for supplying energy to said circuit, a relay efiective when operated to prevent the supply of energy to said circuit, an overload winding of said relay connected across said resistor to operate the relay if the difference of potential across said resistor exceeds a predetermined value, a holding winding of said relay, means for shunting said holding winding when said relay is in its initial condition to provide the relay with a slow pick-up characteristic, and means for energizing said holding winding when said relay is in its operated condition to maintain the relay in such condition.

9. In combination, a control circuit, means for selectively energizing said control circuit in one direction or the other, a motor including operating circuits, means for supplying energy to said operating circuits in one direction or the other to correspond to the direction of energize,- tion of said control circuits, a normally released relay effective when picked up to prevent the supply of energy to said operating circuits, an overload Winding of said relay included in said operating circuits to pick up the relay upon excessive current flow in the operating circuits, a holding winding of said relay, means eflective when said relay is released to shunt said holding winding to provide the relay with a slow pickup characteristic, and means effective when said relay is picked up to supply'said holding winding with energy in one direction or the other to corcontrol circuit.

10. In combination, a pair of conductors, means for reversibly supplying energy to said pair of conductors at one end, a motor including operating circuits, means at the other end of said conductors governed by the direction of energy in the conductors for reversibly supplying energy to said operating circuits, a normally released relay efiective when picked up to prevent the supply of energy to said operating circuits, an overload winding of said relay included in said operating circuits to pick up the relay upon excessive current flow in the operating circuits, a holding winding of said relay, means for shunting said holding winding When said relay is released to cause the relay to be slow in picking up, and means efiective when said relay is picked up to connect said holding winding to said pair of'conductors.

" NORMAN F. 'AGNEW.

CLAUDE M. HINES.

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