US2424447A - Appliance for closing a switch for parallel connection of two networks or a network with incoming generator - Google Patents

Description

July 22, 1947. A. GANTENBEIN m AL 2,424,447

APPLIANCE FOR CLOSING A SWITCH FOR PARALLEL CONNECTION OF TWO NETWORKS OR A NETWORK WITH INCOMING GENERATOR Filed Feb. 2, 1945 iatented July 22, 1947 PARALLEL CONNECTION OF TWO, NET- WORKS OR A NETWORK -WITHIINCOMING GENERATOR Andreas Gantenbein and .1656 Jackie; Zurich,

Switzerland,

assignors to: Mascliinenfabrik Oerlikon, Zurich-Oerlikon, Switzerland Application February 2, 1945, SeriaTNo, 575,842 In Switzerland November 19, 1943' 11 Claims. (01. 171-118) Thepresent invention relates to a new and improved" device for closing: a switch for the connecting in parallel of two alternating current networks-or of alternating current networkwlth an incoming generator. Connection inparallel of alternating current'systems' with comparatively: greati-difierences' of frequencies'is only possiblewhen the time interval associated with the connecting operation, namely the time constant of the switch is taken into consideration by a certain angle of advance which corresponds to the momentary diflerence in frequency between the two networks, uso that closing of the breaker contacts takes placeat zero phase displacement. The different appliances in-use up to the'present time have many disadvantages, their construction is complicated: and they are unreliable in operation;

The object o-f-the inventionisto provide anew, simple and reliable arrangement of a' device which allows the actual closing of the breaker contacts-r of the' two networks to' takeplace at phase coincidence;

A further object" ofthe'invention: consists: in the provision of an appliance for parallel connection, in which theconnection takesplace'at the correcttime when phasecoinciden'ce has-been established; whereby at'the sarnetime', however; the difference in frequency'm'ay'vary withinpredetermined adjustable limits; Theinventionwillbe better understood from the following descriptionrtaken in connection with the accompanying drawings in" which a device for connecting" in parallel-twonetwork s is shown in adiagrammatical manner.

In the 'drawing-a-cont'actA is rotatably mounted'on the shaft of-a'syi'ich'ro-nos'cope the speed ofrotation of which is equal to the *difierence of frequencies between the two networks, it alsoindicates' the instantaneous relative phase position' of the incoming generator. At the same time a second contact-B, arranged I concentrically with A; moves at a spee'd that is directly proportional to the difference of frequencies between the'two networks. Whenn'ow contact A init-s travel slides over the contact B, electrical contact le established between them; the operation of:closin'g'thebrealier switchstarts, with due regard' to the timeeleinent and the angle of a'd-- vance'required due to'the particular closing time constantof the breaker switch, the actual closm 01' the breaker 'coritacts -occurringat zero phase 'displacem'ent; r k

The two networks I and'i canf-be connectedin arallellby-means of -th'e bleakerswitch3'. A

