US1575876A - thklixt - Google Patents

Description

March 9 1926.

V. E. THELIN AUTOMATIC SUBSTATION Filed June' 25, 1921 5 Sheets-Sheet 2 VICTOR 77/EL/N ENQSQ EMEQQ WE E? 2.35%

RES-30R 1,57 ,816 V. E. THELIN P UTOMATIC SUBSTATION Filed June 25, .1921 S'Sheets-Sheat 5 MarcB 9 1926.,

mnvms F 1% i. E R g March 9 1926.

v. E. TH ELIN AUTOMATIC SUBSTATION Filed June 25, 1921 v5 Sheets-Sheet 5 V/CTOR 6 7715mm Patented Mar. 9, 1926.

UNITED VICTDR E. THELIN, OB CHICAGG, ILEIHQIQ.

AUTOMAIIG STIBSTATIQN.

Application filed. June 25, 1921. Serial No. 480,392.

.To all whom it may concern:

Be it known that I, Vxo'ron E. THELIN, a

citizen of the United States of America, and

a resident of Chicago, county of Cook, and tate of Illinois, have invented certain new and useful Improvements in Automatic Substations, of which the following is a speci automatic with as few parts as the one described herewith.

My invention is especially adapted for use in power and traction systems having substations fed from high tension alternating current transmission lines, and delivering direct current to the distribution system.

Themain objects of my invention are to provide an improved and simplified system of control apparatus adapted to render a substation or its equivalent entirely autos matic; to provide such a system adapted both to start up and shut down a substation without the presence or assitsance of any attendant whatever; to provide-such a system adapted to be responsive to any predetermined governing factor, as for instance a time clock, the line voltage, current load, or any desired combination of these or other factors to also provide in such a system automatic means to insure correct polarity onthesecondary or direct current side of --the rotary converter before it is connected to the distribution system; and to provide and correlate the necessary apparatus, mechanisms and appliances for such a system adapted to effect the control desired, and to provide a better and more eilicient arrangement of apparatus, so as to simplify the Z 0 operation and render same more dependable.

Anillustrative embodiment of this invention is shown in the accompanying drawings, in which- I Figure l is a conventional diagram showmg the sequence of steps in the operation of starting up the substation.

Fig. 2 is a circuit diagram of the substation as a whole.

Fig. 3 is a side elevation of the magneto motor driven polarized relay.

Fig. 4. is an end view of the device, shown in'Fig. 3, as viewed from the right.

Fig. 5 is a plan of said device of Fig. 3.

Fig. 6 is an enlarged end view of the switch elements of said device of Fig. 3.

Fig. 7 is a conventional circuit diagram of said relay.

Fig. 8 is a front elevation of the combination automatic field control and change-over switch.

Fig. 9 is an end view of said changeover switch as viewed from the left of Fig. 8.

Fig. 10 is a cross section on the line i k-B. of Fig. 8.

Fig. 11 is a cross section on the line B B of Fig. 8.

Fig. 12 is a cross section on the line C---C of Fig. 8.

The automatic substation equipment here shown and described in detail, .represents mainly a simplified form of apparatus for automatically controlling the operation of electrical substation machines such as corn verters, motor generators and the like. In designing this equipment, I have endeavored to duplicate, by means of a few reliable pieces of electrical apparatus, the various operations that an attendant ordinarily performs manually in starting up a substation machine, but each individual piece of apparatus is so interlocked with the rest of the apparatus that each operation must have been properly and effectively carried through before the next operation can take place.

. In order to convey. at once a concise idea of the nature and subject matter of my in vention, I will here state that the method of operation for my improved systei briefly described, for starting a rotary co 'rerter, reference being had to the drawing-1 and especially Figure 1, is as follows:

1st. Contact making" time clock 1 operates. 3nd. Master control relay 9 .i in turn,--

Closes starting contactor 3, Will.

starts the rotary converter on lowvoltage on half tap. 7

4th. Magnetomotor driven polarized relay 4: then operates,- p

5th. Closing the combination field control and automatic change-over switch 5, which in turn,-

6th; Opens the starting contactor 3 and closes the runming. contractor 6, to supply full voltage to the converter,---

7th. After which field circuit time limit relay 7 closes, and the 8th. Automatic reclosing circuit breaker 8 closes, picking up the station load.

case it should be desired to control the substation manually from a remote point, a remote control relay 10 is used as shown at the right of the clock on Fig. 2,

- and this relay is connectedto a remote switch 11 which may be mounted in a cen-' tral power station. V

In case the rotary comes up with reversed polarity, the polarized relay 4 shuts the station down and the above described first four steps of the operation are repeated until the rotary comes up positive, after which the regular full sequence of operation is carried through, as will be more fully explained.

The principal parts of the above mentioned apparatus and for which patent protection is especially desired are the magnetomotor driven polarized relay 4 and the,

combination automatic field control and changeover switch 5. The rest of the equipment mentioned, as well as the protective devices, is mainly standard electrical apparatus some parts of which have been slightly altered for various reasons as hereinafter explained.

A detailed description of the different parts of the apparatus shown is now given which parts are described in the numerical order in which they are numbered.

N 0. L 'mztact making time 010070.

N0. 2.-Master control relay.

This is a standard alternating current contactor switch equipped with contact fin- .iers and interlocks and supplies current to t e various operating circuits.

lilo. 3..tarting contactor.

This apparatus is a standard alternating current solenoid operated multi-pole contactor switch and is used to furnish current at a reduced voltage from the power transformer for the purpose of starting the rotary converter.

N o. 4.M'agnet0m0t0r driven polarized relay.

This devicc, .which is a new and specially built piece of apparatus, consists of two principal parts, namely, a, permanent magnet low voltage direct current motor and a sin le pole knife blade, switch mounted on a s aft which operates as a double throw switch, when connected to said, motor, by means of a specially designed centrifugal friction-clutch. The relay motor armature is connectcdcbetween the postive machine lead and ground with the necessary resistance in the circuit. This resistance is so adjusted that the relay motor does not begin to rotate until the direct voltage on the machine (converter) has reached the maximum voltage obtained \vhen'starting up on a reduced A. (l. pressure. Due tothe fact that the relay motor has permanent magnet fields the direction of the rotation of its armature is dependent on the polarity of the rotary converter. \Vhcn' the relay armature clutch takes hold, thus rotatingthe shaft of the oscillating relay switch and thereby op- (lombinatz'on. automatic field control and change ovm smitciu 'This device also is a specially builtpiccc of apparatus. This switch and the polarized relay 4 are the principal parts of the automaticequipmcnt, and are the means that enable the automatic control to operate-with so few parts as it does. This is'primarily reaches the required speed the centrifugal due to the fact that switch .5 is a combination switch that performs various operations and controls several circuits sin'iultaiu'eously, due to the fact that the various parts are all mounted on the same shaft. This device changes the impressed alternating voltage on the rotary from a reduced potential to full potential and simultaneously changes the field from one-tenth to full field. It is also inter-connected with the rest of the station apparatus in such a way that the rotary will not start up again until said switch returns to the initial starting position, and being equipped with an air dash pot there is sufiicient delay in the opening of said switch for all other apparatus inter-connected with same to have returned to its starting Josition, thus insuring a safe starting 0 rotary.

