US2166061A - Interlock system - Google Patents

Description

July 11, 1939. R, L, KIRK INTERLOQK SYSTEM Filed Aug. 2, 1937 2 Sheets-Sheet 1 INVENTOR flak/I A. mw/r K.

[I -|ND|CATES BOLT EXTENDED-KEY OUT OF LOC I INDICATES BOLT WITHDRAWN KEY IN LOCK.

Patented July 11, 1939 UNITED STATES PATENT OFFICE INTERLOCK SYSTEM trustee Application August 2, 1937, Serial No. 156,889

4 Claims.

This invention relates to interlock systems in which standard locks are mechanically associated with, or related to, mechanical or electrical equipment in such a manner as to require the operation or movement of the respective parts or pieces of the equipment in a predetermined sequence to predetermined positions, consecutively, before permitting operation of or access to a major piece of apparatus controlled by, or associated with, the equipment.

In electrical systems, for example, it has been customary to interlock the disconnect switches, associated with a circuit breaker, in such a manner as to require the circuit to be opened at the circuit breaker before access could be had to the switches or their operation effected. After the circuit was so opened, the breaker was locked open and the associated disconnect switches subsequently locked open, in sequence. The breaker was then unlocked to permit testing or repair of the circuit breaker, with the assurance that the breaker could not be energized from the associated circuit while the operators were working upon the circuit breaker.

Such interlock systems involved the employment of a lock with each movable part that was to be moved to a safety position, and the locks were so related and co-ordinated that each piece of equipment in the interlocking sequence had to be locked in its safety position before a key would be released from the associated lock to operate a succeeding lock in the prearranged sequence.

General interlocking systems of such type, and

lock structures particularly suitable for such applications, are disclosed in my co-pending applications Serial No. 572,998 filed Nov. 4, 1931 now matured into Patent No. 2,065,859, dated Dec. 29, 1936, and Serial No. 692,457 filed Oct. 6, 1933.

When a circuit breaker alone must be tested or repaired, it is isolated by locking open the associated disconnect switches. Where, however, the abnormal condition that requires testing of the electric circuit is external of the breaker itself, as for example, where a section of power cable has become faulty and has had to be replaced, isolation of the breaker is not desired since it must be utilized for phasing purposes to check the proper re-connection of the conductors of the repaired cable sections.

However, in view of the prescribed normal sequence of operations imposed upon the circuit breaker and the disconnect switches by the usual interlock system for complete isolation of the breaker, additional or auxiliary locking equipment must be supplied to provide a necessary interlock key to permit the closing of the circuit breaker before the closing of both disconnect switches.

An object of this invention is to provide, in an interlock system of the type in which the keys for 5 unlocking the several devices are released upon the successive actuation of the devices in predetermined order, a master lock for controlling the actuation of one of the devices, the master lock being operable by the key which is released upon the completion of the sequential actuation of all other devices or, alternatively, by a key which is released by the actuation of a predetermined intermediate device in the sequence. An object is to provide an interlock system for use with a plu- 1'5 rality of related electrical devices, the system including for one electrical device a master lock operable by the keys which are released by the interlock elements of at least two of the other electrical devices, whereby the electrical device having the master lock may be actuated in a predetermined manner under different conditions of adjustment of the several associated electrical devices. A further object is to provide an interlock system capable of enforcing the sequential operation of some or all-of several related devices, the system being of simple design and including no elements additional to those required for obtaining the sequential operation of all of the related devices As applied to a circuit breaker system, the invention provides a simple and inexpensive interlock which may be actuated to obtain the complete isolation of the circuit breaker by locking open both disconnecting switches when work is to be done upon the circuit breaker itself. At the same time the system will be flexible to permit reclosing of the circuit breaker after looking open only one disconnecting switch, to permit test operations to be made upon the circuit and through the circuit breaker for checking proper phase con nections across the open disconnect switches.

