US1801133A - Power system - Google Patents

Description

.AP' 1931- V R. A. BEEKMAN 1,801,133

POWER SYSTEM Original Filed Nov. 50, 1927 contac'i' autamatica/[y opens on fial/ in speed Inven'tow:

Royce A.Bee| man, y His AECormey Patented Apr. 14, 1931 UNITED STATES PATENT- OFFICE BOYCE A. BEEKMAN, OF SCHENECTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION NEW YORK rowan. SYSTEM Application filed November 30, 1927, Serial No. 236,839. Renewed April 11, 1930.

My invention relates to improvements in 1o rangement for such a drive is through suitable -reduction gearing. The propeller for eflicient operation must be driven relatively slowly whereas certain types of rime movers can be built to operate most e ciently when 15 running at relatively high speed, for this reason double reduction gearing is usually provided where the main prime mover is a steam turbine. Some other types of prime movers can be operated at relatively lower 20 speed but whatever the type of prime mover and whatever type of mechanical transmission may be provided for driving the pro peller directly from the prime mover a great deal of auxiliary equipment is required on the ship. For example where the prime mover is a steam turbine, boiler feed pumps must be provided for maintaining the necessary level of water inthe boilers for generating the steam for the turbine and much other auxiliary equipment provided. Such equipment may comprise fans for controlling the draft under the boilers, circulating and hot well pumps for the condenser, fans for ventilating the ship, apparatus for handling the cargo and devices for lighting the ship, etc. If the auxiliary equipment is operated I by small steam turbines or reciprocating engines the expense of operating the ship becomes relatively heavy by reason of the fact that such small engines are relatively ineflicienh' The main turbine being a larger unit can be designed to operate much more efficiently than such smaller units.

Ships have been provided with electrically operated auxiliaries, an auxiliary prime mover being provided to drive a generator which supplies motors for operating the various elements of the equipment. This arrangement Secures some increase in efliciency since a single prime mover which superator driven either from plies power for all of the auxiliar load will be considerably larger and more e cient than individual prime movers which would be used for operating the respective devices.

According to my invention the auxiliaries are electrically operated but during most of the time that the ship is in operation the power for driving such auxiliaries is derived from the main turbine which drives the ships propeller. Since in direct drive ships as distinguished from electrically driven ships there is no main generator, I provide a genthe main prime mover shaft or from some element of the gearing between such prime mover and the propeller. If the main prime mover is normally operated at a very high speed it is ad vantageous to'drive the generator from one of the intermediate gears since the generator may be more readily designed for a moderate speed of operation.

One of the difficulties encountered in attempting to operate the auxiliary equipment from a generator driven from the prime mover of a ship propulsion system is due to the fact that the speed of the prime mover varies through a wide range. The speed of the prime mover may be adjusted by a throttle valve or the like. In steam turbine driven ships of the electric drive type for example it is common to provide means such as a'speed control lever for setting a speed governing means of the turbine. The governing -means which may be of any suitable type,

such as a centrifugal governor or oil pressure governor, operates to hold the speed of the turbine constant for any given setting of the speed control lever. Changes in load due to headwinds or waves or brought about by turning the ship are automatically taken care of by the speed'governor,-but the particular speedwhich is held substantially constant by the speed governor is changed by different settings of the speed lever. An example of this type of control is disclosed in Letters Patent to Emmet, No. 1,137,308, dated April 27, 1915. Since the prime mover thus operates over a wide range of speed it becomes unsuitable as a source of power for H as an'ideal system, this refinement is not at all essential to-the practical application of my nvention, andiniships for certain classes of service it is sufficient-1 tosuse a throttle lever or the like for speed control while relying upon an emergency governor, which may, for example, beof the centrifugal type, to shut ofl the powerif a predetermined speed is exceeded.

In accordance with my invention I supply the auxiliary equipment from a generator driven from the main prime mover while the speed of such main prime mover is suitable, and provide an auxiliary source of power which assumes the load of the auxiliary equipment when the main prime mover becomes un suitable as a source of power and provide improved control devices for thus transferring the auxiliary load to the. auxiliary prime mover. I thus secure the advantage of the more elficient operation of the main prime mover during most of the time the ship is in operation while'securing reliability of service of the auxiliary equipment from an auxiliary power supply which takes up the load only when necessary.