The structural details of this combination switch 5, as well as those of polarized relay the - i-cally and electrically interconnected with, I

4, above referred to, are described farther on where specific reference will bewmade to the drawings.

N 0. (f -Banning coalector. Thisapparatus which applies "full alterhating potential to the rotary is a duplicateof startlng contactor 3 and is both mechanthe latter so that neither can close until the other has opened.

'JVo. 7.-'Field circuit time limit relay.

This device is a standard inverse time limit overload relay which'is inserted in the shunt field circuitto prevent the rotary converter from going in on the direct current bus with a field current below that required I for the safe operation oi-the equipment. N0. 8.-Auto'mate rec losing circuit breaker.

. This apparatus, which is a standard auto matic reclosing circuit breaker, connects the rotary converter to the station direct current bus. In case this breaker opens due to a short circuit or heavy overload on any of the direct current feeders it will close utoinatically again afterv a certain timelimit has elapsed.

N 0. 9.Self-cor1-eetingtime limit relay.

This is a standardtime limit alternating I potential relay. It is used for the purpose of shutting down the rotary in case same does not pick up the station load aftenthe normal time has I elapsed for so domg.

and in this way it is possible'to correct trouble caused bypoor contacts, etc. Hence the name, self-correcting relay.

1V0; 10. -Rem0te. control starting relay; This relay, which is energized with cur- .rent sent from some remote point by means of pilot wires is used for the purpose of either starting or stopping the-rotary at a time other than that at which the clock either starts or stops the rotary. It. is. also used in place of the clock in case the start- 4 ing and stopping of the rotary is to be done from some remote point.

N0. 11. -L0w voltage relay.

This relay, which is connected between the substation feeder bus'and ground, has a pairof'interlocks that are connected in the control circuit running from time clock.

;#1 and masterrelay #2, and its purpose is to preven tthe station from startin up when -the clockoperates, if the potential of the substation feeder bus is above a certain predetermined value. It is'equipped with a time lirnit device to prevent operation on momentary fluctuations of voltage.

The various protective devices will now be described. lhey are numbered consecutively "from 20 up.

This instrument, which is a standard shunted ty e D. C; machine ammeter, is so arrangec that when the current in the machine reaches some predetermined minimum value, the lower end of the pointer of the instrument opens the circn i to the operating coil of auxiliary low currentrelay 20 causing the interlocks oi' the latter rclay to'openiandshut the rotary down, provided time clock #1 has tripped open. Auxiliary low current relay #20 is [we current rela y.

equipped with a time limit device, so as not to 'respond to momentary fluctuations 'in the load. x 7

N0. 2J.See0ndarg control relay.

.2 causing the latter to open whenever .the

coil of theformer is energized. Due to being interconnected with so many devices as just mentioned andbeingso closely related to master control relay 2, I call it the second N0. 22.Reocrae power relay.

This relay, which is an induction watt relay that operates on a reversal of power in the secondary leads of the power transformer is used for the purpose of preventing the rotary from being damaged from over speed in case of failure of the A. C. power supply. Its trip circuit energizes the lifting coil-ofsecondary control relay 21 as already mentioned above.

No. 23.Re'verse phaserelay. This relay is a standard reverse phase relay that operates to shut down the substation in case any of the three phases reverse or open up. This relay will also shut the station down in case abnormally low A. C- voltage should occur.

2V0. QL- Reoerse phase auxiliary velar;

This relay is a regular solenoid type of relay, which used as an "auxiliary relay to reverse phase relay 23.

.' No. 25.--B'earing thermostats.

These thermostats are mounted on the bearings of the rotary converter, and are used to protect same from becoming overheated.

No. 536.Transf0rmer thermostat.

- N0. fl7'.-0verspeed device.

. N 0. $28.0-ll-eirc'zlit breaker trip relay.

This relay is a specially built piece of apparatus, which is used for the purpose of tripping the release catch on the. handle that. controls the opening and closing Oll switch. whenever thermostats 25 and 26, or speed limit device 27 operate. is also interconnected with the oil circuit breaker control handle 29, so that in case the latter opens, the core of relay 28 will drop causing the automatic rel-losing Cll'L'll ll breaker to also open thereby making it impossible "for the rotary converter to speedup, due to being fed with l). C. from the substation bus.

This is a standard control handle for a type K oil circuit breaker, which handle is equipped with an interlock, so that when same opens, it will cause relay .-()z'l circuit breaker control handle.

' e as mentioned above, thereby opening the automatic reclosmg c1rcu1t breaker on gen.-

crater panel.

N0. 3Q."Reoerse current relay. This relay is a standard reverse current I relay, and is adapted to open up the breaker whenever a reversal of current occurs on same.

I N5. 32.--Substeti0 n operating battery.

I This is a standard twenty cell operating storage battery, which is used to furnish power to certain pieces ofapparatus, that would be inoperative in case they were supplied with power from the station bus which would be dead in case the entire D. C. feeder system were shut down.

N0. 33.Aut0matz'e reelosing feeder circuit 1 I breakers.

I These breakers are st-andard'automatic reclosing circuit breakers. They are used on the feeders for the purpose of cutting same 28 to drop,

off in case of trouble of any 'sort. They automatically reclose whenever the trouble has disappeared.

N o. 34.Seetimmlizing relay.

This relay, which is of a simple solenoid type, is used to separate the ground circuit of the operating coil of the automatic reclosing circuit breaker 8 from that of the oil circuit breaker trip relay 28 whenever the overspeed device 27 opens. If this were not provided for there would be a shunt path to ground around the overspeed device 27' by way of the operating coil of the oil circuit breaker trip relay 28 and storage battery 32 which might prevent automatic reclosing circuit breaker 8 from opening.

IV 0. 40.-0urrent transformer.

This is a standard current transformer that is inserted on the low tension side of the power transformer for the purpose of furnishing current to the reverse power relay 0:

' N0. .4.Z.P0tential transformers.

These are two standard 370 to 110 volt transformers that are used for the purpose of furnishing polyphase potential to reverse phase relay In case the power furnished to the high tension line is obtained from the central station by means of transformers that are Y connected with a grounded neutral, it is possible to install a small trans-- structed electric switch 62 mounted on a' shaft 63, which is rotated by said motor by means of said clutch61 Whenever the motor armature reaches a certain predetermined speed.

The main portion shown on the left of Fig. 3 is a standard permanent magnet ball bearing low voltage D. C. motor 4'. Being equipped with permanent magnet fields, its

rotation is entirely dependent on the polarity of the impressed voltage, and in case this polarity is reversed, the motor will revolve in the opposite direction.