24 synchron'oscope"1 is connected with both networksthr'ough the two transformers 5 and 6. A pointer arm 24" with a rolling contact A is rigidlyco'nnect'e d to" the rotatable shaft 28 of the synchronoscope 1.- The rolling contact A isin continuous engagement with the larger circumference of a stepped pulley 23 and is adapted to conductively en'gagea contact Bmounted at one point of thi's' circumference. The stepped pulley 23' is freely rotatably mounted on the shaft 28 and itssr'n'aller diamete'rstep is engaged by an endless belt 22-pa'ss'ing also over another stepped pulley l4 having one of itssteps engaged by a belt 30 the parallel ends of which are secured eachby a spring l5 to ail-anchor bar Hi; The belt '30 and the springs l-5' yieldingly' resist rotation of the pu'lleys'M -and-23 'andtry to maintain andreturn the same to a pb'sit'ion'in which the contact-B onthe pulley 23 is in" a certain rest position 0 as indicated by a pointer 25 secured to the pulley '23 and pla'ying over a scale on a stationar dial Z EI' The S opp d pulley M is fixedly m'oun'te'd o'n a rotatable control shaft 29 0f an eddy current coupling as will appear pres-' entlyp y m Thesha'ft ZB liasrigidIy secured thereto a gear 8--which meshes with a gear fixed'to the rotor shaft 3 or an electi e-magnetic eddycur'rent slip coupling; This electromagnetic-slip coupling consists"essentially of arotor shaving solid poles anda' cylihdricalstator' I ll provided with an ann'u'lar 'eXeiting 'ccil H'; The rotor 9 is driven by niean's ofithe gears 8"and' 8dfrom the shaft 28' of tl'i'e'synchr'oiioscope l. The coil 32'is energized" with" direet' current' by the lines I3 containing a; regulating resistance l2; An aluminum drum" l l which-is fixedly secured with one of its-ends to the previouslyniention'ed rotatable control shaft 29': extends freely'movable-into the air gap formed between the'sta't'or bore and the rotor 9. The aluminum drum 1 l iservesas' an inductor in which are produced eddyrc'urrents'when the exciting coil 3-2 is energized and the rotor 9 is rotated by the shaft 28 and'the g6als8and 8a. The eddy currents fora predetermined excitation are proportional to the number of revolutions of the r0- tor Q'and the-shaft 28--respective1y, and. are also proportional to the counter torque acting on the aluminum drum IL. and derived from the belt andspring assembly 30, I5 which, as mentioned previously, resists yieldingly any rotative movem'ent'oi'the" stepped pulley l4 fixedly secured to theshaft 29. v

The degree of angular displacement of the drum" l l andoftheconta'ct B from its/normal zero position for a predetermined excitation of the coil 32 is therefore a function of the speed or number of revolutions of the shaft 28 of the synchronoscope, or in other words, it is a function of the difference in frequency between the two networks.

A third step of the stepped. pulley I4 is provided with a contact sector I! of a frequency limit control device. Two contact rollers l9 are in continuous rolling contact with the circumference of the third step of the stepped pulley and in certain positions of the latter are both in conductive contact with the contact sector ll. The rollers 19 are adjustable along stationary conductor rails l8 arranged concentrically about the pulley l4 and are provided with pointers 20 indicating the adjusted position of the rollers IS on a stationary dial 2|. The contact B is conductively connected by a lead 35 with the relay 4 which when energized will actuate the breaker switch 3 and thereby the two networks I and 2 will be connected with each other in parallel. The contact roller A is conductively connected by the pointer arm 24, a Sliding contact brush 35 and a conductor 31 with one of the two conductor rails 18. The other conductor rail 18 is connected with the relay by a conductor 38.

From the above described circuit connections it is obvious, that the relay 4 can only be operated to close the breaker switch 3 When firstly, the contact roller A engages the contact 13, and secondly, when at the same time the contact sector I! is engaged by both rollers H3.

The adjustable resistance I2 is employed for changing the excitation of the coil 32 so that the angle ofadvance can be adjusted to correspond to the time constant of the breaker switch 3 so that the latter is automatically closed at the very moment the phases of both networks I and 2 are coincident with each other.

The mode of operation is as follows:

If the prevailing difference of frequencies between the two networks is greater than that predetermined by the adjustment of the rollers l9 along with their respective rails [8, the torque exerted by the drum II will be sufficiently great to cause the sector IT to rotate out of engagement with one of the contact rollers [9. The relay controlling circuit is interrupted and closing of the breaker contacts cannot take place. As soon as the frequency difference becomes smaller and comes within the predetermined permissible limits, both rollers I9 will engage the sector i1. Connection can then be established to close the breaker contacts when contact B comes into contact with A during its rotary motion.

The angular deviation of the pointer 25 on the pulley 23 from the zero position on the dial 26 indicates the momentarily prevailing frequency difference. This deviation corresponds directly to the angle of advance and the time factor. The angular deviation of the pointer 24 carrying the contact A from the pointer 25, however, indicates the momentarily prevailing difference in the phase position between the two networks.

This arrangement can be improved by duly taking into consideration the momentary difference of acceleration of frequency of the two nets. This can be accomplished by adjusting the anchor bar l6 of the springs IS, the bar is moved horizontally either to the right or to the left, depending on the sign of the acceleration-difference.

The electric synchronoscope can also be replaced by two synchronous motors and a mechanical differential gear.

