FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
POWER SAVING CONTACTOR;
LARSEN & TOUBRO LIMITED, A COMPANY INCORPORATED UNDER THE COMPANIES ACT, 1956, WHOSE ADDRESS IS L&T HOUSE, BALLARD ESTATE, MUMBAI - 400 001, MAHARASHTRA, INDIA.
THE FOLLOWING SPECIFICATION
PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.

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TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetically latched power saving contactor.
BACKGROUND OF THE PRESENT INVENTION
A contactor is used for switching loads with a controlled power flow, which is activated by an electric power.
The contactor is composed of three different system, a contact system (a ac control system or a dc control system), a electromagent system, and an insulated housing system. The contact system consists of a current carrying part of the contactor, which when close results the current to flow further in a circuit. The contact system includes a power contact, a auxiliary contact and a contact spring arrangement for flowing current in the circuit. The electromagnet system is a driving unit of the contact system, which provides intended force to close the contact system. The insulated system is an external frame housing of the contact system and the electromagent system.
Aforesaid electromagnet system is electrically and magnetically formed in such a way that little electric power is to be applied in holding state of magnets.
Devices like PLC and other electronic drives, which are used for switching contactor with the dc control system, due to swtching through low power active electronic components under the holding state, restricts their usage for low power. Therefore, there have been regular demand of the contactor, which comsume low electric power.
Ealier methodology for the dc control system type contactor is to opt for a pure coil with increase in number of turns of the coil, to maintain the continuous electric power with desired pick-up. Increase in the number of turns of the coil, increases the hold on voltage and height of the coil. This increase in the height
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of the coil, increases overall volume of the enclosure system. Also, the power consumed by such devices are very high.
Over the years, various type of contactors are introduced to overcome the aforesaid problems. Some of the contactor solving said problems are; a dc coil with economy resistor and late break "NC", a dc coil with dual winding and late break "NC", a low consumption dc coil with permanent magnet based technology and, a dc coil with electronically controlled coil drive for "low wattage" consumption.
All mentioned contactors are able to eliminate aforesaid problem of higher volume of the insulator system by reducing a copper area of the coil. But, with all these methodology followed, the aforesaid contactors consumes higher hold-on power during closing condition.
To overcome the problems associated with the earlier methodology, an economic power despatch circuit is often installed with a magnetically latched contactor. But even in the economizer circuit, large amount of electric power is required to initially close the contactor and thereafter the electric power is further required to keep the contactor in hold-on closed position. Said circuits can save substantial amount of electric power, and allow the energized coil to stay cooler, but it still consuming higher hold-on power.
Hence, there is a need for a new and improved contactor, which eliminates the aforesaid problems in various type of the contactors.
SUMMARY OF EMBODIMENTS OF THE INVENTION
According to one embodiment, the invention provides a power saving contactor, comprising: a selectively energizable coil; a moving contact member and a fixed contact member magnetized by the energized coil, which latch and de-
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latch with respect to each other on changeover in a voltage polarity of the energized coil; plurality of retainers assembled the fixed contact member; atleast one permanent magnet associated to the retainers for generating magnetic flux to hold the moving contact member and the fixed contact member at the latched position; and an electronic module for energizing and de-energizing the coil for latching and de-latching the moving contact member and the fixed contact member, wherein the electronic module cuts the power to de-energize the coil when the permanent magnet with the retainers holds the moving contact member and the fixed contact member at the latched position.
The invention according to one embodiment, provided the electronic module provided within a detachably attachable moulded housing for a contactor incorporating a selectively energizable coil, the electronic module comprises: atleast two sensor for sensing voltage from an electrical source; atleast two switch for electrical interlocking and isolation of the voltage sensed by the sensors; an indicator for indicating electrical interlocking and isolation of the voltage; an indicator timer for timing status indication in the indicator; a controller timer along with a MOSFET to charge a capacitor on interlocking of the voltage and to provide controlled positive pulse to coil; and the capacitor for charging and discharge of the voltage, wherein the electronic module including said sensors, configured to detect short circuits or overload voltage and send a command signal to the coil of the contactor.
According to another embodiment of the invention, the electronic module is being provided within a moulded housing along with the contactor.