The centrifugal clutch 61, mounted directly on the shaft of the motor, includes springs 67 set radially in pairs on' the ends of which are several weights 68, which move further from the axial center, due to can i a i trifugal action, whenever the motor is speeding up. The left hand collar 69 supports one end of springs 67 and is fastened rigidly to the motor shaft by means of pin A. The

right hand collar supports the opposite ends of said springs, and being loose on the shaft moves inward as the weights move outor D and E, depending on the direction of rotation of the armature. t should be noted that the supporting yoke 74 that holds the two springs to which the friction disks 72 are fastened, is pivoted at pin P thus allowing for any small variation in the turning of disc 71.. The yoke support 74 is threaded on to the switch shaft 63 and is held in place by means of a looknut 77, so

till

that the gap between the discs 72 and the disc 7i can be adjusted, and thus allow a greater or less speed in the motor before the clutch takes hold.

The relay switch 62 comprises the shaft 63 which rotates in bearings 78, a block of fibre 79 clampedon this shaft, two pieces of spring bronze on the ends of which are two copper strips F and G. When the shaft is rotated by means of the centrifugal clutch, these strips of copper close the circult across contact fingers B-C or DE, which are mounted on a fibre base, These contact fingers are made up of a thin flexihis piece of spring bronze and a rigid piece of copper, the flexible piece of spring bronze acting as an arcing tip, due to the fact that the movable copper strip touches this first when making contact, and' leaves it last when breaking the contact, thus insuring a clean surface at all times on the' rigid pieces of copper. ,The method of operation is shown by Fig. 6. The copper strips F and (i that make contact across fingers ll and (l or D and E are mounted on apiece of spring bronzc so as to make perfect contact with the rigid copper fingers B and U in case the latter do not line up perfectly. lVhen the speed of the motor is reduced so that the leather discs leave the disc. 71 at the clutch, the weight W restores the switch to the neutral position, as shown on at tached blue print.

The weight "W is used instead of springs for restoring the switch to its neutral position, for it was found by experiments that when using springs the switch blade would rebound sufiiciently to make contacton the opposite clips. This was due to the fact that when the clutch let go the springs were under maximum tension and as the switch reached its neutral position the springs were at aminimum tension and theswitch 18156- fore not only passed the neutral position but at times continuedto move so far as to make contact'on the. lingers on the opposite side or the switch. The use of a weight suspended on the lower end of the switch eliminated the rebound due to the factthat as the switch moves from either side to the neutral position the weight moves downward as well as sideways and when the switch passes the neutral position the weight has to be stopped in its downward movement and started upward against gravity, which prevents the switch from moving very far past center. I The electrical connections of the polarized relay are shown by Fig. 7.

The combination automatic field control and change over switch 5 is a combination of several switches which are mounted on a common base 73 and so arranged and interconnected-as to obtain either simultaneous or interlocked operation of the various circuits and pieces of apparatus that are controlled by this switch as explained in detail later on. The apparatus consists primarily of seven switches or fingers mounted on a' rotary shaft Tel which is rotated by a solehold 75 equipped with an air dash pot 76.

Three of these switches, namely, #1, #5, and #7 are fastened rigidly to said shaft, while switch #4: is free to move a certain distance being controlled by a spring 77. Switches #2, #3, and #6 on the other hand are what might be called quick make and break knife edge switches that'are operated by a piece of fibre mounted on'said shaft.

A more detailed description of the construction, I function and operation of the parts of said switch 5 may be stated as follows:

Switches #1 and #7, which are identical both as to construction and function as well as operation, are each constructed of fibre cut in. the'shape of two spokes and the hub of a wheel as can be seen In Fig. 9. At the outer end or what would correspond to the rim and of each of the spokes, is mounted a flexible carbon and copper make and break contact finger 79 which makes contact with a similarly constructed finger 80 that is mounted on the switchboard. Finger #1 is connected to the ositive end of the shunt field winding an finger #7 is connected to the negative end. The copper and carbon contacts at both ends of the same finger are tied together and to"-a common binding post '81 by means of flexible leads 82.. The stationary copper and car bon switchboard clips that engage the lower clips on fingers #1 and #7 are connected to the station bus through resistance of the required value to give one tenth the normal full strength on the shunt field while the when closing, the carbons make contact first and the fieiiible copper'fingers last and when opening the copper fingers break first and the carbon last causing latter fingers to receive all the arcing, thus insuring a clean contact on the main copper contacts.- The copper fingers also make a wiping contact thereby making sure of greater reliability in operation. Said solenoid 75 is equipped with an air dash ot 76-so as to cause the combination switc 1 to open slowly, thereby dissipating the energy ofthe field in the arc. The insulation of the field is further protected from a break down by finger #5 which acts as a discharge switch for the field as follows. The two leads of the shunt field in addition to being connected to switches #1 and #7 are also connected to the opposite ends of switch #5 and when the switches move from either ,the lower contacts to the upper contacts or vice versa, switch #5 makes contact with two double sets of switchboard clips that are connected to a low resistance thereby causing the field to discharge through this resistance.

Switch #4 is very similar in construction and shape to switches #1. and #7, the

switch while the switch is held tight principal difference being that the latter two 'are' fastened rigidly to the rotating shaft This switch #4' while the former is not. which might becalled a scaling in switch, is so constructed that it will make contact with the clip 86 on the switch board when the shaft has rotated a small portion only of its total travel, and said switch will remain stationary while the shaft completes its travel during which time in P moves upward in the slot in the middle of the a ainst its clipby means of coiled spring 77. when the combination switch opens again the she it rotates in the opposite direction and when the piniP reaches the bottom of the slot in the finger switch #4 will open again against the action of the spring77.

Switches #2 #3 and #6 are quick acting knife edge make and break switches which are especially designed so ,as to provide. a certain time delay during which other switches on the same shaft make vor break their circuit and when the former finally operate they do so with out a seconds delay in their action. Switches #2 and #3 are constructed as follows: A piece of fiber 88 cut in the shape of capltal letter H is edge of a V-shaped metal groove 90 while the two upperarms of the H are equipped vith-copper fingers 91 that rest against'two independent copper clips92 when the switch is in the open position and make contact with two other independent clips on the switchboard when the switch is in the closed position. 'The switches are held tight against the forward stops or clips by means 0 a coiled spring 93 which is fastened between the center part of the H switch Zr-3 and the top of a short fibre finger that is fastened rigidly to the rotating shaft. When the shaft revolves or rotates the top of the.

fibre finger-moves nearer and nearer the kmfe edges on the H switch and the tension on the spring becomes less and less and when the finger has passed to a point to the other sideof a line drawn through the center of the revolving shaft and the knife edges, the H switch snaps over to the other position quickly and as the top of the fiber finger moves more and more toward the switchboard, the tension on the spring becomes greater thus insuring a perfect contact between the various electrical parts. en

the combination switch opens again the op.- eration is just the reverse of that mentioned above. f

Switch #6 is, also a quick break knife edge switch but difiersfrom #2 and -#3 in that it is a single pole switch whereas the combination of #2 and #3 form a double pole switch. Switch 6 is nipped with an air bellows time limit device 95 which further increases the time of operation of the switch as follows: The fibre finger on this switch is constructed like that on switch -t in that it is not fastened'rigidly to the s aft but is controlled by a spring 96 that is coiled around and fastened to the shaft.

