US2389613A - Polyphase protective system - Google Patents

Description

1945. R. P. DE ANTHONY POLYPHASE PROTECTIVE SYSTEM Filed June 30, 1944 2 Sheets-Sheet 1 A a Q INVENTOR.

Posse-Iv? DEA/VW/OA/r Nov. 27, 1945. R. P. DE ANTHONY 2,339,613

POLYPHASE PROTECTIVE SYSTEM Filed June 30, 1944 I 2 Sheets-Sheet 2 FIG. 2

INVENTOR. Posse-r2 05/ rwa/vr Patented Nov. 27, 1945 UNITED STATES PATENT orricu (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 1 Claim.

The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to improvements in protective systems for electrical apparatus, and more particularly to a protective system for interrupting the flow of current between a current source and an electrically operable apparatus through a plurality of electrical conductor lines, incident to the interruption of current flow in any one of the conductor lines.

An object of the present invention is to prevent continued operation of a polyphase dynamoelectric machine in the event of failure of any of the phases where such failure is insufficient to prevent continued operation on the remaining phases.

A further object of the present invention is the provision of simple and effective automatic circuit breaking means for a plurality of electrical operating circuits, each having an overload fuse device therein, including independent shunt circuits for actuating the circuit breaking means when energized, said shunt circuits being bridged across the fuse devices so as to be energized by failure of the fuse device to cause operation of the circuit breaking means to break all of said electrical operating circuits incident to the interruption of any one of said operating circuits by the fuse device therein.

A further object is the provision of a protective system for polyphase dynamoelectric machines, such as multiphase motors and the like, having a plurality of phase lines each protected by a fuse device, and connected to a current source and to the phase windings of the motor device, and including normally open circuit closing switch means controlling the current flow in all of the phase lines, movable .to circuit closing position, having a holding coil and an energizing circuit therefor provided with circuit breaking means and a plurality of operating shunt circuits for the circuit breaking means each bridged across one of the fuse devices in each phase line to energize one of the shunt circuits to actuate the circuit breaking means to break the holding coil circuit incident to interruption of the circuit in one of the phase lines by the fuse device in that line.

A further object is the provision of releasable locking means for the magnetic circuit breaking means for locking the same in circuit breaking position electrically actuated signal device for the magnetically operated circuit breaking means, adapted to b actuated incident to the energizing of the magnetically operated circuit breaking means.

A still further object is the provision of a simple and effective circuit interrupting device for breaking the main switch holding circuit of a conventional polyphase dynamoelectric machine control system; operable upon interruption of current flow in one of the phase lines by a fuse device in that line and controlled by a shunt circuit in that line around the fuse device to break the main switch holding circuit, releasing the main switch to cause interruption in the current flow in all of the phase lines between the electrical power source andthe polyphase dynamoelectric machine.

Other objects and advantages of the invention will become apparent from the following description, taken in connection with the accompanying drawings in which like reference characters refer to like parts on the several figures of the drawings.

Fig. 1 is a side elevation, partly broken away and shown in section, of my improved polyphase circuit protective device, showing the same connected schematically in a conventional polyphase dy iamoelectric machine starting and control circui Fig. 2 is a top plan view of my improved circuit breaker device.

Fig, 3 is a fragmentary sectional view taken g pprcliximately on the plane indicated by 33 of Referring more particularly to Fig. 1 of the drawings, the numeral I indicates schematically a polyphase dynamoelectric machine, such as a three phase motor having the phase winding or field coils 2, 3, 4 thereof connected respectively by phase lines 5, 6, I to one terminal of each of the circuit closing devices or switches 8, 9, l0. These switches are preferably of the gang or simultaneously operable, normally open type, having a common actuator I l and a closing and holding circuit including a closin and holding magnet coil IZ. Current is supplied from a conventional polyphase electrical source (not shown), through the phase lines I3, ll, l5, each protected by individual overload fuses or circuit breaking devices l6, ll, l8, connected to the lines I9, 20, 2|, which are in turn connected to the other terminal or contact of each of the respective switches 8, 9 and I0. Thermal relays I9a and lie are usually interposed in the lines 5 and l ahead of A still further object is the provision of an the switch contacts 8 and III for the purpose of tinue to operate on the-remaining phase lines in,

an unbalanced phase relation causing excessive heating, and, if the other phase lines are not in"- terrupted very promptly, serious damage to the motor or other apparatus being operated may tion, which may be the case where the motor load is light, this vibration and heating-will do irreparable damage to the motor. Also it is necesate the breaker device 3| to interrupt the starting and holding circuits.