What it is desired to secure by United States Letters Patent is:

1. In a device for closing an electric switch for connecting two alternating current networks in parallel, a shaft rotating with a speed corresponding to the difference in frequency between the two networks, an electric contact radially spaced from said shaft and carried by a member fixedly secured to said shaft, a second electric contact arranged in the path of movement of the first mentioned contact, electric circuit means connected with said two contacts and adapted to cause said electric switch to close when said two contacts engage each other, and means for adjusting said second electric contact concentrical- 1y about the axis of said shaft in accordance with the frequency difference between said two networks, said means being actuated by said shaft and including a control device arranged in said electric circuit means for preventing the closing of said electric switch as long as the difference in frequency between the two networks exceeds a predetermined value.

2. In a device for closing an electric switch for connecting two alternating current networks in parallel, a synchronoscope having a shaft rotating with a speed corresponding to the difference in frequency between the two networks, an electric contact radially spaced from said shaft and carried by an arm fixedly secured to said shaft, a second electric contact arranged in the path of movement of the first mentioned contact, electric circuit means connected with said two contacts and adapted to cause said electric switch to close when said two contacts engage each other, and means for adjusting said second electric contact concentrically about the axis of said shaft in accordance with the frequency difference between said two networks, said means being actuated by said synchronoscope and including a control device arranged in said electric circuit means for preventing the closing of said electric switch as long as the difference in frequency between the two networks exceeds a predetermined value.

3. In a device for closing an electric switch for connecting two alternating current networks in parallel, a shaft rotating with a speed corresponding to the difference in frequency between the two networks, an electric contact radially spaced from said shaft and carried by a member fixedly secured to said shaft, a second electric contact arranged in the path of movement of the first mentioned contact, electric circuit means connected with said two contacts and adapted to cause said electric switch to close when said two contacts engage each other, means for adjusting said second electric contact concentrically about the axis of said shaft in accordance with the frequency difference between said two networks, said means being actuated by said shaft and including a control device arranged in said electric circuit means for preventing the closing of said electric switch as long as the difference in frequency between the two networks exceeds a predetermined value, and means associated with said second contact adjusting means for angularly shifting said second contact away from a normal zero position in addition to the angular adjustment effected by said shaft for considering the phase displacement due to the time constant of said electric switch and insuring a closing of said switch at phase coincidence.

In a device for closing an electric switch for connecting two alternating current networks in parallel, a shaft rotating with a speed correspondingto-the difference in frequency between the two networks, an electric contact radially spaced from said shaft and carried by an arm fixedly secured tosaid shaft; 3, second electric contact arranged in thepath of movement of the first mentioned, contact, electric circuit means connected with said two contacts and adapted to cause said electric-switchfto close when said two contacts engage: each other, and means for adjusting said second'electric contact concentrically about the axis of said shaft in accordance with the frequency difference between said two networks, said means comprising an electromagnetic slip clutch provided with a pole shoe carrying rotor, a gear connection between said shaft and said rotor, a stator provided with a variable excitable field coil, a cylindrical metallic drum loosely rotatable in the air gap between said rotor and said stator, means for transmitting the rotative movement of said drum to said second electric contact, and a control device arranged in said electric circuit means for preventing the closing of said electric switch as long as the difference in frequency between the two networks exceeds a predetermined value.

5. In a device for closing an electric switch for connecting two alternating current networks in parallel, a shaft rotating with a speed corresponding to the difference in frequency between the two networks, an electric contact radially spaced from said shaft and carried by a member fixedly secured to said shaft, a second electric contact arranged in the path of movement of the first mentioned contact, electric circuit means connected with said two contacts and adapted to cause said electric switch to close when said two contacts engage each other, and means for adjusting said second electric contact concentrically about the axis of said shaft in accordance with the frequency difference between said two networks, said means comprising an electromagnetic slip clutch provided with a pole shoe carrying rotor, a gear connection between said shaft and said rotor, a stator provided with a variable excitable field coil, a, cylindrical metallic drum loosely rotatable in the air gap between said rotor and said stator, spring actuated means for resisting the rotative movement of said drum, means for transmitting the rotative movement of said drum in excess of that compensated by said spring actuated means to said second electric contact, and a control device arranged in said electric circuit means for preventing the closing of said electric switch as long as the difference in frequency between the two networks exceeds a predetermined value.