By way of example, I have illustrated the application of my principle to a part of an electrical system, and the manner in which a standard interlocking system may be modified to embody the principle of my invention is schematically illustrated in the accompanying drawings, in which Figure 1 is a diagrammatic and schematic view illustrating a portion of an electrical circuit including a circuit breaker and the associated disconnect switches, together with the associated locks of the interlocking system, with all parts 01 the circuit in normal closed operating positions;

Figure 2 is a similar view with the breaker and the disconnect switches locked in open position and illustrates the corresponding positions of associated lockbolts;

Figure 3 illustrates a modification of the interlock arrangement according to present practice for the system in Fig. 1, in order to provide an auxiliary key to operate the circuit breaker for phasing, without requiring the complete sequence of operation of the entire interlocking system;

Figure 4 is a similar view of the circuit of Fig. 1 illustrating how the advantages and flexibility of the interlock system of Fig. 3 may be procured Without the addition of auxiliary equipment, but by making the look at the circuit breaker a master lock according to my invention;

Figure 5 is a longitudinal sectional view of a lock cylinder of the tumbler type showing the usual arrangement of six tumblers;

Figure 6 is a transverse sectional View showing the relative arrangement of one of the tumblers and the rotating barrel in the cylinder;

Figure 'l is a side sectional view of a tumbler cylinder similar to that of Fig. 5 provided with a set of tumblers similar to the corresponding tumblers of the cylinder lock in Fig. 5 in order to serve as a master lock with the lock of Fig. 5;

Fig. 8 is a side View, with parts in section, of a lever type of lock.

Figure 9 is a front elevational View of the lock in Fig. 8 and illustrates the disposition of the levers in two planes at right angles to each other;

Figure 9a is a fragmentary sectional view i1- lustrating the manner of looking a key in a key barrel.

Figure 10 is a side elevational view of the rotating barrel of a lock similar to that of Fig. 8 provided with only one group of levers having the same patterns as the corresponding levers in the lock of Fig. 8, in order to serve as a master lock therewith; and

Figure 11 is a rear elevational View of the assembled lock of Fig. 8, showing the cam on the rotating. barrel.

In electrical transmission and distributing systems, a standard arrangement of switching equipment includes a circuit breaker and controlling disconnect switches therefor, such as shown in Fig. l, in which a circuit breaker I6 is connected in the circuit l l between two sets of disconnect switches l2 and iii. The circuit H may be an in-coming line supplying energy to a bus I4 or it may be a feeder receiving energy from the bus. For the sake of simplicity, the circuit is shown as a single diagram instead of being illustrated with the usual three conductors of the circuit.

When any abnormal condition occurs on or in the breaker itself, that necessitates testing or adjusting or repair of the breaker, safety precautions require the opening of the disconnect switches i2 and I? so that the parts of the circuit breaker it may not become energized while the operators are working thereon. By means of an interlock system such as schematically illustrated in Fig. 1, the operator or repair man is compelled to open the breaker, to lock it open, and then, in turn to lock each set of the disconnect switches open before being able to re-operate the breaker mechanism itself. The interlock system for that purpose is illustrated as including a lock l5 at the breaker, two locks l6 and I1, respectively, at the disconnect switch l2, and two locks l8 and i9, respectively, at the disconnect switch [3.

The condition of each lock in the systems shown in Figs. 1 to 4 is indicated schematically by the small rectangles which represent the key slots or keys of the several looks. A solid black rectangle, as shown for lock H5 in Fig. 1, indicates that the lock bolt is withdrawn and that the key is in the lock. An open rectangle, as shown for lock IS in Fig. 1, indicates that the lock bolt is extended and that the key is out of the lock.

The lock l5 at the breaker co-operates with an interlocking element 2 I, schematically illustrated as connected to a bridging contact member of the circuit breaker, in such a manner that when the breaker is open, the interlocking element 2| is moved into position underneath the lock I5 so that the lock 55 may be operated to extend its bolt 22 to lock the interlock member 2!, and, consequently to lock the breaker contact against movement that would close the circuit through the circuit breaker.

