US1847521A - Automatic starting device - Google Patents

Description

March 1, 1932. H, CHANDLER 1,847,521

,AUTQMATIC STARTING DEVICE- Filed Sept. 8, 1928 2 Sheets-Sheet l iaz L n 4.

Inventor .HOMEE P CHA/vaLEE Attorney March 1, 1932. H P. CHANDLER AUTOMATIC STARTING DEVICE Filed Sept. 8, 1928 -2 Sheets-Sheet 2 "null-Ilium mil-in.

14 -35 llli Elm 39 W III-Ill mull-mum I 4 Inventor fi QMEEZ? CfHA/VDLEB Attorney Patented Mar. 1, 1932 .UNITED STATES PATENT OFFICE:

EOMEL I. CHANDLER, OI MANSFIELD, OHIO, ASSIGN'OB TO THE OHIO OOIPANY,

. OF MANSFIELD, OHIO, A CORPORATION OF NEW JERSEY auronrrc sran'rme nnvrcn Application iled September 8, 1988. Serial No. 304,684.

My invention relates to automatic starting devices as applied to electric motors.

The object of m invention is to provide a starting device w ich upon closing the circuit to the motor will throw in series with the motor a resistance to cut down the inrush of current and which will be cut out automatically after a period of time through a mechanism controlled by a thermal element located in apart of the field circuit to the motor, and my invention is further provided with automatic'means for 0 to the motor if the load thereon s ould reach or exceed a predetermined amount.

Other objects of my invention will present themselves to those skilled in the art as I hereinafter describe my invention.

My invention resides in the new and novel construction, combination and relation of the various. parts and circuits hereinafter referred to and shown in the accompanying drawings.

In the drawings Fig. 1 is.a schematic view of my invention shown as connected to a source of power and to an electric motor.

Fig. 2 is a plan view of the cutout and thermal control mechanism therefor and is.

shown in detail and in the open position.

Fig. 3 is a side or edge plan view of Fig. 2.

Fig. 4 is a view cor nding to Fig. 2 with the exception that t e control mechanism is shown in the closed position as'when the starting device is cut out and the motor in full operation.

Fig. 5. is a simplified schematic diagram of the system illustrated in Fig. 1. v v

In the preferred embodiment ofm invention as set forth in Fig. 1, L and L represent the circuits connected to .the source of power. S represents a knife switch for-con:

' trolling circuits to the motor and control mechanism and the source of power. CB

represents an automatic circuit breaker with an operating coil C. M represents a motor.

B res resents a resistance or resistor which is initia ly in series 'with'themotor armature when the switch Sand circuit breaker CB are penin the circuit er is'supplied with a handle and switch mem-v ber 5 and a ivoted latch '6 which engages with the. mem er, 5 to hold it in a closed position with respect to the contact 2. The circuit breaker is provided with an electro magnetic member 7 which is energized by means of the coil C and thereby attracts the latch 6 to permit the circuit breaker to open under the ten sion of the s ring. 5'.

The coil for operating the'circuit breaker is so arranged that if the current through the coil equals or exceeds a predetermined amount, member 7 will. be magnetized sufliciently to attract the latch 6.

The motor M is provided with the field coils I F and the motor armature MA.

Mounted u point intermediate its end by the conductor 8 and the point of connection is such 'that'the' pon the insulated base 1a a" resistor R connected to the coil Get some" same. One end of the co'il 12 is connected to one end of the motor field; by means of the conductor 13; Pivotally"..; ifiounted u n the frame 10 is an armature-14 provid with a reciprocating contactor 15.. Also mounted upon the base 1 is a metal frame 16 provided with a reciprocating contactor 17 tobe engaged by the contact 15 when the armature 14 is attracted by the energizedcore '11. secured to the member 16 is. a phosphor bronse spring contact member 18 which normally engages the top of the contactor '17 and holds 1 thesameinadepressedpodtion. m

rlosed." -A represents the control mechanism by which the is cutout'or short welded together and having difierent coef-v ficients of expansion such that when the bimetal element is heated, it will tend to warp out of shape in a fixed direction due to the unequal ex ansion of the metals of which it is compose Bimetal material is common on the'market and may be composed of two dissimilar metals such as brass and steel.

The bimetal element'T which I use isfconstructed in such a way as to compensate for variations in room temperature as will be later described. One end of the thermal element T is connected to the conductor 13 through the conductor 21 and the other end is provided with a contact 22 which normally engages a fixed .contact 23. When the armature 14 is raised, the contact 15 engages with the contact 17 ,which in turn is raised and with it the spring element 18 and the insulating element 19 engaging the free end of the thermal element T, tends to hold it out of en agement with the contact 23.

ne end of the coil C is connected to the switch blade 5 by means of the conductor 24 and the other end is connected to a branch point 25 b means of the conductor 26. From the branc point 25 a conductor 27 leads to the lower end of the coil 12 and it will be observed that when the switch S and the circuit breaker CB are closed that current will flow from the line L" to the field F through the coils C and 12. Also it will be observed that current will flow from the line L" through the switch S and portion 9 of the coil C, throu h the resistor R to the contact member 16 and from there through the conductor 28 to the armature MA.