My invention will be better understood from the following'description considered in connection with the accompanying drawing and its scope will be pointed out in the appended claims. q

The drawing, Fig. 1, diagrammatically represents a ship propulsion system showing one embodiment'of my invention and Fig. 2 diagrammatically represents one modification thereof.

Referring to Fig. 1-, a propeller 1 is diagrammaticallyillustrated as driven through reduction gearing from a prime mover, indicated as a steam turbine 2. A generator 3 is erator 3 the circuit breaker 6 is'open and the auxiliary prime mover, indicated as a turbine 7, operates to drive the auxiliary dynamo-electric machine 8 as a generator to supply power to the auxiliary circuit 5.

While the generator 3 is supplying power.

for the auxiliary equipment the dynamo-electric machine 8 remains connected to the aux iliary circuit 5 and operates as a motor to drive the turbine 7 idle.

In the particular arrangement diagrammaticaly illustrated, a secondturbine 2 is shown for assisting in driving the propeller 1. As illustrated this second turbine 2 is a low pressure turbine operated by steam exhausted from the turbine 2 through means indicated by the pipe 9.- It is to be understood however that my invention is not limited to any particular type of prime mover nor to any particular type of mechanical transmission between the prime moverand the propeller. Means are ordinarily provided in a ship propulsion system for reversing the operation of the propeller but as such means form no part of my present invention it has not been indicated on the drawing.

The speed controlling lever for adjusting the speed of the main turbine is diagrammatically indicated at 10. As far as my invention is concerned this speed lever 10 may be regarded as a throttle lever for any suitable prime mover whether of the steam, gas or other type. In the arrangement diagrammatically illustrated it is indicated as operating through a connection 11 to adjust the overnor or throttle valve of the turbine 2 w ich governor or throttle valve is not shown in detail, but may be considered to be represented by the part 12. The auxiliary turbine 7 may be provided with a governor represented by the part 13. This governor will preferably be adjustable according to the broad principle of the Emmet patent above referred to; The governor of the auxiliary turbine 7 is set so that it admits steam to this turbine when its speed. tends to fall below a predetermined desired value. As heretofore stated, when the speed of the main turbine falls below a value suitable for supplying the auxiliary equipment the auxiliary unit 7, 8 becomes operative to supply such equipment. The bro-ad idea of arranging the governing means of an auxiliary turbine to admit steam thereto when the speed tends to fall below a predetermined value is old in the art. One example of such idea of means is disclosed in Letters Patent to Clarke, No. 1,185,288, dated May 30, 1916. In the Clarke arrangement a dual drive is rovided for an individual unit of the auxillary equipment of a power station. Normally such element is driven by an induction motor supplied from a power systemand when the power system fails, so that the speed of the dual drive unit tends to fall below a predetermined value, steam is admitted to the turblue to take over the load of the driven ele- ,ment, the induction motor being then dis- -8 remains connected to the auxiliary circuit.

While the main generator 3 is connected to 14 is provided for engaging the lever 10 to prevent vfurther movement in its speed reducing direction until the stop device has been moved out of the way. For example the speed lever 10 may have 20 .or more points of adjustment to vary the speed ofthe main turbine over a rangefrom 3600 R. P. M. down to 1200 R. P. M., and the stop device 14 may be arranged to engage the speed lever at a point of adjustment corresponding to speed, or 2700 RIP. M. In order-to adjust the speed of the turbine to something below 2700 R. P. M., in the exam: ple given, the stop device 14 must be moved out of the way. In Fig. 1 I have illustrated means whereby movement of the stop device 14 opens the circuit breaker 6 between the generator 3 and the auxiliary circuitb and also causes steam to be admitted to the auxiliary turbine 7. To admit steam to the auxiliary turbine a connection 15 is provided between the stop device and a speed control lever 16 for the governor '13 of the auxiliary turbine 7. To open the circuit breaker 6 I provide a contact 17 on the stop device 14 which contact is o ened when the stop device ismoved. In t earrangement illustrated the circuitbreaker 6 is of the latched-in type and when the contact 17 is opened the tripping solenoid 18 of the circuit breaker is deenergized to knock out'the latch 19 and permit the circuit breaker to be opened by the spring 20. It will be apparent to those .skilled in the art, however,

\ that my invention is not limited to any particular type of circuit breaker since many examples of circuit breakers are 'known which may be incorporated in my arrangement to secure the cooperative relationship which I desire.