, In the event of an excessive overload or short circuit in any one of the phase lines or the dynamoelectric device connected thereto (shown in the result. Should the bi-metallic relays iailto funcsary that these relays be of the proper rating for the particular motor used, which requires :a different size relay when a different-size motor is" operated in the circuit.

Customary stop and start push buttohs 22 and 23 'are'disclosed, which are ordinarily'conneoted by a" conductor 25 (shown in dotted lines) to one sweet the holding coil it by the wire Ito, and to one side of the, start and stop pushbutton contacts by, abondlictor 'ZbLfDepreSsiOn of the starting button 22'clo'ses a holding circuit through the'wires 21, 2: and ruse is or the feed wirefle while current from the feed wire 13 passes through the fuse is, conductor is; conductor we; holding coil I2, conductors no, 25 and 23, through the Switch contacts 22d 'of the starting'switch 22 and throng-lithe conductors 21, 2'1 and fuse IE t the other main feedvvire to complete the. Starting circuit. As before indicated; thiscircuit is a conventio'nal polypha'se motor starting circuit, and is inclosed by thephantom line'in Figpfl. My protective modifies thisc'ircuit' in ainanner later to be described. 7 When the starting coil |'2is energized, this causes thecoininon switch actuator! i for the normally o en phase line switches to close, estab lishing the phase circuits through the lines l3,

drawings forthe purpose of illustration only as a three phase circuit), one of the thermal responsive circuit interrupters or fuse elements l6, I"!

or IS in the overloaded line will function to inthe-fuse device in that line, energizing the circuit 38 adapted to be energized as an incident to the circuit breaking o eration breaker 3|. 7 I p l v More specifically describingthe circuit breaker of the circuit 3|, I provide a, plurality of end supports 39, 4c,

I4 and I5 to the field windings l; 2 and 3 or the dynam elcctric machine i. closing or the switch it establishes the holding circuit front the main line It through the iacohductcrs' 2 i; 2112; thermal relay zl-c, switch in, co'ricluctors 1 and 28 through the normally closed contacts 23dof the sto switch 23 and conductor i'inrto' the eon-V ductors 26 25 and I204, back to the st ting and holding coil l2. Completing this conventional starting and holding circuit, current then hows from the starting and holding coil l2 through the conductors 9a, 19, ruse-device" to the other main feed line l3. p

In my improved polyph'ase protective system I provide an electrically operable circuit breaker".

indicated generally at3|, later to be d scribed in detail,- having circuit breaker contacts interposed in the starting and holdi g coil circuits above described. The conductor 25 is rcihovedfland the conductor 12a i's'connected by a wire 32 to one side of the circuit breaker contact means of the o carrying a co ventional laminated core ii fixed therein. A plurality of exciting co ls 42,43 and 44 are superimposed on the" core, as best seeh'in Fig. 1, each coil being connected niche of the shunt circuits 34, 35 and 36. An additional induction coil 45 is disposed between the two sup ports 39,40 next-to the core ahd connected in the independent energizing circuit 38 for the sig: nal device 31 I p f The opposite ends of the core member 4| are bridged b Li-shaped contact supporting ' mem bers 46 and 41, carrying insulated electrical contacts 48, 49;.5c and 5|, Contact 48 is connected to the con'ductors32 leading from. the holding coil i2 while the contact 5| is connected to the conductor 33 leading to the stop and start switch contacts 23a and 22a. 1