The lock i5 is so arranged that its key can be removed only when the lock bolt 22 is in the extended position. Consequently, when the lock bolt is extended and the interlock element 2| of the breaker is locked against movement by the operator, the key may be removed from lock l5 and may then be used to unlock the lock I6 by withdrawing its bolt 23 from a slot 24 in an interlock element 25 associated with the disconnect switch ii. The disconnect switch [2 may then be moved to its open position, which movement will move interlock element 25 to shift a slot 26 into position underneath the bolt 2'! of the lock IT. The keys 99 of the respective lock units are retained against Withdrawal except when the locks are in the desired predetermined position of operation by means of a guide and positioning pin 9! carried by the keys adjacent the head thereof, the pin 9i entering a gate 92 in the cylinder casing when the key is inserted into the key barrel and moving into an annular channel 93 when. the key is rotated so that the key cannot be Withdrawn except when the key barrel is rotated to a position to align the pin 9| with the gate 92. This structure, illustrated in Figures 9 and 9a. is more particularly described in connection with the lock structures disclosed in my copending application previously referred to.

When the lock 16 was operated to withdraw its bolt 23, the key for lock it was locked against removal since the key can be removed from its look only in the extended position of the bolt. The look I! being similarly constructed, its key may be removed only when the bolt 2'! is extended, which locks the interlock element 25 against movement, and locks the disconnect switch 12 open. The key from look I? may then be employed to operate lock it to unlock that look and to withdraw its bolt 28 from a slot 29 in an interlock bar iii associated with the disconnect switch [3. The key in lock it cannot be removed so long as the bolt 28 is withdrawn. The disconnect switch may then be moved to its open position and lock l9 operated to extend its bolt 32 into a slot 33 in the interlocking bar 3!, locking disconnect switch It open. The key from lock I5 is then removable and may be used to unlock the lock l5 at the circuit breaker, as illustrated.

The circuit breaker It may theri be operated by electrically or mechanically operable mechanism without endangering the lives of the operators, since the disconnect switches H and I2 are open and isolate the breaker from any sources of energy.

The foregoing arrangement of interlock equipment, as illustrated in Figure 1 and in Figure 2, is suficient and satisfactory where access to the breaker is desired only when work is to be done upon the breaker itself. In order to permit operation of the breaker for phasing purposes, however, where external circuit connections might have been changed due to the repair of a faulty cable, only the disconnect'switch l2 be tween the breaker and the bus should be opened. Phasing equipment may then be connected across the terminals of the open disconnect switch l2 to determine whether the repaired cable has been connected to the proper phases, before the circuit is finally connected through to the bus. Obviously, the circuit breaker would protect such test operations and would open if improper cable connections caused excessive currents to flow in the circuit. This procedure is common practice for the phasing of incoming circuits before they are finally connected to the station bus.

To permit reclosing of the circuit breaker after only disconnect switch l2 has been locked open, an additional or auxiliary lock or key box 40 may be provided in order that a key may be made available to operate the lock at the circuit breaker without going through the entire sequence involving opening and looking out both sets of disconnect switches. The auxiliary key box 40 consists of a mechanism provided with two lock-operable devices 4| and 42, mechanically related, either by internal mechanism or by external mechanism, as schematically illustrated by the interlocking element 43, to permit and require the joint operations of both lock cylinders by the respective keys so that only one key can be removed at a time.

With such an arrangement, as shown in Figure 3, the key from lock [7, when removed, will serve to operate the lock cylinder 4! of the auxiliary key box 40 to withdraw its bolt 44 so that the interlock element 43 may be moved to position the slot 45a under the bolt 46 of the lock 42. The bolt 46 of lock 42 'may then be extended into the slot 45a, and the key removed from the lock 42 to be utilized to unlock the lock 15 at the circuit breaker to permit the breaker to be operated for phasing purposes. Disconnect switch l3 cannot now be unlocked.