It will be observed that'in the arrangement shown in 'Fig. 1 the control circuit for the circuit breaker 6, which control circuit leads through the'solenoid 18, is connected so that cause of some abnormal condition the speed of the main turbine should. fall to a low value notwithstanding the fact that the speed lever 10 may be within a range above that of a the setting of the device 14,'the speed and-voltage of the. generator 3 may be so low as'to cause the circuit breaker 6 to be tripped open; If this hap ens the governor of the auxiliary turbine will immediately cause such auxiliary turbineto pick up the load of the auxilia equipment which will thus be maintained in continuous operation.

In the drawing I have illustrated a regulating means 21for the generator 3. This is) indicated as a variable resistance in the field Q circuit of the generator. I prefer to make this regulating means automatic in operation so as to maintain the voltage of the generator 3 substantially constant over a considerable speed change, preferably down to a speed substantially corresponding to the setting of the stop device 14. The particular type of regulating means used is immaterial, many examples of suitable regulating means being well-known in the art. Such automatic regulating means is desirable in that it maintains the voltage impressed on the auxiliary circuit substantially constant throughout the speed range of the main turbine during which the generator 3 supplies the auxiliary circuit and thereby secures better operation of the auxiiliary equipment than would be secured with a variable voltage. The opening of the cir cuit breaker 6 on small changes in the speed of the generator 3 is also prevented, but if the speed falls below a predetermined point the regulating means 21 will be unable to hold the voltage up and the circuit breaker 6 will open to disconnect thegenerator 3 from the auxiliary circuit and permit it to be supplied by the auxiliary unit 7,8. g

Since the dynamo-electric machine-80f the auxiliary unit operates as amotor supplied from the generator 3 while that generator is supplying the auxiliary equipment and the speed of the motor decreases with. decrease in the voltage of the main nerator, it is apparent to those skilled in ti e art that means directly responsive to the s of the auxiliary unit'may be provid for opening the circuit breaker 6 to disconnect the "generator 3 from 'thehuxiliary circuit 5. This arrangement is diagrammatically indicated in Fig. 2 where a contact 22 controlled automatically by the governor 13' of the turbine 7, as indicated'by the dotted connection 23, is arranged to open automatically upon a fall in it will be energized in accordance with the? speed of the turbine. The contact 22 in the voltage of the generator 3 when that generator is supplyingthe auxiliary circuit 5 The opening of the circuit breaker is therefore made responsive to a predetermined change in the voltage of generator 3 and like Wise to a predetermined change in the speed of the main turbine 2. If, for example, be-

arrangement illustrated in Fig. 2 is in series with the tripping solenoid 18 of the circuit breaker 6, so that when the contact 22 opens on a fall in speed of the turbine, the solenoid 18- is deenergized to trip the circuit breaker open and disconnect the main generator from the auxiliary circuit, leaving it supplied by auxiliary unit 7, 8. As in the arrangement of Fig. 1 the solenoid 18 will itself trip the circuit breaker 6 open upon a predetermined fall in voltage.

While I have illustrated an embodiment'of my invention utilizing dynamo-electric machines of the direct current type, it will be apparent to those skilled in the art, in the light of my disclosure, that alternating current dynamo-electric machinery may be used without departing from my invention. While my invention is particularly adaptedto ship propulsion systems of the direct drive type, it will also be apparent that certain features of my invention are applicable to electrically driven ships. For example, the idea of adj usting the speed of the auxiliary prime mover, 7 by the stop device 14, or some equivalent arrangement providing an adjustment of the admission to the auxiliary prime mover '00- operatively related to the speed control lever of the main prime mover, is applicable Without change to an electrically driven ship and to power systems other than ship propulsion systems. This feature has the advantage of adjusting the admission to the auxiliary prime mover to enable it to pick up the aux-- iliary load without waiting for the speed of the auxiliary unit to drop an amount suf ficient to cause the governor of the auxiliary unit to become effective to increase the admission. The auxiliary load may thus be taken over by the auxiliary unit with a quite negligible change in the voltage on the auxiliary circuit. Indeed the adjustment made by the movement of my stop device 14 may be such as to increase the normal speed of the auxiliary prime mover 7 so that the voltage on the auxiliary circuit is actually raised somewhat above the voltage which would normally exist thereon at the time the circuit breaker 6 is opened to disconnect themain generator 3.