Arrnature members 52 and 53 are movabiy disposed in the U=shaped portions or the respective end members lfi and Hon fixed guide rods-54' and 55, the ends of' the rods54, 55 having their ends disposed'in suitable sockets in the respective end suppo1ts'39 and! and in the U-shaped sup ports 46 and 41. Each armature carries a pair of electrically connected contacts, indicated at Q56; 56 and 51, 5'! in Fig. 2, adaptedto engage the respective stationary contacts 4-8,'49' and SDI- 5!, when the armatures arespaccd away from the ends of the core member H. Eesilient'actuating means 'inthe forrn of coii springs 58 are disposed on the guide rods 54, 55 between the end supports 3 9 and 40 and the armatures 52 and 53 to yieldably-urge the armatures' away from the core; and to move theiespective circuit ciosingfcon; tacts into circuit closing engagement 1 Locking means are provided for releasably hold ing the circuit breaking contacts in circuit break: ing relationas shown in dotted lines in Fig,- after the armatures have been moved toward'th endsofthecore 4|. p 7 A bridging conductor 59 connects the stationary contact 49 to the stationary contact 50, pro viding the circuit breaker device with four circuit breaking contacts connected in series, any one of which when moved to circuit breaking position, due to energization of the core by one of the shunt circuits in the phase lines, will interrupt the holding circuit, permitting the switch actuator to move to circuit breaking position and interrupt the phase current flowing to the motor field coils.'

The releasable locking'means for holding the armatu'r'esin circuit-breaking positions comprises locking abutments, each the form of a pin or rod 60, fixed to and projecting from the face of each armature 52, 53, intermediate the spaced armature contacts thereon. These abutments or pins 60 are slidably received in the guide recesses 6| formed in the U-shaped cross members 46 and 41. Lateral passages 62 extend vertically into the guide recesses 6|, each carrying a locking detent member 63, adapted to rest against the side of one of the locking rods or pins 60 when the armatures are in circuit closing position.

Movement of the armatures toward the core member axially displaces the locking pins 6|) out of the path of the locking detent members 63, allowing the detent members 63 to move upwardly into the path of return movement of the locking pins 60, blocking the return movement of the armature members under influence of their actuating springs 58, toward the starting and holding circuit closing contacts 48 to The locking detent members 53 each have a U-shaped operating extension or handle portion 630, extending upwardly through a bore 64, parallel to the passage 52 in the U-shaped support, and the extremities of these extensions are pivotally connected, as indicated at 65 and 65, to the opposite ends of a common resetting bar member 61 having a resetting or operating button 68 centrally mounted thereon. Guideways or'slots 69, 69 are formed in the upper edges of the end supports 39 and 45, and in the upper edge of a separator plate 10, for receiving the resetting bar member 61 and maintaining the same slidable in a vertical plane. Each operating extension or handle 63a is provided with an enlarged abutment H intermediate its length for engagement with one end of a release coil spring 12. These springs are interposed between the abutments H and the top surfaces of'the U-shaped support or end members 46, 41 to urge the respective detents upwardly into locking position.

When one of the armatures 52 or 53 is attracted, incident to energization of one of the shunt circuits 34, 35 or 36, the pin 50 carried by the armature is moved out of the path of the locking pin 63. The spring 12 on the vertically movable locking pin extension 63a raises the locking pin 63 into the path of movement of the armature carried lockin pin 60, preventing return of the said contact carrying armature 52 or 53 to circuit closing position. This locking movement of the pin or pins 63 elevates one or both ends of the release bar and its resetting button, depending whether one or both armatures have been actuated.

'Io reestablish the phase circuits to the polyphase dynamoelectric machine, the reset button 68 is first depressed, withdrawing the vertically movable locking pins 63 out of the path of movement of the locking rods 60 carried by the armatures 52, 53. The springs 58 on the guide pins 54 and 55, as best seen in Figs. 2 and 3, now space the armatures away from the poles of the core member. 4| andv intojcircuit closing position with respect to the starting and holding coil contacts 49 to 5| and 56, 51. Thismoves the locking pins 60 into'the path of return movement of the vertically movable locking pins 63, thus lock-. ing the reset bar and button in depressed position with the circuit closed, as'shown in full lines in Fig. 1. Assuming that the cause of the overload in the phase line has been remedied, and the blown fuse device in the previously overloaded line has been replaced, depression of the starting, button 22 energizes the starting coil I2, closing the switches 8, 9 and It to all of the phase lines.