In order to provide the same flexibility as is available with the interlock system of Figure 3, while obviating the necessity of, and the expense of, the auxiliary key box 40, my present invention contemplates making the lock l5 at the circuit breaker a master lock. Such master look may be operated not only by the key which it normally contains and which is available to operate lock I6 at the disconnect switch I2, but the master lock is also made to be operable by the key from the lock II.

This application is shown in Figure 4. When disconnect switch I2 is locked open, the key from lock I? may be removed to unlock lock ill at switch I3, or it may be returned to unlock the breaker to permit the breaker to be closed to put potential across the terminals of switch I2 for phasing purposes as described above. In the latter case the normal sequence cannot be carried further since the key of lock IT is now held at the breaker and cannot be used to unlock the lock [8 at disconnect switch IS.

A master lock so arranged and provided in an interlocking sequence can thus be made operable by more than one key, and operable independently of the normal prescribed sequence of interlocking operations, and permits a greater flexibility or control of the system at diminished cost, without in any way sacrificing the safety features for which the basic interlocking system is originally provided.

Any lock of standard type may be employed for the interlocldng systems, where the lock is provided with a rotatable barrel, or its equivalent, in which a group of elements are arranged to set up a combination operable by a particularly shaped key. Each lock for controlling any of the intermediate operations is arranged to be operable by only one key. The master lock which controls the operations of an element in the sequence whose operation may be desirable under different conditions can be arranged to be operable by more than one key, according to the specific sequence of operations desired under various conditions.

In order to provide for the master-lock feature in the interlocking system, any lock of the system may be made a master-lock to co-operate with other locks of the same type in the system, by providing proper combinations of the key controlled elements, such as tumblers, levers, or the like.

In Figures 5, 6 and 7, I have illustrated a lock of the tumbler type in which rotation of a keyreceiving barrel 5:? in the barrel cylinder 5| is controlled by a plurality of spring biassed tumblers, 52, 53, 5d, 55, 56 and 51. The tumblers 52 to 51, inclusive, may be made of various lengths and a large number of combinations may be established, which require a key 58 having proper contour to raise the tumblers out of the slots 59 in the rotating barrel to permit the barrel to be rotated by the key 58. As illustrated, the tumblers consists of two co-axial portions of such size as to be moved by the key to a position where the upper tumbler portion is in the outer cyiinder and the lower tumbler portion in the barrel. the barrel may be rotated. The rotating barrel 59 can then operate an external cam 60 to move the locking bolt in a predetermined direction.

When a lock of the foregoing type is to be employed as a master-lock, a lesser number of tumblers will be used. The patterns of the tumblers of the master-lock will correspond to the patterns of a similar number of corresponding tumblers of the standard lock or looks whose key or keys are to operate the master-lock. In this case, for example, the master-lock may have from one to five tumblers, which will be of the same pattern as the corresponding tumblers of the lock whose key is to operate the master lock. The remaining tumblers of the individual lock will be different so that the entire combination will be different, thus limiting the operation of each lock to its own key.

In Figures 3 and 10, I have illustrated a similar relationship between a standard lock and a master lock of the lever type, known commercially as the 4-way lock. The central rotating barrel 16, into which the operating key is inserted, is permitted to rotate, or is held against rotation, according to the positions of eight biassed pivoted levers "ll, arranged in four sets or pairs. Each lever is pivotally supported on a pivot pin 12 and is biassed by a spring 13 to a position where the front portion or toe of the lever extends outward into a slot in the outer cylinder housing, and the heel or back portion of the lever extends inward into the slot in the rotatable barrel. The barrel cannot be rotated In that position the two tumblers part,

while. any lever extends outward into the outer cylinder housing. When a key with the proper profile is inserted in the barrel, the levers are turned around their pivots i2 and withdrawn from the slots 16 in the cylinder housing l1 into the slots '65 of the barrel, and the barrel is thereupon permitted to be rotated by the key to operate an external bolt 78 through a suitable crank or cam on the outer end of the barrel 10.

When a lock of this type is used, the master lock is provided with a number of levers less than the eight levers of the individual lock, and having the same patterns as the corresponding levers in the standard lock unit whose key is to be able also to operate the master lock.