From the foregoing description it is apparent that various changes and modifications' may be made in the particular devices used and the arrangement and application of such devices without departing from my invention and I therefore aim in the appended.

the prime mover to the propeller, means for adjusting the speed of the prime mover through a relatively wide range to control the speed of the ship, agenerator mechanically drlven from said prime mover, a load circuit having auxiliary equipment connected thereto, switching means between said generator and load circuit, an auxiliary unit comprising a prime mover and a dynamo-electric machine, said dynamo-electric machine being connected. to said load circuit to operate as a motor to drive said prime mover and as a generator to supply said load cirvcuit,-and means for operating said switch to disconnect the generator driven by the main prime mover from the load circuit and for in-. creasing the speed of the auxiliary prime mover when the speed of the main prime mover driven generator is adjusted to a value too low for satisfactory operation of the auxiliary equipment from said generator.

2. A ship propulsion system comprising a main prime mover and a propeller geared thereto, means for adjusting the speed of the prime mover through a relatively wide range to control the speed of the ship, a generator mechanically driven from said main prime mover, a load circuit havin auxiliary equipment connected thereto ad apted to be supplied from said generator, an auxiliary prime mover, a dynamo-electric machine connected to said load circuit, said auxiliary dynamoelectric machine adapted to operate as a motor to drive said-auxiliary prime mover and as a generator driven thereby, and means re.- sponsive to the voltage of the generator driven from the main turbine for disconnecting said generator from the load circuit when the voltage falls below a predetermined value.

3. A power system comprising a prime mover mechanically geared to a load device,

means for adjusting the speed of the prime mover through a relatively wide range, a generator mechanically driven from said prime mover, a load circuit having auxiliary equipment connected thereto arranged to be supplied from said generator, an auxiliary unit' comprising a prime mover. and dynamo-electric machine, said dynamo-electric machine being connected to said load'circuit and arranged to drive said auxiliary prime mover when the voltage of the load circuit is above a predetermined value and arranged to be driven by said auxiliary prime mover and operate to supply said load circuit when the voltage of the load circuit falls below a pre- 1 determined value, andme'ans for automatically disconnecting said generator from the load circuit when the speed of the main prime mover is below that suitable for said generator satisfactorily to operate the auxiliary equipment and regulating means ar ranged to maintain the voltage of said generator substantially constant for a certain range of speed variation to prevent disconnection of said generator from the load circuit u on changes in speed of the main turbine wit the range of operation of said regulating means.

4. A power system comprising a main prime mover, a generator driven from saidprime mover, a load circuit having auxiliary equipment connected thereto arranged to be supplied from said generator, an auxiliary unit comprising a prime mover and 'a dynamo-electric machine, said dynamo-electric machine being connected to said load circuit to operate as a motor to drive said auxiliary prime mover and as a generator driven by said auxiliary prime mover to supply the load circuit, a speed adjusting device for adjusting the speed of the main prime mover through a relatively Wide range, a movable stop device for preventing movement of said speed adjusting device beyond a predetermined position in the speed reducing direction until said stop device is moved, speed controlling means for said auxiliary prime mover and means controlled by movement of said stop device for disconnecting said generator from said load circuit and increasing the speed of said auxiliary turbine.

5. A power system comprising a main prime mover and a generator driven therefrom, a load circuit connected to said generator, a switch between said generator and load circuit, an auxiliary unit comprising a turbine and dynamo-electric machine, said dynamo-electric machine being connected to said load circuit, a speed adjusting device for adjusting the speed of said main prime mover through a relatively wide range, a movable stop device cooperating with said speed adjusting device to limit further speed reduction of the main turbine until the stop device is moved, means controlled by movement of the stop device for speeding up the auxiliary turbine and means conjointly controlled by the voltage of said generator and by said stop device for opening said switch to disconnect said generator from said load circuit.

In witness whereof, I have hereunto set my hand this 29th day of November, 1927.

ROYCE A. BEEKMAN.

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