US2130840A - Automatic reclosing circuit breaker system - Google Patents

Description

Sept. 20, 1938. L. w' DYER El AL 2,130,840

AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed Dec. 51. 1956 220 M AC.

WITNESSES: INVENTOR 5, L10 d N 0 er and WM y Patented Sept. 20, 1938 UNITED STATES PATENT- OFFICE AUTOMATIC RECLOSING CIRCUIT BREAKER SYST Application December 31, 1936, Serial No. 118,564

4 Claims.

Our invention relates, generally, to circuit breaker systems and more particularly to automatic reclosing circuit breaker systems.

The object of our invention, generally stated, is to provide an automatic reclosing circuit breaker system which comprises a simple system of inexpensive relays which may be economically manufactured and installed and which shall be simple, effective and reliable in operation.

Another object of our invention is to provide an automatic reclosing circuit breaker system which may be easily installed to operate circuit breakers already in use in the field without requiring any special apparatus to adapt such circuit breakers for use with the system.

Another object of our invention is to provide an automatic reclosing circuit breaker system which may be economically installed to operate circuit breakers already in use in the field by simple electrical and mechanical connections to such circuit breakers.

A further object of our invention is to provide an automatic reclosing circuit breaker system which may be constructed of simple and inexpensive relays and switching devices which are well known in the art and are reliable in operation.

A further object of our invention is to provide an automatic reclosing circuit breaker system which shall function to automatically reclose a circuit breaker at a predetermined interval after the opening of the breaker.

Another object of our invention is to provide an automatic reclosing circuit breaker system which shall function to reclose a circuit breaker on e2z1- piration of predetermined time intervals after each opening of the breaker.

Another object of our invention is to provide automatic reclosing circuit breaker system which. shall function to reclose a circuit breaker on ex piration of predetermined time intervals after each opening of the breaker and to render the reclosing system inoperative to reclose the breaker at a predetermined time after the first opening of the breaker in the event that the breaker con. tinues to reopen upon being reclosed.

Another object of our invention is to provide automatic reclosing circuit breaker system which shall function to reclose a circuit breaker at the expiration of a predetermined time after each opening of the breaker and to render the reclosing system inoperative to reclose the breaker at a time which shall 'depend upon the relative lengths of time that the breaker remains in the closed and open position in any series of openings of the breaker in which the lengths of time between openings of he breaker are relatively close to the length of time between opening and reclosing of the breaker.

Our invention is carried out, in its preferred form, by providing a control relay for the closing solenoid or other closing means of the circuit breaker and this control relay is energized through contacts which are closed at a predetermined time after the opening of the circuit breaker and opened when the circuit breaker is closed. The circuit of the control relay is controlled by a normally-closed time delayed relay, whose time delay is governed by the length of time the breaker remains open, for locking out the circuit breaker reclosing system to prevent such a number of circm't breaker operations in a given time period as might damage the breaker.

The apparatus comprising the automatic reclosing circuit breaker system of our invention is illustrated diagrammatically in the single figure of the drawing.

Referring to the drawing, circuit breaker it connects the load circuit l2 to the supply circuit H. The usual tripping device l3, which is controlled by an overload coil M on the load side of the breaker It, is provided to trip the breaker when an overload occurs on the line. The breaker is provided with a closing coil l5 which is cner gized through the contacts l6 and H of control relay it.

A contacting device it is controlled by the op crating mechanism of the breaker l0 so that it is biased to the open position when the breaker is closed, and is biased to the closed position when the breaker i0 is open througha loose mechanical connection illustrated diagrammatically by elemeat 20,

A time delay device ii is provided for delaying the closing of contact device It. This time delay device may be any means for delaying the closing of contact device after the means for closing the contact device has operated. This device is shown as a dashpot which will retard the closing of the contact device, but may be such a delayed action switch as is shown by the patents to Rhodes 1,773,697, August 19, 1930, or 1,353,850, September 2?, 1920. Any other delayed action switch may be used for performing function of delaying the closing of contact device IS.