When the shaft rotates the tension in the whighis the last The time limit deviceis in operaprevents the burning of the copper fingers. The copper part ofthe finger is made up of two parts, namely. the secondary break 98 and the main finger 99, the latter of which is designed to carry the current. In case,-

the carbon tips just mentioned above should fail to function properly the arc would be broken on the secondary break and still.

leave the main contact linger in good condition foncarryin'gthe current. \Vhere' the current is not very great the carbon arcing tip' is not needed.

Operation of flufom'nfirr equipment.

The position of tho-various partsol' the automatic equipment in case there is no trouble existing on the A. t. high tension line when the-station is really to start up is as follows:

The oil ircuit breaker 29. thetrip. relay 2%, the A. operating bus switch 5] and the (l.'operating bus switch 52 are closed, and change over switches 56, 57 and 58 are in the downward position. The circuit for relay 2 is as follows: from storage battery operating bus S through S relay 28, N, lower right blade of change over switch 58, N interlock. onoil circuit breaker handle 29, N 7, contacts of sectionalizing relay 34, N N coil of sectionalizing relay 34, N transformer thermostat 26, N bearing thermostat- 25, N bearing thermostat 25, N speed limit 27 and N to negative ope crating bus. Time clock 1, master control relay 2, starting contactor 3, running contacton 6 and automatic reclosing circuit breaker S are open, but main D. C. switch in rotary positive lead is closed and various protective devices are either open or in a neutral position, The polarized relay 4: 1s

in the neutral position.andcombination automatic change over switch 5 is'in the open or starting position. The shunt field of there- "tary is excited with current from the station crating bus.

bus which current is approximately amp. or one-tenthof the normal exciting current. The circuit to the shunt field S. F. is as follows: from the substation main positive bus through P left hand lower blade of switch 56, P ,.o ne-tenth lield resistance, P lower half of finger B of combination switch 5,

middle blade, lower middle clip, jumper and upper right hand clip of change over switch 57, P upper-left hand clip of shunt field break up switch. Then through shunt filed to N, lower left' hand clip of change over switch 57, N lower half of finger A and lower left hand clip of combination change over switch 5 and N? to negativeopv Starting. I v When contact making time clock l' operates. a circuit is completed to .master cont-rol relay 2 from A phase-operating bug-At, middle lower clip; of changer over switch 58, upper part of time clock switch, lower left hand clip of change over switch 58,..A interlock on secondary control relay2l, A A, quick break finger G of combination iautomatic switch 5, A5, A, upper interlock of reverse phase auxiliary relay 24, A master control relay resistance 2', operating coil of master control relay 2, B B to B phase operating bus.

In case the rotary to be started by meanso-l remote control instead of by means of clock 1 the circuits are completed through the interlocks of remote control relay 10 in.- stcad of through the interlock of clock 1.

\l'hen master control relay 2 closes, a circuit is made to starting contactor u as follows: from it phaseoperating bus through H. l)". lingcr 2 of master control rclay2, B", quich break linger F of combination automatic change over switch 5, operatin; coil of starting contactor 3. C, C and C to C phase operating bus. The closing of starting contactor 3 connects the rotary to p the half tap of the power transformer (185 to the armature of magnetometer driven polarized relay 4 as follows: from positive operating bus 1 through i, armature of polarized relay 4 and resistance 4', N lower interlocks on starting cont-actor 3 and N to negative operating bus N. time that the rotary starts up there is A. C. potential generated across the D. C. leads of the machine and as the speed becomes greater the frequency of this A. C. current decreases until finally the rotary locks into step with the frequency of the A. C. high tension supply line and the rot-aryassumes a. definite polarity butin this case due to the fact that tl'ielield is excited from an independent ex- During the ternal source of power, namely, the station D. C. positive bus, the rotary comes up with the correct polarity, that is to say, the lead going to the'station bus being positive.

lVhcn the rotary first starts the high frequency current has no effect on the motor of polarized relayiibut as thefrequency with correct'polarity it will rotate in the.

eorrectdirection and continue the sequence of operation. ,1; resistance is inserted in X series witl-rfthe armature so': that it will not start to rotate until the voltage is somewhere near the-full value to' bereached while r0 tary is running on the half tap of thetrans; former. When polarized relay operates in.

the positive direction itmakes a circuit across positive clips D and E to the o crab ing coil of combination automatic fiel control and change over switch 5 as follows: from positive operating bus P'through P 1: to positive clip D. finger G to positive clip E, P too'perating, coilof combination change over switch 5, N, N, finger Eof switch 5, N" to finger, 5 of master control relay 2 and then through N to negative operating bus N. When combination change over switch 5 closes, there are many changes that take place, but those things which have to do with completing the operation of the switch itself will be described first. v As already explained under the detailed description of the construction of this switch finger D is operated by means of a spring when closing and after having made contact with its clip on the'switchboard, the shaft continues to rotate due to the fact that the finger is loose on the shaft. When the switch in the open position there is very little space between finger D, and the cli on the switchboard and contact is made he ore the shaft has moved very far, and before any of the other fingers or switches have operated. Finger D just mentioned is a holding in or scaling in finger and it together with wire P forms a shunt circuit around contact clips D and E of polarized relay 4 when the latter opens as explained later on. In order that the coil of combination change over switch 5 will have plenty of power when closing the switch, the resistance 5 in series with the coil is'shunf ted by quick break switch E. This latter switch is e uiplpedwith an air bellows time limit vs ic prevents the short circuit from being removed from around the resistance until the core of the solenoid coi'l will have comleted its travel and sealed in perfectly. ue to being equipped witha time limit,

' finger E is the last switcher finger on combination switch 5 to operate. When combination switch 5 moves from the open to the closed position, fingers A and Bbreak the one-tenth field circuit on the lower clips and transfer the field, to full voltage as follows: from rotary positive i leadf through P to field rheostatAA, P", right blade of change over switch 57 to bottom right hand clip of same, P to coil of-field cir cuit time limit relay 7, P upper right hand clip and finger B of combination switch 5, P middle blade, lower clip,

time that combination switch 5 moves from the open, to the closed position contact is made by finger C with its clips-thus connecting the two ends of the shunt field across a -low resistance and discharging the field.

As a precaution against a high induced voltage in" case .an open circuit. should developin the wiring of the one-tenth ficld circuita resistance of approximately 750 ohms is connected directly across the exupper right clip of change 5 'statiom- Iffswitch 5 were in the clos treme lower left and'right hand clips of combination switch 5 and when fingersA and B are in the down position the resistance is actually tied across the field itself.

