US1942789A - Apparatus for paralleling synchronous machines to maintain reciprocating engines or pumps in synchronism - Google Patents

Description

Jan. 9, 1,934. w, WlLSQN E1- AL 1,942,789

APPARATUS FOR PARALLELING SYNGHRONOUS MACHINES TO MAINTAIN RECIPROCATING ENGINES OR PUMPS IN SYNCHRONISM Filed Jan. 14. 1952 ,2 Sheets-Sheet 2 Patented Jan. 9, 1934 PATENTl OFFICE APPARATUS CHRONOUS CIPROCATING ENGINES SYNCHRONISM William Sydney England FOR PARALLELING MACHINES-T0 MAINT Wilson, Erdington,

Albert George Emins,

SYN- AIN RE-` OR PUlVIPS IN Birmingham, and Leamington Spa,

Application January 14, 1932, Serial No. 586,542, and in Great Britain January 14, 1931 5 Claims. (Cl. P11-118) This inventionA such engines arranged by means of synchronous dynamo-electric machines respectively coupled to the two engines and i with one another to run interlocked at the same speed with the direction of rotation of one engine bearing a dennite relationship to the direction of rotation of the other engine and with reciprocating parts of the engines at any instant in pre-f determined relative positions or at predetermined relative points of their cycles of operation. Such arrangements are useful for the purpose reducing vibration. The precise way in which the engines should be interlocked depends on the particular circumstances of the case, but, for example, with a pair o f similar Diesel engines mounted side by side in aship and arranged symmetrically and having their crank shafts parallel or substantially parallel with respect to the vertical plane extending longitudinally of the ship and containing the centre of gravity of the latter itt has gines to run in opposite directions with the re" ciprocating parts of corresponding cylinders of the respective engines at any instant of time similarly disposed so that the power strokes for the two cylinders occur simultaneously. 1t has also been proposed in order to reduce Vibration to fit the twin propellers of a vessel so that they rotate directly out ofsynchronism with one an other. For example, 1n the case of four bladed propellers it was suggested that when two blades of one propeller were in a vertical line, two blades of the other propeller should be displaced by an angle of 45 from the vertical position. In any case the pair of engines must be synchro-y nized, that is to say they must be caused to run in such a way that the reciprocation or cycle of operations of a piston of one engine occurs with or substantially with a definite phase relationship with respect to the reciprocation or cycle of operations of a piston of the other engine and the chief object of the invention is the provision of means whereby this result may readily be obtained with little effort on the part of the operator. f

The invention will now be described by way of example vwith reference to the accompanying diagrammatic drawings in which Figure 1 is a diagram of connections showing the invention applied to two Diesel engines adapted to propel a ship.v the means for operating certain contror 4 mnu-.

contacts being omitted, whilst Figures 2, 3, 4 and 5 illustrate various methods of operating the said contacts.

In Figure 1 the engines l'and 2 are coupled directly to the propeller shafts 3 and 4 and are arranged to drive them in opposite directions The engines which are eight cylinder four stroke Diesel engines, are similar to one another and are disposed symmetrically on opposite sides of centre line of a ship with their crank shafts parallel to or substantially parallel to that centre line, and it is arranged for the cycle of operations of corresponding cylinders of the two engines to occur synchronously. If desired a higher speed may be obtained, but the normal, maximum engine speed is 280 R. P. M.

1 and 2 are arranged respectively to drive two alternating current synchronous dynamo-electric machines 5 and 6 that may be electrically connected and are arranged to operate in such a way that the cycles of operation of corresponding cylinders of the respective engines occur synchronously, means being provided which are adapted automatically to synchronize the machines 5 and 6 whilst corresponding pistons of the respective engines 1 and 2 are at similar points of their cycles of operation. In the form illustrated the synchronizing arrangement comprises means which tend to effect synchronization of the machines 5 and 6 when the latter are in a state suitable for synchronization, and means which prevent synchronization of the machines unless the moving parts of the engines 1 and 2 are respectively in or near the proper relative positions.

The machines 5 and 6 are in the form of 80 kilowatt 24 pole three phase alternators, the field windings being excited from the busbars 10 and l1 connected to a suitable direct current power supply through the switch 7, the field rheostats 8 and the slip rings 9.