6. A device as claimed in claim 4, including a pointer connected with said second contact and a stationary dial having a scale associated with said pointer to indicate the momentary difference in frequency between the two networks.

7. A device as claimed in claim 4, including a pointer connected with said second contact, a

stationary dial having a scale associated with said pointer to indicate the momentary difference in frequency between the two networks, and another pointer connected with said contact carried by the arm on said shaft, the angular distance between said two pointers indicating the momentary angular phase displacement between the two networks to be connected in parallel.

8. A device as claimed in claim 5, including a control shaft on which said drum is fixedly secured aimulti-step pulley. secure d:'-to saidicon'trol shaft, another pulley onsaid first namedshaft which rotates with aspeed corresponding to the difference in frequency between the two networks, an endless beltconnecting the last named. pulley Withone'step of themulti-step pulleyon the control shaft, abelt passing over another" stepof the-multi s'teppulley; thje ends of said beltf being arranged substantially parallel, and springs attached totheparallel'ends ofsaid' belt and toan anchor 'bar, v so as to retain the belt jtensioned' and resisting-rotative movement. of said pulleys-said contact device being operated by said control shaft which carries a contact element adapted to engage two contacts and close said electric circuit means when the difference in frequency between the two networks is within predetermined limits.

9. A device as claimed in claim 5, includin a control shaft on which said drum is fixedly secured, a multi-step pulley secured to said control shaft, another pulley on said first named shaft which rotates with a speed corresponding to the difference in frequency between the two networks, an endless belt connecting the last named pulley with one step of the multi-step pulley on the control shaft, a belt passing over another step of the multi-step pulley, the ends of said belt being arranged substantially parallel, and springs attached to the parallel ends of said belt and to an anchor bar, so as to retain the belt tensioned and resisting rotative movement of said pulleys, said contact device comprising a contact sector fixedly attached concentrically on said rotatable control shaft, two stationary contact rails arranged concentrically with respect to said contact sector and carrying each an adjustable contact member adapted to engage said contact sector, the adjustment of said contact members along their respective contact rails determining the limits of the difference in frequency between the two networks within which the electric switch is actuated when both said contact members are engaged by said contact sector.

10. A device as claimed in claim 5, including a control shaft on which said drum is fixedly secured, a multi-step pulley secured to said control shaft, another pulley on said first named shaft which rotates with a speed corresponding to the diiference in frequency between the two networks, an endless belt connecting the last named pulley with one step of the multi-step pulley on the control shaft, a belt passing over another step of the multi-step pulley, the ends of said belt being arranged substantially parallel, and springs attached with one end to the parallel ends of said belt and with their other ends to an anchor bar, so as to retain the belt tensioned and resisting rotative movement of said pulleys, said contact device comprising a contact sector fixedly attached to the circumference of another step of said multi-step pulley, two stationary contact rails arranged concentrically with respect to said contact sector and carrying each an adjustable contact member adapted to engage said con-tact sector, the adjustment of said contact members along their respective contact rails determining the limits of the difference in frequency between the two networks within which the electric switch is actuated when both said contact members are engaged by said contact sector, and a pointer on each said contact members and cooperating with a scale on a fixed dial for indicating the adjustment of said contact members.

11. A device as claimed in claim 5, including a control shaft on which said drum is fixedly secured, a multi-step pulley secured to said control shaft, another pulley on said first named shaft which rotates with a speed corresponding to the difierence in frequency between the two networks, an endless belt connecting the last named pulley with one step of said multi-step pulley on the control shaft, a belt passing over another step of the multi-step pulley, the ends of said belt being arranged substantially parallel, and springs attached to the parallel ends of said belt and to an anchor bar, so as to retain the belt tensioned and resisting rotative movement 0! said pulleys, said anchor bar being adjustable in a plane parallel to a plane in which said control shaft is arranged to vary the angular zone of the pulley engaged by said belt, said contact device being operated by said control shaft which carries a contact element adapted to engage two contacts and close said electric circuit means when the difference in frequency between the two 10 networks is within predetermined limits.

ANDREQS GAN'IENBEIN. JosE' JACKLE.

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