.The only switches or fingers on combination construction details, these two switches control independent, circuits but are mechanas yet, are F and'G, and

ically fastened together in order to get si-.

multaneous operation.

the station'bus to the lead of the rotary and so made it self-excited, switch F operates and changes the rotary from the half tap \Vhen switches A- and B have transferred the shunt field from to the full tap by opening starting contactor 3 and closing running contactor 6, and the circuit for making this change is as follows: from B phase operating bus through B B, finger 2 of master control .relay, B, finger F of combination switch 5, B operating coil of running contactor 6, C", upper interlocks of starting contactor 3, C and C to C phase operating bus. When starting contactor 3 opens, its lowerinterlocks open the circuit between N and N which shuts down polarized relay 4, as its services are no longer needed. It should be noted that the circuit that controls the operation of.

running contactor 6 as just mentioned above,

is so interlocked .with starting contactor 3 that the latter has to be open before the former can be closed and the circuit for opcrating running contactor 6, therefore-,-is Y not completed when finger F ofcombination switch 5 operates until contactor 3 opens.

In addition to being electrically interlocked,

starting contactor 3 and runmng contactor 6 are also mechanicall interlocked so it is impossible to close 0th simultaneously, which wouldresult in a short circuit between the half tap and the full tap on the transformer in case same did happen. Finger G of combination switch 5, w is in parallel with finger 4 of master control relay 2, is installed as a safety interlock in theoperatin coil circuit of master control relay 2 so t at the lattercan not close again at any time until combination change over switch 5 has returned to the ich finger open. position and has thereby restored all of the automatic equiplmentto the normal position for starting t e station a ain. If thisinterlock were not provide master control'relay would close as soonas secondary control relay 21 dropped regardless as to whether combination change over switch were still in the closed position, or the open or normal position for startin the sition when master control relay 2 closed again the rotary would be connected across the fullpotential of the transformers with relay 2 closed l'lri noted in early part of this report under description of operation. 'lhedeta ls ol' the operation of the various parts of ombination switch 5 are now complete and' the rotary is gnow running at nor mal speed with full potential of the correct polarity and ready to pick up thestation load. As already noted, the circuit from linger B of switch 5 tothe shunt field passed through the operating coil of field circuit time limit relay 7 and if the current in the field is up to the required. yalue'the relay will close its contacts after a'certain. time has elapsed, which time limit is provided to enable the rotary to build up to its full potential. W'hen relay 7 closes its contacts, a circuit'is made to generator breaker S, which is an' automatic reclosing circuit breaker, as follows: from positive lead of rotary converter through 1?, interlocks of reverse current relay 30, P operating coil of circuit breaker 8, N middle blade and lower middle clip of change over switch 56, N, contact clips of field circuit time limit relay 7, N finger 3 of master control relay 2, N interlocks on running contactor 6,

N and 18, contact clips of oil circuit breaker trip relay 28, N time clock 1, N

N coil of sectionalizing relay 34 and so on through thermostats and speed l m t to negative operatingbus. The closing of the breaker completes-the cycle of operation of starting the rotary and picking up the station load, which operation is completed in approximately 40-50 seconds.

There is one finger or switch blade on master control relay-2, of which no mention has been made as yet in connection with'the starting of the station, and that is finger l which controls the operation of self-correcting time limit relay 9. \Vhile this piece-of apparatus is a protective device in that it has to dodirectly with the starting up of the station, or rather the failure of? the station in starting, and, therefore, it no doubt would be bcstto describe the operation of same-at this time. This relay which has a time limit that can be set-from a few so"- onds to several minutes is so connected that in case generator breaker 8 did not close inside of the setting of the time limit of selfcorrecting relay 9 the contacts of the, latter relaywould close, therebycompleting cuit to secondary control relay"; would cause master control relay This in turn would open runinhi U which would cut off the All the rotary causing same to gradually shut down. Combination switch 5, being connected directly across the iiositive operating bus through holding linger l), w cli circuit is not interlocked throughginaster control relay :2 in any way, would stay closed until the voltage on operating bus I. dropped to a alue below that at which the operating coil of combination switch will stay closed after which same will open up and thereby close circuit to operating coil of master control relay 2 through finger (l of switch 5. The regular sequence of operation of starting the. rotary, as already explained in detail, would then be carried through again and the trouble that prevented the operation from being completed before (which might have been caused by poor contact, sticking of relay, etc;) might be overcome and the rotary would then pick up the load in say 40 15 seconds. In case the trouble were not remedied the first time, relay 9 would shut the station down again and continue to do so until the trouble were remedied if same could be remedied, It is a well-known fact that no matter. what piece of apparatus man makes, that out of say a-few thousand operations, there will be some hitch somewhere that will result in a certain-percentage of failure which fact does not mean, however. that the apparatus will not work at all. In the automatic substation apparatus shown in the drawings, each operation of the apparatus is so interlocked that the failure of any part of same to function properly will prevent the sequence of oper tion to he carried further and in case of trouble onany part of same, the sequence of operation would be carried through to this point and no further. It the trouble, however, is a temporary one, such as poor contact, sticking of some part of the apparatus, etc, the addition of relay .-9 to the automatic equipment gives same a chance to start over again and possibly overcome this trouble. If for some" reason the rotary came up with its polarity reversed, the

armature ofpolarized relay at will rotate in' and inasmuch as the rotary is generating" half voltage, i. ve., 300 volt, a section only of resistance 21 is used by making a tap connection as above-mentioned, and positive operation o't relay 21 is thus assured. \Vhen relay 21 operates it opens the circuit to the motor of polarized relay & thcrefore would I- slow down. This would in turn open the circuit across negative clips and C of polarized relay 4, and secondary control relay 21 would drop again, thereby closing the circuit to master control relay 2, which a pole as it is called.

contactor 3, and rotary again to the half tap of All of the operations would close starting would be connected the transformer.

would require a few seconds of time only,

and the polarity of the rotary would not be corrected, as the rotary would not have sufiicient time to drop out of step and slip This trouble is overcome, however, as follows: \Vhen core of secondary control relay. 21 is lifted a contact is made across two fingers in the relay, thereby completing a sealing in circuit as follows: from positive? operating bus P through 1?, holding in fingers of relay 21, P, resistance 21", operating coil of relay 21 and N to negative operating bus. The coil of relay 21 is tllel'lj connected directly across the rotary armature, and its core will stay up until the rotary has slowed down so that the voltage is not; more than 25-50 volts. This allows sufficient time for the field to die down and when the rotary starts up again it will have a'fair chance to cor- ,rectits polarity. The performance outlined abovewill continue to take place until the rotary comes up withthe correct polarity,

' at which time polarized relay 4 will rotate A in the positive direction.

The fact that polarized relay 4 definitely determines whether the conditionsgon the rotary are such for the balance of the operations to be carried through successfully, and not, to bring about operationfon various pieces of apparatus for corr'ecting the fault, makes this piece of apparatus one of the most i'm portant in the whole equipment.

Shutting down the station.

After automatic reclosing circuit breaker 8 closed and picked up-the station load, the position of the various parts of apparatus the trip coil 28 are closed, the latter being energized from the battery as explained.