It will be noted that the two field coils are connected by the conductor 29 and to the power line L through the conductors 30 and 31, switch S and conductor 32 and that the armature is connected to the power line L through the conductors 33 and 31, switch S and conductor 32. v

It will be noted that a conductor 33 leads from the junction 25 to the fixed contact 23, therefore current will flow from the junction 25, through the conductor 33, the contact 23, thermal element T, conducting su port 20 and conductors 21 and 13 to the field and it will also be noted that by the connections de scribed. the coil 12 is parallel with the thermal element T and, therefore, the current is divided between the thermal element T and coil 12 in flowing to the motor field I llrom the junction 25 a flexible cable leads to the spring-held contact 15 mounted in the armature 14 and insulated therefrom by an insulated bushing35. When the armature 1t is raised, the contact 15 engages with the contact 17 and when this occurs the resistor R is then shunted out or practically so by a circuit breaker GB and c011 G, conductors 26 and 34 and contacts 15 and 17, and conducting support 16. This is brought about since one end of the resistor is connected to the contact support 16 through the conductor 36. In the schematic drawing shown in Fig. 1, all parts are shown in the open or ino erative osition and when the switch S an circuit reaker CB are closed, then a circuit is completed from the source of power to the motor circuit, the resistor R is in series with the armature and also the portion 9 of the coil C and hence the current to the motor is choked and the motor starts under a reduced flow of current and the energization of the portion 9 of the coil C, due to such current, is not sufficient to release the latch 6 of the circuit breaker.

Upon closing the switch S and circuit breaker GB current will also flow through the portions 9 and 37' of the coil C to the junction point 25 where it will divide and flow to the field F of the motor through the coil 12 and the thermal element T, which are in parallel with each other, and the division of current is such that the coil 12 is not energized sufficiently to attract the armature 14. As the motor continues to operate and pick up speed, current through the resistor R will decrease, but the current flowing through the thermal element T will tend to heat the same and cause its free end to bend in a direction away from the fixed contact 23. The heating of the element T requires time, and after a predetermined time the contacts 22 and 23 are broken, thereby destroying the parallel relation between the coil 12 and the thermal element T, and all current to the field F will then flow through the coil 12.

This will energize the coil 12 sufiiciently to attract the armature 14 and when this occurs, the contacts 15 and 17 will engage and when this occurs the resimtor R will then be thrown in parallel with the circuit through the coil C, conductors 26 and 3 1, contacts 15 and 17 and conductor support 16. .The combined resistance of these parallel circuits .will amount to practically nothing and will he the equivalent of throwing the armature directly across the mains'L and L with practically no interposed resistance, and, as already stated, the thermal element T will be thrown out of circuit with the field F and. the motor will be operating directly across the source of power. The fries end or elcment T will he held out of contact with terminal 23-h the insulating; clement In Figs. 2, 3 and 4 the control mechanism, by means of Which the resistor is cut out after a predetermined length of time, is shown in detail and in Figs. 2 and 3 the various contacts are shown in position as when the switches are first closed, and in Fig. v4 the contacts are shown in the operating or normally running position of the motor and which change in contact relation takes place after a predetermined time after the switch S and circuit breaker CB have been closed.

Referring to Figs. 2, 3 and 4, a complete description will probably not'be necessary in view of the description given in connection with Fig. 1. The conducting members 14 and 15 are insulated from each other by the insulating bushing 35 and a spring 38 tends to eject the contact 15, but this is prevented by the pin 39. When the'armature 14 is raised, the contacts 15 and 16 first engage, thus throwing a circuit in parallel with the resistor R. As the armature moves upward- 1y to its final position, the spring 38 is-compressed and forces the contact lfiupwardly, which in turn forces the leaf spring contact 18 upwardly until the insulating strip 19 on its free endengages with .the free end of the bimetal thermal element T, thus holding the contact 22 out of engagement with contact 23 while the motor is under normal operation.