The signal device 31, as disclosed in the drawings, comprises a support 15 having a drop type annunciator lever 16, carrying an annunciator plate 11 having an appropriate signal legend thereon, such as Fuse out. A spring loaded release latch in the form of an armature I8 is pivoted to the support 15 to engage the end of the legend plate 11 holding the same out of view until released by an electro-magnet device 19 electrically connected in the closed induced current circuit 38 having the induction coil 45 of the circuit breaker 3| also in the circuit. Any current flowing through any of the shunt circuits 34, 35 and 36, due to the blowing of a fuse device in one of the phase lines IS, IT and I8 energizes one of the respective magnet coil 42, 43 or 44 of the circuit breaker device 3|, attracting one or both of the circuit breaking armatures 52 or 53, toward the ends of the core. The locking pins 60 being displaced out of the path of the vertical locking pins 63, these latter .pins move across the guide bores 6| for the locking pins 60, preventing the return of the armature or armatures to circuit closing position until the reset button 68 is depressed.

A voltage is induced in coil 45 causing an induced current to flow in the signal circuit 38, energizing the magnet 19, displacing the latch I8 to drop the signal 1'! to the dotted line position in Fig. 1.

Since the fuse devices I6, l1 and I3 are all of comparatively lower impedance while the shunt circuits 34, 35 and 36 of the breaker device are of relatively high impedance, my improved protective system and apparatus may be employed substantially without change in any conventional polyphase dynamoelectric machine control circuit, the only requirement being that overload fuse devices of the proper ratings be provided for the motor or other operated device being used be placed at l6, l1 and I8 in the respective phase lines I3, I4 and I5.

The thermal relay devices |9a and 2 lo are disclosed as a part of a conventional polyphase dynamo-electric machine starting and holding circuit,

but in my improved protective system these thermal relay devices may be dispensed with since they are unnecessary to the operation of the system.

The circuit breaker device 3| is preferably housed in a suitable metallic housing or case (not shown) having an opening therein for access to the reset button 58 while the signal indicator 31 may be located at any desirable remote location.

Although one specific embodiment of the invention has been shown and described it will be understood that the invention is capable of modification, and that changes in the construction and arrangement of the various cooperating parts may be made without departing from the spirit of the invention as defined in the accompanying claim.

I claim:

In a polyphase dynamoelectric machine protective. apparatus; a. plurality of. phase lines adapted to be c nnected; to a pcl-yphase d-ynamoelectric machine, a thermal responsive element in each phase line for interrupting" current flow incident to overload in that line, magnetically operable. circuit closingand holding. means; for closing: all phase v circuits and releasably maintaining the same: in

closed position including a closing: circuit and a holding. circuit for energizing said magnetically operable circuit closing. and. holding means, a support, a core, an independent exciting coil on; said core'for each phase lineconnected in shunt across the thermal responsive overload device in that line. an electrically operable signal device: and; an additional induction, coil onsaid core; having; a closed operating circuit including, the.- electrically operable signal; device, circuit closing armature assaeia movably mounted: to be actuated by said core, cooperating circuit closing: contacts carried by said: armature and support: disposed: in said holding: circuit; spring. means between the support and; armature to yieldablst space the same from said core, with the clbsing' contactsengagmg: each other to close the holding circuit, and releasable latching means between the support and armature for holding the armature andg con.-

" tacts in circuit breaking positionafter' attraction thereoi by said core incident to energization of one: of. said shunt circuits; due; to current interruption ofi current. flow inv one of said phase lines by the thermal response overload element in that 155' Til-16.,

ROBERT P. DE ANTHONY.

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