It is arranged for the synchronization of the alternators 5 and 6 to be effected by exciting the iield windings of the alternators and by connecting the alternators in parallel through con1 ductors l2, 13 and 14, the connection between the machines first being through a 3-phase choker 15, which, when the voltages of the two machines are substantially equal and the corresponding phase voltages are substantially in opposition, is shortcircuited. Theconnection together of the two alternators through the choker is effected by means of a synchronizing contactor 16 the `operating coil l'l of which is controlled by voltage responsive relay means. The control may be exerted by 2 1,942,789 a single voltmeter relay, but it is preferred to use synchronizing contactor closes and prevent thi l electromagnet exerts a torque which is, say,5 or position. The synchronizing relay 39 is of the less than the torque exerted by the closing contacter type and the contacts 38 thereof are electromagnet which tends to rotate the spindle normally closed, the operating coil 44 of the relay 23 of the relay against the force of a controlling being connected across one phase of the choker ried by the spindle 23, from a stop 26'to a cosuch that only when the alternators 5 and 6 are a calibrated scale. It may also be arranged for ventive contacts 36 are closed, the alternators the force exerted by the closing or/and opening are synchronized by closure of the running con- Inagnet to be adjustable. The two relays are tactor 32.

similarly adjusted and the coil 21 of the closing The preventive contacts 36 and the mechanism electromagnet of the relay 18 and the coil 20 of .for operating them in common with other parts the opening electromagnet of the relay 19 are of the synchronizing gear may take various forms,

25 connected 1n series with one another and on the but in Figure 2 a knife-edged moving contact 46 1 of the opening electromagnet of the relay 18 are them. The contact 46 is mounted on the frame I.'

conductors 13 and 14 joined to two phases of the the easing and meshing with two similar opposaid alternator. The contacts of the relays 18 sitely arranged bevel wheels 50 and 51 also rotatand 19 are connected in series with 'the operating ablv mounted in the casing 48 and driven respec- "1 coil l'l of the synchronizing contacter 16 across tively by the shafts 52 and 54 having bearings Vthe busbars lo and 1l, the circuit including con- 53 and 55 provided on the end of the engine 1. ductor 28, coil 17, conductor 29, contacts 25, 27 The shaft 52 is driven from the half-time shaft of relay 18, conductor 30, contacts 25, 27 of relay 56 of engine l through mitre gear 57 and the 40 19 and conductor 3l. shaft 54 is driven from the half-time shaft 58 11 In operation, when it is wished to effect synof the engine 2 through the mitre gears 59, 62 chronization of the alternators 5 and 6 and of and 64, the shaft 60 provided with bearings 6l the engines l and 2 the field windings of the on the end of the engine 2 and the shaft 63 vcome the combined force of the controlling spring the half- time shafts 56 and 58 respectively. 12'

fers by not more than ve to ten percent from shafts rotate at equal speeds the casing remains 13) together the alternators 5 and 6 through the fore follows that when the shafts 56 and 58 and 3i The synchronizing operation is completed is in a predetermined position and it is arranged through short-circuiting of the choker 15 by clothat only when the contact 46 is in or substansure of a running contactor 32 the operating coil tially in the said position does it engage the con- 33 of which is connected across the busbars 10 tacts 47 and allow synchronization of the alterand 11, the circuit including conductor 34, coil nators 5 and 6 to take place. Once the alterthe contactor to interrupt the circuits of the coils 20, 21 of the relays 18 and 19 and to complete a maintaining circuit for its coil 33. It may be arranged for the moving contact 41 to have more than one predetermined position, for example, the shafts 52 and 54 may be driven to those of the half- time shafts 56 and 58 respectively, in which case there will be two diametrically opposite positions at which two pairs of contacts 47 connected in parallel may be provided severally at such positions for cooperating with the moving contact 46.

In Figure 3 the preventive contacts 66 and 67 are respectively mounted on sliprings 68 and 69 severally secured on the ends of shafts 70 and 71, from which they are insulated, and cooperating with the brushes 72 and 73. The shafts 70 and 71 are in alignment and are driven from the half- time shafts 56 and 58 of the engines manner similar to that in which the shafts 52 and 54 of Figure 2 are driven, but in this case the shafts 71 and 70 are driven in the same direction. The gearing is so arranged that the shafts 7l and 70 respectively run at the same The contacts 66 and 67 are arranged at a definite relative position of the shafts 70 and 71 to engage one another and clearly such position of the shafts 70 and 71 corresponds to a definite relative position of the shafts 56 and 58. Furthermore, the contacts 66 and 67 are so positioned on the shafts 70 and 71 that when the contacts engage the engines l and 2 are in similar positions and corresponding cylinders fire simultaneously. For the sake of clarity the contacts 66 and 67 are shown mounted on spring arms but in practice one of the contacts would be mounted with its contact face fiush with the surface of a disc or cylinder of insulating material carried by the driving shaft so that the other contact would press against and move smoothly over the surface of the disc or cylinder and the contact face. Once the alternators 5 and 6 are synchronized the contacts 66 and 67 move together in engagement with one another.