The delayed action switch device l9-2l is preferably adjustable so that it may be set to obtain any desired delay between the opening of the circuit breaker l0 and the closing of the contact dev ce l9. Contacts 22 are connected to the ophit (ill) crating mechanism of the breaker I!) so as to be open when the breaker I0 is closed and closed when the breaker is opened.

A thermal current relay, generally designated by reference character 23, is controlled by contacts 22. This thermal relay comprises a heating element 24, a bimetallic element 25 and contacts The contacts are normally closed and are opened upon predetermined heating oi element 24. A latching device 21 is provided to lock the contacts 26 in the open position by engaging the bimetallic element 25 when it has moved the con tacts 26 to open position. A variable resistance 34 is provided in series with heating element 24 to vary the value of current flowing in heating element 34 and to thereby vary the time required to heat the bimetallic element 25 sufficiently to cause it to effect the opening of contacts 26.

The control power may be from the usual 220- volt, alternating current or direct current source shown in the drawing as conductors X and Y. The system as shown is operated on alternating current and has a rectifier 28 connected between the circuit breaker closing coil l5 and its control contacts l6 and ll to obtain direct current for operating the closing coil. This rectifier may be eliminated and the coil l5 connected directly to contacts I6 and ii if direct current is used for the control system.

The circuit for the closing coil of breaker extends from supply conductor Y, through conductor 29, contacts ll, rectifier 28, closing coil i5, contacts it and conductor 30 to supply conductor X. The circuit for the control relay it which controls the energization of the closing coil it extends from supply conductor Y, through conductor 3i, contacts iii, relay coil l8, contacts 26, bimetallic element 25, and conductors 32 and 3d to supply conductor X.

The circuit for the thermal current relay 23 extends from supply conductor Y, through conductor 33, contacts 22, adjustable resistance 3d, heating element 24, contacts 26, bimetallic element iii and conductors 32 and Elli to supply conductor X.

When an overload occurs upon the line it, tripping device it is energized to allow the circuit breaker to open to break the connection between the supply line i t and the load circuit ill.

The opening of the circuit breaker biases contacts iii toward the closed position and the closing of these contacts is delayed by the time delay device 2i. After the time delay determined by the device 2!! has elapsed, contacts iii close to complete the circuit through control relay The energization of relay it through contacts iii causes relay it to close its contacts in and [ill to energize closing coil in to reclose the breaker. Thus the circuit breaker it is reclosed at a predetermined time after being tripped by the trip device 63, this time being determined by the time delay of device it.

The reclosing of the circuit breaker iii causes contacts iii to open immediately, deenergizing ccil ic The deenergizing of coil it causes contacts it and ill to open and to thereby deenergize the closing coil in of the circuit breaker.

The system has now been placed in normal operating position and if the fault which causes the original tripping of the circuit breaker still exists. the breaker will immediately trip out through the agency of overload coil l4 and trip device l3 and the cycle of operation just described will be repeated. Each time the breaker opens, contacts 22 are closed immediately and remain closed for a time equal to the time delay governed by the time delay device 2| since they are closed so long as the circuit breaker is open. While contacts 22 are closed, a circuit is completed through elements 33, 22, 34, 24, 26, 25, 32 and 3t. When the circuit breaker i0 is reclosed, contacts 22 are immediately opened, breaking the circuit to the heating element 2t. Thus it is seen that the heating element 24 of the thermal current relay 23 is energized for the period that the circuit breaker is open.

If the circuit breaker l0 retrips immediately upon being reclosed, contacts 22 are again closed to energize heating coil 24 to cause further heating of the thermal current relay.

In order to limit the number of reclosures of circuit breaker l0, and to thus protect it from damage due to too great a number of immediate openings under the heavy load which is causing it to trip, the time delay of thermal current relay 23 is adjusted by means of adjustable resistance M to open contacts 26 after a predetermined heating of heating element 24 which is determined by the number of openings of the circuit breaker Hi. If it is desired to limit the number of openings of the circuit breaker to three, resistance 34 will be adjusted so that the current flowing through the heating element 24 for a period equal to slightly more than the time delay for reclosure of the circuit breaker will cause the bimetallic element 25 to open contacts W'hen bimetallic element 25 moves to a position to open contacts 26, it is locked by latch means 21? in a position to hold contacts 26 open. Thus the energizing circuit for coil 8 of the control relay is held open and automatic reclosure of the circuit breaker i0 is prevented until latch 27! is tripped.