In one embodiment, the power saving contactor incorporates the two retainers along with one permanent magnet, which is assembled to the one end of the
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fixed contact member, and the two another retainers along with another permanent magnet is assembled to the another end of the fixed contact member.
In another embodiment, the power saving contactor incorporates the two retainers along with one permanent magnet anywhere on the fixed contact member.
An air gap part is kept between said retainers and the permanent magnet, the air gap part is kept to reduce contour of the of magnetic field created by the permanent magnet to generate strong holding force, which holds the moving contact member and the fixed contact member strongly without any external voltage required from the electric sources.
In one embodiment, the power saving contactor incorporates a restraining spring, which extents within the moving contact member and the fixed contact member. The moving contact member being arranged to rest on one side of the spring, and the coil and the permanent magnet associated with said retainers on the fixed contact member being arranged on the other side of the spring within the moulded housing of the power saving contactor.
In one embodiment, an indicator being attached to the electronic module for indicating the latch and de-latch positions of the contactor.
Hereinafter the description supported with figures is set forth for purpose of explanation in order to provide an understanding of the invention. However, it is apparent that one skilled in the art will recognize that embodiments described in the summary are hereinafter described in the description. Moreover, the structures shown below in the figures are illustrative of embodiments of the invention and are meant to avoid obscuring of the invention. Furthermore,
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connections between components within the figure are not intended to limit the direct connection. Rather, data between the elements may be modified, reformatted or otherwise changed by intermediary components.
Reference in the specification to "one embodiment", "in one embodiment" or "an embodiment" etc. means that a particular feature, structure, characteristic, or function described in connection with the embodiment is included in at least one embodiment of the invention. The appearances of the phrase "one embodiment" in various places on the specification are not necessarily all referring to the same embodiment.
DRAWINGS OF EMBODIMENTS OF THE INVENTION
Fig. 1 shows a block diagram of a power saving contactor according to the preferred embodiment of the invention.
Fig. 2 shows a sectional view of the magnet system, according to one embodiment of the invention.
Fig. 3 shows a front view of the magnetically latched contactor, according to one embodiment of the invention.
Fig. 4 shows a sectional view of the magnetically latched contactor, according to one embodiment of the invention.
Fig.5 shows a circuit diagram for an electronic module, according to one embodiment of the invention.
Fig. 6 shows the electronic module with a moulded housing, according to one embodiment of the invention.
Fig. 7 shows an integral, unitary structure of the power saving contactor, according to one embodiment of the invention.
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Fig. 8 shows a non-integral, non-unitary structure of the power saving contactor, according to one embodiment of the invention.
DESCRIPTION OF THE EMBODIMENTS OF THE INVENTION
A block diagram of a power saving contactor (100) according to the preferred embodiment of the invention is shown in Fig.1. The power saving contactor (100) comprises of an electronic module (110) and a magnetically latched contactor (120). The electronic device (110) consists of a momentary self-power generation unit (112), a control circuit (114) and a status indicator (116). The electronic module (110) is associated with a magnetically latched contactor (120) that has a coil (122), an assembly (124) of a moving contact member and a fixed contact member having permanent magnets connected to the ends of the fixed contact member. The moving contact member and the fixed contact member respectively are moving electromagnet and a fixed electromagnet. A power from a power supply unit (130) is fed to the electronic device (110), which is suitably rectified and filtered into regulated dc supply and then fed to the coil (122). The moving electromagnet and the fixed electromagnet of the contactor (120) gets latched by the supply voltage fed into the coil (122) at a desired preset operating voltage and remains in the latched condition due to the permanent magnet flux generating from the parmanent magnets. The power to the contactor (120) is then cut-off by the electronic module (110), as the power saving contactor (100) does not require any extra power to be kept in the hold-on position. The power saving contactor (100) unlike conventional contactors does not consume any hold-on power to be kept in the latched position. An auxiliary switch in the electronic module (110) ensures that there is no negative supply fed across the coil when the range of supply voltage is from 35% to 65 %. When the supply voltage falls down below 35% of the rated
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voltage or the supply power, the electronic module (110) connected to the contactor (120), develops a short time voltage pulse with sufficient magneto motive force (mmf) in the reverse polarity to feed across the coil (122) to de-latch the moving and the fixed electromagnets.