There is no arcing between the contacts 22 and 23 when the circuit is broken at this point due to the fact that the coil 12 is in shunt across the contacts. It will be evident that without means for holding the thermal element T out of contact with the contactorv 23 that as soon as the current ceases to flow through the thermal element T and after the armature has been raised, that the thermal element would immediately begin to cool off due to the thermal element being deprived of the flow of current therethrough, and the free end of the thermal element would then move back .and engage with the contact 23, thus shunting the coil 12 and causing the armature 14 to drop andthu's cutting out the shunt across the resistor R,-which would then again be carrying all the current to the armature. In other words, the

parts of the device would be returned to their-position as when the switch -S and circuit breaker CBwere first closed and the alternate operations of the parts would keep up indefinitely, but through the medium of the free end of the contact 18 and element 19 engaging andholding the thermal element T out of engagement with the contact 23 after the motor has reached normal operation, the alternate cutting in and out of the resistor R'is avoided. The contact 23 ismounted in the conductorsupport 16 and insulated therefrom by means of bimetal and is made in two parts,

of an interposed insulated bushing'40.-

The thermal element T is of rather unique. construction and, as stated before, consists namely 41 and 42, secured together as by the rivet or screw 43. l

The portion 41 has a relatively large cross section, while the portion 42 has a relatively small cross section such that the portion 42 will be affected b the current flowing therethrough and ten to heat the same to cause the metal a: has a lesser coeflicient 0 ex an- .sion than the metal 3 The lower end 0 the part 42 is free to move away from the contact 23 and the metals w and y of which it is composed are oppositely disposed to'the :v'

and y in the art 41 and the tendency is for the lower enci of the part 42 to move to the left with an increase in temperature as the metal y has the greater coeflicient of expansion. From this it will be seen that the free end of the part 41 tends to move to the right while the lower endof the part 42 tends to move to the left with an increase in tem rature" due to the surrounding atmosp ere,

therefore, by properly proportioning the parts 41 and 42, the chan e' in the room temperature is quite accurate y com ensated-for thereby permittin a sin la a ustment or regulation of the t ermal. evice T, which remains quite constant for the majority of conditions under which the device may be used.

In order to regulate the time of operation of the thermal element T, that is the time that is required for it to break its engagement with the contact 23 after the switch S and circuit breaker CB have been closed, may be regulated by the adjustment screw 44.

The adjusting mechanism comprises the.

rigid bar 45 secured to the support 20 by means of the nuts and screws 46, which also secure the fixed end qf the part 41 to the support 20. By manipulatin the screw 44, the relation of the thermal e ement T with respect to thecontact 23 may be altered so as to change the time element of the device.

From the description herein set forth it will be seen that I have provided a device which properly connected to a source of power and to a motor will, upon having the switches closed, throw into series with the armature a resistor R which cuts down the inrush of current and permits the motor to start and increase its speed as time goes on. Also the field is-energized and the thermal element T regulatesthe time in which the resistor R remains alone in circuit with the armature and that as. soon as the thermal element breaks 'its engagement withthe contact 23, the re resistor having tion after the armature 14 has operated to throw the shunt about the resistor R. I

I prefer to place on the core 11 a coil 12 of such turns that the current flowin -therethrough when the shunt about the coiIis open will practically saturate the core, thus permittin the line voltage to drop to a very low value efore the armature 14: will drop and thus draw the entire armature load through the resistor R.

When the device is operated with the resistor- R shunted out, practically all of the current to the motor flows through the parts 9 and 37 of the coil C. A very small portion may go through the part 9 in excess of that flowing through the part 37 due to the resistor connection to the coil C, but this does not afiect the automatic operation of the circuit breaker CB should the load on the motor increase beyond that for which the circuit breaker is set or should trouble develop in the motor.

In order to disconnect the motor from the power lines L and L it is only necessary to open the switch S or the circuit breaker CB, preferably thecircuit breaker CB as this is an automatic switch opening device and may be of the arc blow-out type.

Modifications will sug est themselves to those skilled in the art, t erefore, I wish to be limited only by my claims.

I claim 1. A motor starter comprisin a circuit breaker with a coilto automatica 1y trip the breaker to its open position upon a current flow exceeding a predetermined amount, a

one end connected to the motor and the ot er end to the coil at a point to effect the maximum current flow through a portion of the coil upon closing the breaker,

an electro-magnetically. operated switch in an open position at the time of closing the circuit breaker and arranged when closed to shunt the resistor and direct practieall the entire current flow to the motor throug the entire coil and electro-thermal means to effeet the closing of the switch after current to the motor has flowed for a predetermined time.

2. A control device comprising a resistor, a normally n switch arranged to close and simultaneou y shunt the resistor and having an operating coil, a thermal element normally closin a circuit in shunt with the coil and arrange when heated to open the shunt circuit and efl'ect the energization of the said coil and an operation of the switch to its closed position and means operated by the switch to en age the element to prevent the element closin the shunt, circuit while the switchis close v 3. The combination with a source of power and a motor of a. resistor in series therewith,

and means for automatically shunting the resistor after a predetermined time. of flow of current to the motor and comprising an electritally operated normally open switch, the

switch comprising an operating coil, 9. shut connection about the coil and controlled by a thermally operated switch heated by current from the source of power and when closed preventin closing of the electrically operated switc an armature operated by thesaid coil and carrying a contact, a second contact to be engaged by the first contact and effect the shunting of the resistor, and means operated by the second said contact to prevent the closing of the shunt connection about the coil after the switch contacts have closed the short circuit about the resistor.

