CLIAMS:We Claim:-

1. A star delta starter for starting a three phase induction motor comprising a star delta changer (24) housed with a star and delta position of three phase induction motor, a main contactor (23) of electrical air break type for supplying AC power to said star and delta position, a timer control with a logic circuit for controlling AC power supply switching operation for said star and delta position, an overload relay, a push button to initiate and stopping operation of said star delta starter; and a selector switch for selecting fully automatic mode or semi automatic mode or direct online mode to execute star-delta operation of star delta starter;

wherein said star delta changer (24) consists of a coil wounded front magnet (6) with a front magnet coil connection (30), a coil wounded rear magnet (7) with a rear magnet coil connection (31) being positioned on the rear side of said front magnet (6), a star delta changer contact career (2) with terminals of star delta changer contact S1, S2 and S3 being movably secured at the front end of said front magnet (6) along, an axis (16) along which said star delta changer contact career (2) moves; and a spring attachment (18) being mounted at the rear end of said star delta starter behind the rear magnet (7);

wherein said main contactor (23) being positioned at rear side of said star delta changer (24) consists of two fixed contacts (D1, D2, D3 and H1, H2, H3) and moving contacts M1, M2 and M3 for supplying AC power to said front magnet coil connection (30) as well as back magnet coil connection (31); a top cover (9) covering said fixed and moving contacts; a base (14) holding said fixed and moving contacts and consisting of a coil wounded magnet (12) below said fixed and moving contacts; and a horizontal spacing slot (17) for connecting said star delta changer contact career (2) with main contactor (23).

2. The star delta starter (29) as claimed in claim 1, wherein the timer controller controls switching of AC power supply between the front magnet coil connection (30) and rear magnet coil connection (31) through said logic circuit.

3. An operation of a star delta starter comprises a star delta changer (24), a main contactor (23), a timer, an overload relay, a push button and a selector switch for starting a three phase induction motor comprising following steps:
(a) switching “ON" the main contactor (23) and the timer controller for supplying AC power to three terminals of moving contacts M1, M2 and M3 of the main contactor (23);
(b) operating said timer controller to supply AC power to a front magnet coil connection (30) of a front magnet (6) of the star delta changer (24) and thereby switching “ON” said front magnet (6);
(c) connecting terminals of said moving contacts M1, M2 and M3 with fixed contact terminals D1, D2 andD3 of star delta changer (24) through entering a star delta changer contacts career (2) into a space (17) by means of the motion of an axis (16) towards the main contactor (23) and connecting fixed contacts terminals H1, H2 and H3 with star delta changer contacts terminals S1, S2 and S3 (which is internally connected with conductive part (22) of said star delta changer contacts career (2))for completing the star circuit and thereby starting said three phase induction motor in star position;
(d) cutting the power of the front magnet (6) of the star delta changer (24), after the pre set time i.e. 10 seconds, by the logic control circuit of the timer and supplying the power to a back magnet (7) of a star delta changer (24) for completing the delta circuit by connecting the moving contacts terminals M1, M2 and M3 with the fixed contacts terminals H1, H2 and H3, and thereby running the three phase induction motor in delta position;
(e) moving back the axis (16) of the star delta changer (24) for discharging the star delta changer contacts career (2) from the space (17) of the main contactor (23);
(f) cutting the power of the back magnet (7) by the logic control circuit after a predetermined time interval and thereby bringing the three phase induction motor in “OFF” position.

4. The operation of the star delta starter for starting a three phase induction motor as claimed in claim 3, wherein switching of AC power supply between the front magnet coil connection (30) and rear magnet coil connection (31) is controlled by the timer controller through said logic circuit.

Dated this 24th day of December 2012.