In one embodiment, Fig. 2 shows sectional view of the magnet system which consists of a moving contact assembly (210) and a fixed contact assembly (220). The moving contact assembly (210) consists of a moving electromagnet (212) with a leaf spring (214), which is press fit with a bridge assembly (216). The fixed magnet assembly (220) consists of a fixed electromagnet (222), two permanent magnet (224 and 226), plurality of permanent magnet retainers (224a &224b) and (226a & 226b), and an air gap part (228). The two permanent magnet (224) and (226) are suitably placed to the adjacent side at the ends of the fixed electromagnet (222). The two permanent magnet retainers (224a) and (224b) are suitably placed at the bottom & top portion of the permanent magnet (224) at one end of fixed electromagnet (222). The other two permanent magnet retainers (226a) and (226b) are suitably placed at the bottom & top portion of the permanent magnet (226) at the other end of fixed electromagnet (222).The permanent magnet along with the retainers are placed at the adjacent side of the fixed magnet to generate the flux with the shortest path available in the magnetic circuit. Alternatively, the permanent magnets (224) and (226) can be suitably placed any where on the fixed electromagnet (220) as per the requirement. The air gap part (228) provided between the reatiners (224a & 224b) and (226a & 226b) and the permanent magnets (224) and (226) by means of an insulated spacer to avoid shorting of the permanent magnet.
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Fig. 3 shows a front view of the magnetically latched contactor and Fig. 4 shows a sectional view of the same. The magnetically latched contactor (120) consists of a top cover (300) having a click fit transparent lens (310) for indicating "ON" & "OFF" condition of the contactor. The magnetically latched contactor (120) further incorporates a front housing (320) along with arc interruption components (400), a fixed contact assembly (410), a moving contact assembly with a bridge assembly (420). The moving contact assembly with a bridge assembly (420) has the moving electromagnet (330).
The electromagnetic system for the contactor is of E - E type assembly. The moving contact assembly with the bridge assembly (420) is secured to the fixed electromagnet assembly by means of a leaf spring (214).
The magnet assembly, which consist of a moving electromagnet (330), a fixed electromagnet (430), a coil and coil former (350), a coil terminal assembly (360), a return spring (370) and an insulated rubber pad (380), wherein the return spring (370) and the insulated rubber pad (380) is provided for dampening the shock and vibration of the magnet and a rear housing (390).
The front housing (320) attached to the base housing by screws or other means. The arc-interrupting device (400) is guided by slotted ribs provided on each pole of the arc shield (300) of the front housing (320). The bridge (420) along with a moving assembly is secured and guided in the front housing (320) along the entire width the magnetically latched contactor (120).
The moving contact assembly (440) is placed inside a slotted window provided along with the bridge (420) beneath the contact spring for exerting a desired pressure for de-latching the contacts. The bottom part of the moving assembly
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include a moving magnet assembly (330) that is guided by a bridge strap (340) of the bridge assembly by a leaf spring. The whole of the moving assembly (420,340 and 330) along with the return spring (370) is enclosed between the moving magnet, and the coil former (350) is suitably placed inside the fixed electronmagnet assembly.
The L-shaped insulated arc shield plate is provided in the arc shield (300) of the contactor (120). As shown in the said above Fig. 3 and Fig. 4, circular insulated ribs on the top cover (300) provides accessibility of the indicating and measuring probe of the contactor (120). The arc shield cover is secured on the front housing (320) by means of a screws or other means.
