US863791A - Protective device. - Google Patents

Description

PATENTED AUG. 20, 1907. L. EMERY.

PROTEGTIVE DEVICE.

APPLICATION FILED JAN. 10, 1907.

2 SHEETS-SHEET l iniijjiliiilil WITNESSES PATENTED AUG. 20, 1907.

L. EMERY. PROTECTIVE DEVICE.

APPLIOATION FILED JAN. 10, 1907.

2 SHEETS-SHEET 2.

\NVENTEIR LUREN EPIER v iTNE35E5 MKQ JOQ tinigrnn STATES LOREN EMERY, or

SCHENEGTADY, NEW YORK, ASSIGNOR TO COMPANY, A GORPORATlON OF NEW YORK.

GENERA L ELECTRIC PROTECTIVE DEVICE.

To all whom it may concern: 4

Be it known that I, LoRnN EMEnY, a citizen of the United States, residing at Schenectady, county of Schenectady, State of New York, have invented certain new and useful Improvements in Protective Devices, oi which the following is a specification.

My invention relatesto protective devices for electric circuits, and its object is to provide a device which will operate to open the circuit upon either an overload or a reversal of energy; which may be arranged with a timelimit retarding device operative on normal overloads,

I but inoperative on an excessive overload, or on a rever sal'of energy;,which may be used on either direct or alternating-current circuits; and which is reliable under all conditions. 1

Many devices, which have been proposed heretofore I for the protection of circuits against reversecurrent,

fail to operate upon a reverse-current of so great a magnitude that the voltage of the circuit falls far below its normal value. In order to prevent such failure, I arrange'the device'so that even if the voltage should fall entirely to zero, it would still be operative upon either overload or reversal of energy. I accomplish this by providing two relatively movable members, one provided with a series winding, and the other with differential shunt and series windings. On normal loads the shunt winding on the second member overpower-s the series winding, but on an overload the series winding overpowers the shunt winding and reverses the torque on the other member, while upon a reversal of energy the shunt and series windings are no longer differential, but cumulative in producing a reversal of torque in the device. In either case the device is not dependent on the shunt winding but will operate upon a heavy how of current in the series windings, even though the shunt current falls to zero.

For ordinary overloads it is desirable that the device should have a time-element in its action, but upon oxcessive overloads or upon any reversal of energy, it is desirable that the action of the device should be instantaneous. To give this result I provide a retarding device which is normally operative, but which is rendered inoperative by an abnormal fall of voltage, or upon a reversal of energy. I accomplish this by providing an armature shunting the potential winding, and normally held attracted by this winding, and provide means controlled by this armature for rendering the retarding means inoperative when the armature is al- :lowed to fall My invention will best be understood by reference to the accompanying drawings, in which Figure 1 shows a front elevation of a protective device arrangcd in accordance withnry invention; Fig. 2

Specification of Letters l atent.

0,1907- Serial No. 351,676.

Patented Aug. 20, 1907.

shows a side elevation of the same; and Fig, 3 is a diagram of the circuit connections.

Referring first to Fig. 3, jsrcpresents the circuit to be protected. It is shown as a branch circuit from the main circuit B A suitable switch Ofadaptcd to open the circuit A is provided with a. trip-coil c, which iscontrolled by the protective device. The protect ive device comprises a pivoted armature D, carrying the winding E, which is supplied from the series transformer l" inserted in one of the conductors of the circuit A.

G represents a field magnet provided with a winding H, which is also supplied from the scrics transformer F, and a winding I, which is .supplicd .t'rom the shunt transformer .l'.

, K represents a pivoted armature, which magnetically shunts that part of the field magnet G which carries the shunt winding 1, and is normally held in raised position, as shown, by the flux due to this winding. The

pivoted armature D carries an arm L, which is prov armature D is rotated in a clockwise direction. The

arm L is connected to a retarding device N, which is shown as of the wellknown bellows or diaphragm type. This device has an opening in its base, which is normally closed by the valve 0, which is normally hold raised by a spring 0, shown in Figs. 1 and 2 As long as valve 0 is closed, the device N acts to retard the movement of the armature D, but when valve 0 is lowered, the rctardingdevice is rendered inoperative.

The lowering of the valve 0 is brought about by the falling of the armature K.