4. The combination with a source of power and a motor of a motor starting device comprising a resistor for controlling the initial flow 0 current to the motor armature winding and connected in series with the source of current supply and the motor armature winding an electrically operated switch controlled by a coil connected to the source of power and the motor field winding, a normally closed shunt about the coil, a circuit opening means having a time lag controlling the shunt around the coil and arran ed to open the shunt after current has flowed to the motor for a predetermined time, the switch arranged to close and connect a shunt around the resistor upon the shunt around the coil bein openedand having means to maintain the s unt about the coil open.

5. A motor starting device to connect a motor toa' source of power comprising a resistor for controlling the initial flow of current to the motor armature winding, an electrically operated switch controlled by an electro-magnet having a core and also a coil in series with the source of power and the motor field winding, the ampere turns in the coil being suflicient under normal operation of the motor to saturate the core of the electro-magnet, means having a time lag controlling a shunt about the coil and arran ed to open the-shunt after current has flowe to the motor for a predetermined time, the switch arranged to close and connect a shunt around the resistor. v

6. The combination with a motor and a source of current of a circuit breaker with a coil to automatically trip the breaker to its current flow to the armature winding through the resistor and means to prevent further operation of the electro-thermal element after the shunting switch has closed.

7. The combination with a motor ofa motor starter comprising an electrically controlled switch biased to an open position, a coil to operate the switch to the closedposition, electro-thermal switch connected to initially shunt the coil and connected to the motor and arranged to be heated by the current flowing through the switch and to the motor field winding and break the shunt when heated to a predetermined temperature, a re sister connected to the motor armature winding, the electrically controlled switch arranged to shunt the resistor when the electro thermal switch opens and breaks the shunt, and means to energize the electro-thermal switch to prevent the electro-thermal switch shunting the electrically controlled switch coil after the said switch has closed.

8. The combination with a motor of 'a motor starter comprising an'electrically controlled switch biased to an open position, a coil connected to operate the switch to the closed position and responsive to current to the motor, a bimetal element closing a circuit in shunt with the coil and connected to the motor and arranged to be heated by current flowing through the element to the motor and break the shunt circuit when heated to a predetermined temperature, a resistor connected to the motor armature winding, the electrically controlled switch arranged tov shunt the resistor when the switch closes and means operated by the switch. to engage the bimetallic element to prevent the bimetal element springing the switch coil after the switch has 0 ose 9. A circuit closing device comprising a manually closing and automatically opening switch, a trip coil energized b the current in the circuit controlled'by the evice to release the switch to open when thecurrent reaches a predetermined value, an electro-magnetically operated switch to be energized by a portion of the current in the controlled circuit to close and to automatically increase the sensitivity of the trip coil and a thermally operated switch to control the operation of the electro-magnetic switch to effect the closing of the electro-magnetic switch after current has flowed for a predetermined time.

10. A circuit closing device comprising a circuit breaker provided with a trip coil con.- nected andenergized' by the current in the circuit controlled by the device to automatically release the circuit breaker to open under predetermined current value, a resistor connected in series with the circuit breaker to prevent a rush of current through the cir cuit upon closing the circuit breaker, an electrically operated and thermally controlled mechanism connected to be heated and operated by the current in the circuit to automaticall shunt out the resistor and increase the sensitivity of the tri coil aiter a current of predetermined value as flowed for a predetermined time through the thermally controlled mechanism.

11. A motor starter comprising an electrically controlled switch biased to an open position, a coil to operate the switch to its closed position and responsive to current to the motor field winding, a thermal responsive device initially closing a shunt connection to the coil and connected to be heated in accordance with the current to the motor field winding and lorealr the shunt connection when heated to a predetermined temperature, a resistor connected the motor armature winding to initially conduct current thereto, the electrically controlled switch arranged to shunt the resistor when the switch closes and means controlled by the switch to prevent the thermal responsive device shunting the switch coil after the switch has closed.

12. A circuit controllin device comprising a circuit breaker biase to the open position and having means to hold it releasibly closed and a coil of a plurality of turns to release the holding means when the coil is abnormally energized b current in the circuit controlled by the evice and arranged to have a portion of the turns efl'ective to operate the holding means upon closing the circuit breaker, an electro-magnetically operated switch arranged to close after the circuit breaker has closed and render effective the entire coil, and a thermal responsive device connected to be heated b a portion of the current in the controlled circuit and connected to efi'ect the closing of the electro-magnetically operated switch.

In testimony whereof I aflix my signature..

HOMER P. CHANDLER.

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