Operating bus switches 51 -and 52, and change over switches 56,- 57, and 58, "are closed in the down position, time switch 1 is closed,.master relay 2 is closed, starting con tactor 3 is open, running contactor 6 is relay 4 is rent relay 20 and secondary control relay 21 are in the neutral position, as shownon print. Speed limit device 27, bearing'ther-' mostats 25, transformer thermostat 26 and sectionalizing relay 34 are in ,their closed position. Relay 9 is in the open position.

The station is, therefore, "ready to shut down normally as follows: Time clock 1 is set beforehand to open at some certain time, and when the time arrives, the circuit between the operating coil of circuit breaker 8 and ground is broken between N and N and the breaker opens dropping the station load. The connection between A and A in the A. C. feed to master relay 2 is also opened ,when the clock operated, but it should be noted that the gap is shunted by lay 2*, reverse power relay 22,. reverse curthe rear interlock on circuit breaker 8 and wires A? and A, and relay 2, Will not open until circuit breaker 8 has opened. This is done for two reasons, namely, to keep the rotary supplied with power fromthe 'A. C. side until the D. power is cut off, thereby making it impossible for the rotary to run away, and also to drop the station load on the l). ning eontactor 6, as the carbon arcing tips on the former-"arein better position to take the arc than the copper fingers of the latter. \Vhen circuit breaker 8 opens in normal-operation of the station, due to heavy overload,- master relay 2 is prevented from opening due to the interlock on breaker being shunted by upper switch in time clock. When master relay 2 opens, its fingers open circuits to various apparatus as follows: fingers 2 openedthe control circuit to operat- .ing coil of running contactor 6, causing same down. Finger 3 opened the ground circuit- ,to automatic reclosing circuit breaker 8, vwhich circuit has already been lnterrupted in the time clock, and which is also interrupted'when interlock on running contactor 6 opens. Finger 4 of master relay 2 places another open circuit in the control circuit to operating coil of master relay 2, which open cimuitis bridged when finger G of combination switch 5 moves'back when latter switch opens, thereby insuring that switch 5 is in its. normal starting "position before master relay 2 can-close again. Inasmuch as the operating coil of automatic change over switch 5 is supplied with power from the positive operating bus P through self-holding, in finger D the switch will stay closed un ti1=the rotary has slowed 'down tothe point. where there is not-sirflicientpower to C. breaker instead of on the A. 0. runstarting contactor 3.

opens ahead of finger l), and it is evident that if no other open circuit were provided in this shunt circuit that switch 5 would immediately close again due to its resistance being cut out. Finger B would then open again causing switch to open again, and the switch would continue to open .and close until the voltage of the rotary had decreased to a point where the switch would not have sufficient power toeoperate, even though the resistance were cutout. This condition is remedied, however, by finger 5 ofanaster relay 2, which keeps the shunt circuit around resistance 5" open until master relay 2 closes in its regular sequence of operation. The openingof combination switch 5, transfers the shunt field from full strength supplied by the rotary itself to one-tenth full field supplied by the statiol'r bus. The fact that combination change over switch 5 stays closed till the rotary has slowed down, reduces the strength of the fieldconsiderably, and what little fiuxis left is dissipated through the field discharge resistance through finger G, as fingers A and B moved from the upper to the lower contact clips. Thesafe discharge of the shunt field is further guaranteed by the addition of time limit to the core of the operating coil of combination switch 5, which causes the latter to open very slowly. This will prevent the field from discharging very quickly in case switch 5 should open while rotary was in full service'and having full strength field "current. Relay 7 also dropped as the field was discharged. Nhen switch 5 opened, finger F opened, thereby transferringthe A. C. control circuit from running contactor 6 to shut down, all different parts of the apparatus are in their position for starting the rotary again. In case it is desired to have the rotary continue in operation after the time at which the clock operates, remote control relay 10 is closed before the clock has operated and is kept closed until the rotary is to be shut down, the circuits being kept closed by means of the interlocks of the remote control relay, which interlocks are connlectled in parallel with the interlocks on the c oc r.

The station is now In case the station is controlled en I tirely by meansof the remote control relay the rotary will of course be shut down by means of this relay. In allot the above mentioned methods for shutting down the. rotary. in case it is desired to continue the rotary in operation if the load carried by same is very great, low current relay 20' will prevent the rotary from shutting down, as its interlocks shunt the interlocks on time clock #1 amlremotc control relay #10:-

Funclion and operation.- of f/l various pro zr -iice devices in (use of trouble.

1 will'now describe in detail the theory and operation of the various protective devices in handling any trouble that might occur either inside or outside of the station.

1 have already briefly described these de-.

vices in a general way, but. certain specific features should also be ulnlerstood, as follows:

Machine b/eu/rcrs, (SC-This breaker, which is an automatic .reclosing circuit breaker, di ffers from the feeder circuit breakers 31, in that, in case the former opens at the same time as any of the feeder breakers, due, for instance, to a very severe short circuit it -will reclose again after itstilne limit switch has closed. regardless of conditions on the feeder, whereas the feeder breakers stay open until the trouble on the feeder has been cleared up. If, however, there is one feeder only in the station it would only be necessary to use one feeder type of circuit breaker which would act both as generator breaker and feeder breaker. NVhen main breaker 8 opens, its front interlocks close the circuit to the operating coil of self-correcting relay J, and if the breaker has opened dueto orerhiad it will reclose again in a few seconds, and relay 9 will drop down again. If, however, the breaker opened due to some trouble in the control wiring. of the breaker, such as poor contact on one of the various inter- Self-correcting relay 9.This device makes'it possible for the automatic equipp,

ment to start over again in its cycle of operation in case any trouble develops. Hence, it is possible for the equipment in some cases to remedy the trouble, which feature is characterized by the name self-correcting relay. Low current relay Q0.'-This instrument is a regular shunted type switchboard ain- -respond to momentary fluctuations in ourthe, lower end of. the pointer and the platinum 3 tip is broken, causing low current auxiliary 20 to drop its plunger and open tlnshunt circuit around; the interlocks time-clock #1 and remote control-relay 10. Low current. auxiliary relay 20 equipped with a time limit, so as not to ,rent. I

Secondary control relay 21.-'This relay is simply a solenoid type of relay which is used as an auxiliary-relay for practically everyprotective device in the station. It controls the opening of master control relay 2, hence,