The thermal current relay 23 may be adjusted by means of adjustable resistance 34 to cause any desired number of reclosures of the circuit breaker before rendering the system for reclosing the circuit breaker inoperative. This may be done by adjusting the resistance 34 so that the current through heating element 24 flowing for a period slightly greater than the sum of the desired number of open periods of the circuit breaker it will operate to open and lock open contacts 28. This is the condition that obtains ii? the circuit breaker immediately trips open after each reclosure.

If the circuit breaker stays closed after any reclosure, the opening of contacts 212? will deenergize heating element 2d and allow bimetallic element to cool to its normal temperature.

. it is understood that the thermal current relay and the time delay device 26 for delaying the closing or" contacts it] may be any device for performing the functions disclosed which are well known in the art.

Thus it is seen that we have provided a simple, inexpensive and reliable system for automatically reciosing a circuit breaker, which system will delay the reclosing of the circuit breaker a desired predetermined time after the breaker is tripped open and which will limit the reclosings of the circuit breaker to any desired predeter mined number.

We claim as our invention:

1. in an automatic reclosinp; circuit breaker system, a circuit breaker biased to open circuit position, latch means for holding the breaker in closed position, means responsive to predetermined abnormal conditions on the circuit to which the breaker is connected for tripping said latch means, a first circuit closer, means whereby said first circuit closer is closed while said circuit breaker, is open and open while said circuit breaker is closed, a second circuit closer, means for closing said second circuit closer a predetermined time aiter said circuit breaker is opened and 'ior opening said second circuit closer when said circuit breaker is closed, electromagnetic means for closingsaid circuit breaker, a thermal current relay having a heating element, a circuit comprising the contacts of said thermal current relay, the heating element of said thermal current relay and said first circuit closer for energizing said heating element, a circuit comprising said thermal current relay contacts, said circuit breaker closing means and said second circuit closer for energizing said circuit breaker closing means, and means for retaining said thermal current relay contacts in open circuit position.

2. In an automatic reclosing circuit breaker system, a circuit breaker biased to open circuit position, mechanical latch means for holding said circuit breaker in closed circuit position, means responsive to predetermined abnormal conditions on the circuit to which *the circuit breaker is connected i'or tripping said latch means, a first circuit closer, means whereby movement of said circuit breaker to open circuit position will close said first circuit closer and movement of said circuit breaker to closed circuit position will open said first circuit closer, a second circuit closer.

, means whereby movement said circuit breaker circuit for energizing said heating element comprising the contacts of said thermal current relay, the heating element for said thermal current relay and said first circuit closer, and a circuit for energizing said circuit breaker closing means comprising the thermal current relay contacts, said circuit breaker closing means and said second circuitcloser.

3. In a control system for a circuit breaker having an electrically actuated closing means, first and second back contact elements on the circuit breaker, said first back contact elements being time delayed in closing upon opening of said circuit breaker, a thermal current relay having normally closed contact elements, a control circuit for the breaker closing means comprising said first back contact elements and the contact elements of said thermal current relay, and a circuit comprising said second back contact elements and the heating element of said thermal current relay, said control circuit for the breaker closing means being operable to deenergize the closing means when said circuit is broken by the movement of said first back contact elements to open circuit position upon closing of said circuit breaker.

4. In a control system for a circuit breaker having an electrically actuated closing means, first and second back contact elements actuated by the circuit breaker, means providing delayed closing of said first back contact elements upon opening of said circuit breaker, a thermal current relay having normally closed contact elements, a first circuit consisting of said first back contact elements, the circuit breaker closing means, the thermal current relay contact elements connected in series circuit relationship with a source of electric energy, and a second circuit consisting of said second back contact elements which are opened when the circuit breaker is closed, the heating element of said thermal current relay and the contact elements of said thermal current relay connected in series circuit relationship with a source of electric energy.

LLOYD W. DYER. GAYNE D. GAMEL.

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