According to another embobiment, Fig. 5 shows the circuit diagram (500) for the electronic module (110). The electronic module (110) includes two interlocking sensors cum switches (510 & 520), which controls a threshold voltage for the latched and de-latching condition of the contactor (120). A timer (530) activates the indicator (116) indicating the status of the contactor (120) at normal "ON", abnormal and under-voltage condition. A timer (540) serves the purpose of controlling a MOSFET (550) circuit. A normally open & a closed contacts (560 and (570) of the sensor & switches (510 and 520) serves the purpose of electrical interlocking and isolation of power supply for the power saving contactor at "ON" & "OFF" conditions. The circuitary (500) along with it's components is placed inside the moulded housing (600) as shown in Fig. 6. For mounting of the electronic module (110) with the contactor (120), a ring type snap ON terminals (610) are provided. On the other side, flat blade type snap on terminals (620) are provided for entry of quick connect type lug. Further, for removal and insertation of the electronic components from the contactor (120), a click fit cover (630) is provided with the housing. Inside the
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housing, a separate compartment is provided for accommodating the self power generating unit, which is replaceable in the event of damage against surges or undue fault for supporting of the, which is hinged (640) with the housing. The electronic module (110) can be separately mounted on a base plate or on a din rail. Alternatively, the electronic module (110) can be mounted along with the contactor. The housing has a base plate (650) which has pluraltiy of holes (660) to incorporates screws.
Refering back to Fig.5 when a positive pulse is supplied, the sensor cum switch (520) picks up thereby isolating the capacitor (580) from the main circuit. As the voltage increases, the switch (510) operates at a pre set operating voltage, which closes the normally open (NO) contact (560). Simultaneously, both the timers (530) and (540) with preset duty cycle turns "ON". The output of timer (540) is fed to the input circuit of the MOSFET (550) to turn it on. The coil (590) of the contactor gets supply voltage from the MOSFET (550), which switches "ON" the contactor at preset operating voltage. The entire voltage then appears across the branch constituting of resistors & capacitor. The capacitor (580) gets charged to a full control voltage by the supply voltage from the MOSFET (550) via circuit. The timer (540) is set with a desired "ON" time that turns "OFF" the MOSFET (550) after the time is complete. Once the MOSFET (550) turns "OFF" the control supply to contactor coil (590) is cut off. The branch circuit consisting of the resistors and the capacitors (580) will be still in the main circuit. During this process, the timer (530) blinks the red LED indicating "on" condition and it blinks till there is positive control supply to the contactor. The electronic module (110) provides a advantage for adjusting the duty cycle of the timer and that of the operating threshold voltage.
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Eventually, when the control voltage reduces below 35 % of the rated voltage or there is no supply, the sensor cum switch (510) drops down for cutting off the control supply to the switch (520), which in-turn turns OFF the capacitor circuit. The electrical interlocking contacts of the switch (520) connect the charged capacitor (580) across the coil. The reverse pulse generated by the capacitor (580), gets discharged through the contactor coil (590), which produces a flux opposite to the flux developed by the permanent magnets. The resultant flux density generated by the permanent magnets flux and the coil flux is below the operating load point that reduces the holding force between the fixed and moving electromagnet. The reduction in the holding force de-latch the fixed and moving electromagnet of the contactor.
The power saving contactor in contrast to a magnetically or mechanically latched contactor, is a fail safe contactor. The power saving contactor similar to that of a conventional contactor, automatically generates power at power cut condition or any fault condition preventing material loss, production loss etc.
The power saving contactor reduces overall voltage consumption of the contactor for a complete cycle of operation (ON-HOLD-ON-OFF). It avoids coil burning and guards against all types of field failure due to abnormal condition such as variation in system voltage, generation of system harmonics and switching surges. Due to placement of the permanent magnet there is reduction of substantial amount of material in the coils that result said small and compact power saving contactor. There is also reduction of the sluggish movement of the bridge assembly the power saving contactor as compared to
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the conventional DC control contactor. The power saving contactor avoids chattering of contactor during pick-up and drop-out condition. Further, there is improvement in the breaking capacity of the contactor owing to higher restraining stored energy. The power saving contactor can be used for both ac as well as dc control supply and is suitable as well for lighting duty application.
The power saving contactor (100) according to the disclosed embodiments of the present invention is of simple construction, and is manufactured as an integral, unitary structure as shown in Fig. 7. The power saving contactor according to the disclosed embodiments can be can be manufactured as an non-integral, non-unitary structure as shown in Fig. 8.
The power saving contactor according to the disclosed embodiments of the present invention may be manufactured in a variety of sizes to suit any of the aforementioned applications. Also, the power saving contactor may be constructed with its various elements, located on either of the respective elements without limitation or adverse effect upon its operation.