I call it the secondary control relay. Its

' main use in the station is to act as an aux;

iliary relay to carry the heavy currents which would in time burnthe delicate c011 tacts in the tripping circuits of the various" protectivedevices and so cause trouble. This. is accomplished in a two fold way, first due to the fact that the operating coil of relay 21 is wound with a great number of turns of fine wire, and, therefore, cutsdown the amount of current that is carried by the contacts in the various protective devices,

and second due to the fact that this relay is equipped with a set of self-holding interlocks that form a shunt path around all the deliafter which therelay holds itself closed and cate cont-acts in the tripping circuits of the various protective devices, it is only neces sary for these contacts to make the circuit,

the various protective devices can return to their normal position without being called to break the circuit to secondary control relay, 21, which fact eliminates all .burning of the contacts The fact that secondary control rel'av stays closed till the rotary has practically ceased to rotate or generate, any

current materially assists in keeping other parts of the apparatus in good operating con- 'dition'when they are called upon to open the circuits,-such as field control, various contact clips, reversal of field in case of wrongpolarity, -etc. some of wliich'points have already been touched upon in preceding parts of the report. v j" Reverse power relay 22.This meter, which is a standard single phase induction wattmeter,'has its current coils connected in one phase of the low tension power circuit by and its potential coils across this one phase and each of the other phases. When the machine is running, in normal service the disc of this meter tends to move, but is prevented i in so doing by a small stop which holds the contacts of the trip circuit open about 3 2' of an inch. In case the A. G. power supply to the rotary Were interru ted the machine would run as an inverte rotary supplying at least exciting current to the power transformer. The otential would still he the same, but the irection of the current "would be reversed,- which would cause the disc -'contacts on the trip circuit in the relafyg, causing secondary control relay-21-to 'li which in turn would open up master control relay 2, causing rotary to shut down. The

fact that the gap in the trip circuit in the reverse power relay is small, makes the meter operate very quickly (approximately one second) and in case the A. 0. power is re-' stored very quickly in case of high tension trouble, it prevents the rotary from getting a sevee jolt which would result due to the A. C. power on the line being out of phase with the power being generated by the rotary when the latter is running as a generator with full strength field. i 1

Reverse phase relay 23.This relay as already mentioned is a standard three phase reverse phase relay that has an aluminum disc that is caused to rotate by a rotating magnetic field... The meter is connected to a two 37 0/ volt potential transformers thatare connected open delta across, thenthree phases of the secondary leads of the power transformers. In normal services the disc of the meter is rotated to the left as shown in, the drawing until contactis made with a connection that short circuits the coil and resistance of auxiliary relay 24. In case of loss'ofany'of the three phases, the electrical torque thatrotated the disc disappears and-a coiled hair spring on the shaft of the meter causes the disc to rotate'to the riglit and make contact with thejright hand term nal'inthe meter, thereby completing a circuit" to thefoperating coil of auxiliary relay 24, causing same to lift and open the circuit to master control relay 2," thereby.

shutting down the'rotary. "Relay 24: is simply'a straight A. C. solenoid typebf relay that is equipped with two interlocks, upper one of which is used to control the circuit 'to master-control, relay 2, and the lower one serving as a self-holding or shunt circuit for the right hand contactin'reverse phase relay 23 in order to hold auxiliary relay 24;

up until conditions are restored to normal. 4

.flhe controll'circui't for auxiliary relay 24;

conditions are restored to normal, the disc of reverse phase relaymoves to the left, again engaging the left hand contact .stud and short circuitmg the coil and resistance 1/. of auxiliary relay 24, causing same to drop,

which closes the circuit to master control relay 2, causing the rotary to start up again.

In case of loss of any of the phases the coiled spring alone causes the disc to rotate. to the right, but in case any of the phases become ieversed it would not be necessary to have a spring on the shaft because the reversed phase will cause the rotating magnetic field to reverse, which of itself would be suflicicnt to cause the disc to reverse from its normal direction of travel. not take care of a reversal of power because its operation is like that of a motor which will reverse'if we reverse either the field or the armature, but which will run in the same direction if both are reversed. A reversal of power is taken care of by reverse power relay 22 already described above. Reverse phase relay 23 will also shut the sta ion down if the A. 0. power becomes so low that.

the torque of the meter is not sufficient to overcome the pull on the coiled spring. In case any of the above-mentioned troubles occur while the rotary is not running. reverse phase relay 23 will keep same from starting up until the trouble has been cleared. y

Bearing thermostats 25.These thermostats are put in the bearing for the purpose of shutting down the rotary from both the A. C. and D. C. sources of power, in case the bearings become overheated. The electrical. part'of the thermostats is connected in the common lead that runs from oil circuit strip relay 28 and the operating coil of auto, matic reclosing' circuit breaker 8, and when the thremostat operates this common circuit is broken and the core in relay 28 drops on the release latch on oil circuit breaker operating handle, causing the oil circuit breaker to open and cut off the A. C. source of supply. The circuit to the operating coil of automatic circuit breaker 8 is also broken at this time and the breaker opens shutting off the D. C. source of supply, thereby cans-- ing the rotary to shut down. 'Whcn the sta tion is shut down by the thermostat it is necessaryto close the oil switch by hand again before the station can be started automati ally. The oil sw tch could he arranged to reclose automatically, but if the This meter will station were shutdown due to an overheated bearing, same should at least be inspected before the station is put back in service.

Transformer thermostats 26.This thermostat, v hich is a duplicate of the ones described above, both as toconstruction and operation, shuts down the rotary in case the transformer becomes overheated. ()rerspeed device 27.This device, which is made in the form of a centrifugal switch, is mounted on the end of the armature shaft to prevent the rotary from being damaged due to overspeed. The electrical switch part of the speed limit device is in the same circuit with the thermostats just mentioned above, and when the weights open up due to centrifugal force, the same circuits described above open up thereby shutting down the rotary. operated it is necessary to reset same by hand before station can be started automatic again. In the automatic substation, however, this device is added to the rotary as an extra. precaution, as the various cases of trouble that would cause the rotary to run away are provided against by means of the protective devices already described in preceding parts of this report, which devices should immediately shut down the rotary before same has a chance to speed up. Botlrreversecurrent relay 20 and reverse power relay 22 would have to be outthe above trouble had taken place. The oil After the speed limit device has" circuit breaker handle is also equipped with toggle tripping device that is operated by means of an overload timelimit relay whenever an excessive overload occurs on the A. C. sideof the rotary, in which case it is also necessary to close the oil switch by hand before the station can be startedagain automatically. Excessive overloads on the/D. C.

feeders are taken careof by the feeder circuit breakers which are set to .open 1nstantaneously,,whereas the A. C. relay just mentioned has a time limit which would only be called on to operate in case of burnout on the machine itself, or in case all of the feeders. become overloaded simultaneously, which is very rare,

Reverse current relay 30 on, main brcake1'.- This relay which is mounted on the main stud of the automatic reclosing circuit rotary and ground.

breaker 8 is equipped with a movable contact that is in the operating circuit of automatic reclosing circuit breaker 8. The coil that closes the contact finger is connected between the main positive cable of the \Vhen field circuit time limit relay 7 is not energized. it

shunts a portion of the resistance that isin series with the reverse current relay coil which causes the latter relay to close. and when field circuit relay -'T operates. it removes the shunt around a portion of the resistance and the current flowing in the coil of the relay is barely sufficient to keep its contact closed. \Yhen the current in the main circuit ofthe circuit breaker h resummary of the various causes of trouble that might arise in connection with the operation of an automatic substation and also shows the different protective 'devices that will function in each instance.