The operation of the device is as follows: The windings H and I on the hold magnet normally oppose each other; the winding I being the stronger for ordinary loads. Consequently the torque on the armature D is determined by the current in the shunt winding l, and is normally in a counter-clockwise direction. Upon an overload the increase of current in winding 11 will cause it to overpower, winding 1, so as to reverse thctorque on the armature D and cause it to close the circuit'of the trip-magnet. If the directional energy in the circuit A reverses, the current in winding II will assist the current in winding 1, while the current in winding E will be reversed, so that the torque on the armature D will be reversed and it will be moved to close the circuit of the trip-magnet. Thus, the device operatcs'either upon an overload or upon a comparatively small reversal of enorgy' During ordinary overloads the device N operates to retard the movement of the armature D, so as to give the timeelemcnt which is ordinarily desired in overload protective devices, but upon the occurrence .of a short-circuit, which would loo lower the potential. and eonseqnentlv the current in l winding l armature K would he allowed to lalL pulling down the valve 0. and rendering the retarding deviee 3 N ilitllfiil'liilvt. Similarly. upon a reversal of energy, if the air-gap hetween the armature D and the iield magnet G is small the reluetanee ol'i'ereil hy the magnetic eireuit passing through the armature D to the shunt llux may he made much smaller than that offered by the nrgnetie circuit passing through the armature K. so that the greater part of the shunt flu); will be diverted from the armature K. 'lhus, the armature K can he caused to drop on aeomparatively small rever al of energy and render the retarding device N inoperative.

The preferred consiruetion oi the deviee is shown in Figs. l and 2. The several parts are lettered as in Fig.

All the parts are the same as in Fig 3. with the addition of the spring 0 for holding the valve i) normally closed and a needle-valve i tor adjusting the action of the retarding devit-e N in ihe well-known manner.

What I elitim as new and desireto secure by Letters Patent of the United States, is,"-

t. in eoinhinatinn with an eleetrie eirenit. a proteetive d viee comprising relatively nntvnhle memb rs, one provided wirh diii'erential shunt and series \vindii and the other with a series .vindiue. and means operative upnn a lative movement o1- said for opening said lill.

r memhers L. in eomhination with an i e trit' eirenit. a proteetive deviee eoinprising relatively movahle inemhers one provided with ditferential shunt and series windings and he other \\'iih a series. indium menus operative upon a relalive movement tit' said memhers i'or ep ning' said eirenit. and means for retarding Siltl relative inovement.

iii In eomliii'ation with an eleetrie eireuit, a proteetive device etnnprang relative]; movahle ineintters. one provided with diti'erential shunt and series windings and the ether with a series \\'llltlili' i. means operative upon a relaiive movement of 'd niemhersl'or upetliml, said eirenit. means for retarding said relative mov ment. and means for rendering the retarding means innperative upon an ahnorntal t'ali of voltage in said eireuit.

4. In \ftmhinntion with an tllt'll'it' ('lttftiii, a proiet-tive l l l i t l t l l l i l i l devit-e comprising a pivoted armature having a series winding and a iield magnet having ditTerentlal shunt and series windings and means operative upon the movement id armature for opening: said eireuii.

3 ln eoinhi ition with an electric circuit, a prot ive deviee euinpr. ng a pivoted armature having: a series winding and a tield magnet having difl'erential shunt and series windings. eoniaets eontrolled by said armature. a magnet in eirenit with said contacts, and a switch eon trnlletl li said magnet adapted to open saidcircuit'.

ti. In eomhination with an electric circuit, a proieetive device Ctilttiiti-Sing a pivoted armature having a series winding and a field magnet having tditferential shunt; and series windings means operative upon the movement of said armature for openint, said eireuit. and means for retarding; the movement otsaid armature.

T In ("oinhination with an eleetrie eireuit. a protei-tive deviee eoniprising a pivoted arnmttn'e having a series winding and a tield nine-net having dili'erential shunt and windings spared apart thereon. nit-ans operative tpon a movement of said armature for opening said eir- (llii. means for retarding the movement of said armature. and an armature nia;.rnetieall shunting that portion oi' the iield magnet carrying the slmnt winding and eontroh ling said retarding means.

s. In eoinhination with an ele'etriteireuii. a pruteetive devit'e operative to open said tll'titil upon an overload and upon a reversal of ene therein means for retarding ihe operation at said deviee. and means for rendering said retarding means inoperative upon an ahnormal t'all voltage in said E-irt-nit and upon a reversal of energy therein.

.t. in eoinhinution with an eleetrie eireuit a proteetive deviee eoniprising relatively muvahle memhers. one prtr \"ided with dill'erenlial shunt and series windings and the other with a series windina. means operative upon a rela tive movement inemh for opening said ein'uit, means for retarding said relative movemenh and means series of said said retil

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