It is to be understood that the invention is not limited to the illustrations described and shown herein, which are deemed to be merely illustrative of the best modes of carrying out the invention, and which are suitable of modification of form, size, arrangement of parts and details of operation. The invention rather is intended to encompass all such modifications, which are within the spirit and scope and defined by the claims.
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WE CLAIM
1. A power saving contactor, comprising :
a selectively energizable coil;
a moving contact member and a fixed contact member magnetized by the energized coil, which latch and de-latch each other on changeover in a voltage polarity of the energized coil;
plurality of retainers assembled the fixed contact member;
atleast one permanent magnet associated to the retainers for generating magnetic flux to hold the moving contact member and the fixed contact member at the latched position; and
an electronic module for energizing and de-energizing the coil for latching and de-latching the moving contact member and the fixed contact member,
wherein the electronic module cuts the power to de-energize the coil when the permanent magnet with the retainers holds the moving contact member and the fixed contact member at the latched position.
2. The power saving contactor as claimed in claim 1, wherein the power saving contactor is provided within a moulded housing.
3. The power saving contactor as claimed in claim 1, wherein the power saving contactor being for a.c. control supply.
4. The power saving contactor as claimed in claim 1, wherein the power saving contactor being for d.c. control supply.
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5. The power saving contactor as claimed in claim 1, wherein the selectively energizable coil being independent of abnormal and faulty condition of the voltage.
6. The power saving contactor as claimed in any of the preceding claims, wherein the two retainers along with one permanent magnet is assembled to the one end of the fixed contact member, and the two another retainers along with another permanent magnet is assembled to the another end of the fixed contact member.
7. The power saving contactor as claimed in any of the preceding claims, wherein an air gap part is kept between said retainers and the permanent magnet.
8. The power saving contactor as claimed in claim 1, wherein the electronic module is provided within a detachably attached moulded housing to attach with the contactor.
9. The power saving contactor as claimed in claim 1 wherein, the electronic module being provided within the moulded housing along with the contactor.

10. The power saving contactor as claimed in claim 1, wherein a spring extents within the moving contact member and the fixed contact member.
11. The power saving contactor as claimed in any of the preceding claims, wherein the moving member being arranged to rest on one side of the spring, and the coil and the permanent magnet associated with said retainers on the fixed contact member being arrange on the other side of the spring within the moulded housing of the power saving contactor.
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12. The power saving contactor as claimed in any of the preceding claims wherein, an indicator being attached to the electronic module for indicating the latch and de-latch positions of the contactor
13. The power saving contactor as claimed in any of the preceding claims substantially as herein described, with reference to and as illustrated in the accompanying figures.
14. An electronic module provided within a detachably attachable moulded housing for a contactor incorporating a selectively energizable coil, the electronic module comprising :
atleast two sensor for sensing voltage from an electrical source;
atleast two switch for electrical interlocking and isolation of the voltage sensed by the sensors;
an indicator for indicating electrical interlocking and isolation of the voltage;
an indicator timer for timing status indication in the indicator;
a controller timer along with a MOSFET to charge a capacitor on interlocking of the voltage; and
the capacitor for charging and discharge of the voltage,
wherein the electronic module including said sensors, configured to detect short circuits or overload voltage and send a command signal to the coil of the contactor.
15. The electronic module as claimed in claim 14 wherein, the electronic
module being provided within a moulded housing.
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16. The electronic module as claimed in claim 14 wherein the electronic module is provided within a detachably attached moulded housing to attach with the contactor.
17. The electronic module as claimed in any of the preceding claims substantially as herein described, with reference to and as illustrated in the accompanying figures.

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ABSTRACT
An invention provides a power saving contactor provided within a moulded housing comprises a selectively energizable coil; a moving contact member and a fixed contact member magnetized by the energized coil, which latch and de-latch each other on changeover in a voltage polarity of the energized coil; plurality of retainers assembled the fixed contact member; atleast one permanent magnet associated to the retainers for generating magnetic flux to hold the moving contact member and the fixed contact member at the latched position; and an electronic module for energizing and de-energizing the coil for latching and de-latching the moving contact member and the fixed contact member, wherein the electronic module cuts the power to de-energize the coil when the permanent magnet with the retainers holds the moving contact member and the fixed contact member at the latched position.
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