1st. One phase of A. C. supply line being opened during time of normal shutdown: apparatus functioning if machine attempts to start up is reverse phase relay 23, which opens auxiliary relay 24, which in turn prevents master relay 2 from closing.

2nd. One phase of A. C. supply line being opened duringv time machine is running, the following apparatus functioning:

reverse phase relay 23 which opens auxiliary relay 24, which in turn opens master relay 2.

3rd. Phase rotation of A. C. supply becoming reversed either while machine is running or during time of shutdown, the following apparatus functioning: phase relay 23, opening auxiliary relay 24. which in turn opens master control relay 2 if machine -is in operation, or prevents same from closing if machine was not in operation.

4th. Abnormally low voltage on A. C. supply either while machine is running or during time that station is shut downQthe following apparatus functioning: "reverse phase relay 23, opening auxiliary relay 24-. which in turn opens master control relay 2 if machine is i operation, or prevents same,

from closing i machine was, not in opera tion. I

reverse 5th. A. 0. supply being momentarily interrupted while machine is running carrying l). C. load, the following apparatus functioning: reverse current relay 20 and reverse power relay 2:2. operating secondary control relay 21. which in turn open master control relay 2.

(lth. A. C. supply being momentarily interrupted while machine is running. but before I C. machine breaker R has closed, the following apparatus functioning: reverse power relay 22; operating secondary control relay :21. which in turn opens master control relay 2.

7th. C. supply being interrupted during time of shutdown. apparatus functioning: Due to lack of 3 phase pressure. reverse phase relay 23 will open auxiliary relay 24, which in turn will prevent relay 2 from closing. These relays will remain .open until 3 phase power of correct phase rotation and potential is again available on the high tension line.

8th. D. C. overload on rotary converter,

apparatus functioning: I). C. automatic circuit breaker 8 and D. C. automatic feeder circuit breakers 9th. Rotary converter attempting to run at dangerous speed. apparatus functioning: Speed limit relay 2?. opening sectionalizing' relay 34. oil switch 29. relay 28 and D. C. fo tary circuit breaker 8.

10th. Rotary converter attempting to build up and pick up D. C. load while polarity is reversed. apparatus functioning: Polarized relay 4. operating secondary control relay 21. which in turn opens master control relay 2.

11th. Reversal of polarity of rotary while. carrying. D. C. load due to disturbance of A. C. supply. apparatus functioning: Reverse current relay 20. operating secondary control relay 21, which in turn opens master control relay 2.

12th. Dirt and dust accumulating in any of the contacts of apparatus causing same to fail to make proper contacts. apparatus functioning: Relay 9. operating secondary control relay 21, which in turn opens master cont-r01 relay 2.

13th. Momentary interruptionof A. C. su ply while machine is running from A. C. side, but before I). C. circuit breaker R has closed, the following apparatus function-' ing: Reverse power relay 2:2. operating secondary control relay 21. which in time opens master. control relay 2.

14th. Temperature of power transformer rising above safe value, apparatus functioning: 'lransformer thermostat opening sectionalizing relay 34, oil switch 29, relay 28 and D. C. circuit breaker 8.,

15th Rotary converter bearings rising to an abnormal temperature, following apparaing apparatus functioning: Overload relay.

on switch 29, o'ienin switch 29 which in turn' opens relay 2S and 1). C. circuit breaker S.

17th. ()pen circuitin shunt eld. following apparatus functioning: Shunt field relay T and 1). C. circuit breaker 8.

Semi-automatic operationof Me substation.

In case any of the automatic control apparatus should get out of order tosuch an extent as to make immediate repairs 1mpossible, the apparatus has been so arranged by means of throw over-switches, etc, as to enable an inspector to start the rotary and let it run by itself until shut down by means of a clock or remote control relay, and at' the same time be protected with various devices that would .prevent the equipment from being damaged in case of trouble. This is accomplished as follows: Change over switches'fifi, 57 and 58 are thrown upward, thereby cutting in that portion of the automatic equipment that is to be for manual operation. and A. operating bus switch 51 and I). C. operating bus switch 52 are opened, thereby shutting off the power, both A. and l). G. from that portion of the apparatusthat is not to be used in the manual operation of the station. Shunt l'ield'break up switch (51 is also opened.

The method of operation is then as follows: Contact making time clock 1. or remotecontrol relay 10, and oil circuit. breaker handle 29 are closed and the cores in oil circuit breaker trip relay 28 and sectionalizing relay 34 are lifted. Hand-operated starting switch (it) is thrown to the. "half tap position and the rotary starts up and falls into step with the frequency on the high tension line. If the rotary should come up'with the wrong polarity, the oil switch is opened and the rotary .is allowed to slow'down after which the oil switch is closed again, thereby causing the rotary to slip a pole and correct its polarity. \Vhen the polarity has come iipfli 'i'ect, field break up switch 61 is closed, and hand operated starting switch 00 is thrown to the full volt.- age or running position. The rotaryisnow up to full voltage and correct polarity, andby closing a small control switch, automatic reclosing circuit breaker 8 is made to close thereby picking up the station load The station is now in regular service and if no trouble occurs, it will continue until shut down by means of time clock or remote control relay. The rotary is protected against various ,trouble as follows:

(i) Overload on 1). (J. feeders by means of automatic reclosing circuit breakers 33 on feeders.

('2) ()verheated bearings by means of thermostats 25. (3) ()verheated transformer by means of thermostat 26.

(-1) Reverse current by means of.re verse current relay 30. (5) Qrerspeed vice 2T (6) D. C. overloadon rotary bymeansof automatic reclosing circuit breaker 8.

(7) Extreme A. C-. overload by means of overload time limit relays.

From the foregoing. it may be seen that the apparatus described is .a simplified form of equipment for the automatic starting, running and shutting down of light, power and railway substations. It will be observed that with this apparatus, I duplicate the simple operations that a substation attendant would perform when starting up the station. and yet I have the apparatus so arranm'dthat each operation will have been carried through successfully beforethe by means of overspeed denext one can take place, and also I have the than a manually operated substation. The

similarity between manual operation and automatic operation is as follows, The contact making time'clock 1 is set to start the station at some. predetermined time, and when it operates, theuthe master control relay closes the switch that starts the ro-- tary. This switching is done on the low tension side of the transformer instead of on the high tension side as is the case with a manually operated station. When the ro-' tary comes up to synchronous speed, polar-J izcd relay it determines whether the polarity is correct or incorrect, and it the latter is the case it takes the necessary steps to correct. same. which corresponds to the operator correcting the polarity by using field. break up switch (51. \Vhen the polarity is correct polarized relay 4 closes the combinatien switch 5, which in turn connects-the held to the rotary lead and also changes the rotary from the half tap to the full tap on the transformer. This, in the case of a manually operated substation is done by throwing hand operated switch 60 from the starting position to the running position. In ,the automatic substation the field rheostatis set beforehand to give a certain voltage on the machine, and if the field has .come

up to the proper value for thesafe o era tion of the rotary field circuit, time imit to automatic reclosing circuit breaker .8,

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