In Figure 4 mounted on but insulated from the half- time shafts 56 and 58 are the sliprings 75 and 74 respectively cooperating with the brushes 81 and 80, and provided with the arms 77 and 76 carrying the brushes 79 and 78. The brushes 78 and 79 move over the inner surfaces of the axially extending insulated segments 83 of the commutators 85 and 86.

Each commutator is provided with thirty segments and the successive segments 82 of the commutator 85 proceeding in a clockwise direction are respectively connected by conductors 84 to successive segments 83 of the commutator 86 proceeding in a counter-clockwise direction. It follows that when the brushes 78 and 79 are on interconnected segments 82 and 83 there is a circuit between the brush and the brush 81 through slipring 74, arm 76, brush 78, the said segments and a conductor 84, brush 79, arm 77 and slipring 75. The arms 76 and 77 are so positioned relatively to the half- time shafts 58 and 56 that such circuit is made only when the reciprocating parts of corresponding cylinders of the engines are in or approximately in similar positions in their cycles of operations. It will be understood that vthe preventive contacts may be closed when the said parts are, say, `within plus or minus 71/2% of the predetermined relative positions. The brushes 78 and 79 are arranged to engage one segment 82 or 83 before leaving another segment and it therefore follows that when the engines are running in synchronism the circuit through the preventive contacts is maintained.

In Figure 5 the armatures 90 of the auxiliary generators 87 and 88 are mounted on the ends of the half -time shafts of the engines 1 and 2. The generators similar to magnetos and comprise permanent magnets 89 and two-pole shuttle type armatures 90 the windings 91 of which are connected through sliprings 92 and 93 windings 91 of the generators 87 and 88 are connected through the brushes 94 and 95 in series with the winding 97 of a relay provided with preventive contacts 98 and in series with a current limiting choke 96, the arrangement being such that when the corresponding cylinders of the two engines are firing simultaneously the armatures 90 are in similar positions and the voltages of the two generators 87 and 88 in the circuit of the winding 97 are equal and opposite. The moving contact 98 is biased to the close position, but if the moving parts of the two engines are far removed from their correct relative positions in their cycles of operation, since the voltages of generators 87'and 88 are not opposite in through the coil 97 and effects opening of the contacts 98 and the contacts are maintained open parts of theengines including the half- time shafts 56 and 58 are near their proper relative positions when the contacts reclose.

In operation, when the ship has been manuvred out of port, the engines are synchronized merely by exciting the field windings of the alternators 5 and 6 and adjusting the engine throttles until the engine speeds are nearly the same but one engine is very slowly overtaking the other 1/3 of .a cycle per second greater, whereupon the engines having attained or nearly attained the condition in which their reciprocating parts and half- time shafts 56 and 58 are in similar positions the alternators automatically 'synchronize and cause the engines With an arrangement using protective contacts as shown in Figure 2, for example, the operator may, if he wishes, expedite the synchronizing process by watching the moving contact and by slightly speeding up an engine until thecontact is nearly in the permissive position and by then adjusting the throttle and engine speed to that most favourable for effecting synchronization.

Conveniently a synchronizing lamp ork similar device is provided and also an ammeter or wattmeter for indicating the current or power iiow between the alternators 5 and 6 and when the alternators and engines have synchronized the operator may adjust the throttle of an engine to ensure that the engines are properly sharing the load. One great advantage of coupling together the engines electrically as described above is that power may be transferred electrically from one shaft to the other and this operates to equalize the shaft speeds in a storm when the load on one shaft may tend suddenly to vary greatly.

The alternators may be utilized for supplying electrical power for auxiliary services, and in such case their capacity may be suitably increased. The power may be withdrawn directly or through converting apparatus and suitable voltage regulating means will generally be provided.

Suitable protective arrangements will, of course. be provided for protecting the apparatus.

The invention may be ing part of the electric machines when they are rotating at approximately th N. SYDNEY ALBERT GEORGE EMMS.

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