Thus by the provision of a lock in the sequence, with a combination of tumblers or levers less in number than those of a standard lock, and with corresponding contours, a special interlocking sequence may be established and superimposed upon the basic interlock system as a variation thereof. Obviously, one or more locks of the system may be made to serve as master locks.

Although I have illustrated the application of this master lock arrangement to an interlocking system provided for the protection and control of an electrical distributing system, it is not necessarily so limited, since the electrical system is shown here merely by way of illustration.

My invention is therefore not limited specifically to the particular arrangements illustrated, nor to the particular designs of the locks as shown, since they may be variously modified Without departing from the spirit and scope of the invention as set forth in the appended claims.

I claim as my invention:

1. A lock system, comprising a plurality of key actuated lock units operable in sequence, one of said locks being a master lock having means for retaining a key against release except when said master lock is in a predetermined position of operation, the other lock units each comprising a lock member operable by a key released by the operation of the next prior lock in the sequence, a captive key and means for retaining said captive key against release except upon operation of its associated lock member for operating the lock member of a succeeding unit, said master lock being also operable by the key released by the lock preceding the master lock in the sequence and by the key released by another and preselected lock unit of the system, whereby the predetermined complete or, alternatively, an incomplete predetermined sequential operation of all other locks must precede the operation of the master lock.

2. An interlock system for use with an electrical circuit including a circuit breaker in series with a line disconnect switch and a bus disconnect switch, said system including a key operated lock unit for the circuit breaker and a key operated lock unit for each disconnect switch, the lock unit for the circuit breaker being a master lock operative to look said circuit breaker open and having means for retaining its key against withdrawal except when said circuit breaker is locked open, said lock units of said disconnect switches each comprising a lock element for locking said switches closed, a captive key and means for retaining said captive key against release except when said switches are open, the key from said master lock being operative to actuate the lock unit of the bus disconnect switch to permit opening of the latter to release the captive key thereof, said captive key of the lock unit of said bus disconnect switch being operable to actuate either said master lock or the lock unit of said line disconnect switch and the captive key of the lock unit for said line disconnect switch being operable to actuate said master lock.

3. A locking system comprising a master lock having means for retaining a key against release when said master lock is in a predetermined position of operation, said retaining means being rem-- dered inoperative upon operation of said master lock to another position, and a plurality of key actuated lock units operable in sequence with said master lock, each lock unit including a captive key and a lock member operable by the key released from the next prior lock in the sequence, means included in each lock unit for retaining the captive key thereof except upon operation of the associated lock member, said master lock being also operable by the key released from the lock unit preceding the master lock in the sequence and by the key released from another and preselected lock unit of the sequence, whereby a key for actuating said master lock may be obtained upon the sequential actuation of all of said lock units in the predetermined complete sequence or alternatively upon the actuation of said lock units in an incomplete predetermined sequence.

4. A locking system for controlling the operation of related equipment comprising a master lock having means for retaining a key against release when said master lock is in a predetermined position of operation and for releasing said key upon operation of said master lock to another position, means associated with said master lock for placing some of said equipment in safety condition when said master lock is operated to key releasing position; a plurality of key actuated lock units operable in sequence with said master lock, each lock unit including a captive key and a lock member operable by a key released from the next prior lock in the sequence, means included in each lock unit for retaining the captive key thereof except upon operation of the associated lock member, the lock member of the lock unit succeeding the master lock in the sequence being operable by the key released from the master lock upon operation of the latter to place its associated equipment in safety condition, said master lock being also operable by the key released from the last lock unit in the sequence or by the key released from another and predetermined lock unit of the sequence, whereby said master lock must first be operated to initiate sequential operation of the other lock units in the system and whereby a key for actuating said master look as a terminal lock of a sequence may be obtained upon the sequential operation of all of said lock units in a predetermined complete sequence or alternatively upon the incomplete predetermined sequential operation of some of them.

RALPH L. KIRK.

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