,TagSPECI:FORM 2
THE PATENT ACT 1970
(39 of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION: STAR DELTA STARTER

2. APPLICANT:

1. (a) NAME : ANAM ATUL HARESHBHAI
(b) NATIONALITY: India
(c) ADDRESS : 130, OHDAV RESIDENCY,
PRAMUKHSWAMI NAGAR ROAD,
BHUJ – KUTCH. 370001

3. PREAMBLE TO THE DESCRIPTION
PROVISIONAL

The following specification describes the invention. þ COMPLETE

The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF THE INVENTION

The present invention relates to an induction motor starter, particularly a star delta starter comprising an improved component called star delta changer that reduces the size, cost and maintenance of the star delta starter by replacing star contactor and delta contactor in it and gives efficient result.

BACK GROUND AND PRIOR ART OF THE INVENTION

Induction motors are started directly through on line in general, but when large size motors are started in that way, they cause disturbance in voltage supply due to maximum starting current rush. To limit the starting current rush, large induction motors are required to start at reduced voltage initially and then allowed to have full supply voltage when they come up to its full running speed.
Star delta starters are used for starting large induction motors at reduced voltage. While starting the motor, windings are connected in star configuration and this reduces the voltage across each winding. This also reduces the torque by a factor of three. After a period of time the winding are reconfigured as delta and the motor runs normally.

Such an induction motor starter is known from US 2005/0017592 bearing the title “Rotary Electric Machine Having Armature Winding Connected in Delta-Star Connection” discloses a combination of a delta-winding and a star-winding in connection with the armature winding. The delta-star winding includes turn-ratio changing means for changing a turn-ratio of the delta-winding to the star-winding in which a turn ratio of the delta-winding to the star-winding is easily changed and a length of lead wires is shortened. The delta-star winding is a combination of a delta-winding connected in a delta-connection and a star-winding connected in a star-connection. It also explains that the delta-winding is composed of first three phase windings and the star-winding is composed of second three phase windings. A pair of the delta-star windings may be wound in the same armature core and connected in parallel to each other to increase a current capacity of the armature.

401/BOM/1974 bearing the title of “An Improved Star-Delta Starter for 3-Phase Induction Motor” discloses an improved star-delta starter for 3-phase induction motor comprising an electromagnetic main switching device having a coil connectable to a power input and at least three main normally open contacts adapted to close the power input phase lines connectable to one set of terminals of the motor when said main switching device is energized. Said star-delta starter further comprises a resistor in series with the coil of the said programme switching device and the main switching device may be provided with another auxiliary normally closed contact connected across said resistor.

PCT/RU2000/000492 discloses a combination of star and delta winding in a combined electrical machine windings, fed with three phase current. In which the combination of star and delta winding results reduction of load currents of the windings. The arrangement of the combination of star and delta windings explains that one part of said winding is connected in a star and the other part is connected in a delta with a spatial shift between these parts.

Although the above described starters have disclosed the combination of star contactor and delta contactor still they leave the scope for improvement to provide easy, cost effective, smaller size, comfort, maintenance free and user friendly device for starting induction motors and the present innovative device and method does as such so and overcomes all the aforesaid disadvantages associated with the prior arts.

OBJECT OF THE INVENTION

The main object of this invention is to provide a star delta starter for starting an induction motor without high inrush current and high torque.

Further object of the invention is to provide a star delta starter having fewer components.

Another object of this invention is to provide a star delta starter that reduces cost, maintenance and size up to 50% by providing a single star delta changer part rather than providing two individual star and delta contactors part

Yet another object of this invention is to provide a star delta starter that can be used as a direct online (D.O.L) starter.

Still another object of this invention is to provide a star delta starter that can be easily installed.

SUMMARY OF THE INVENTION

The present invention relates to an induction motor starter, particularly a star delta starter comprising a main contactor that acts as an electrical air-break contactor for supplying AC power to star position and delta position of the three phase induction motor a timer control with a logic circuit for controlling AC power supply switching operation for star position and delta position and for adjusting a time delay of switching over to delta position from a star position; a star delta changer housed with a star and delta position each of which being magnetically operated with said timer control operation; an overload relay for protecting motor from overload; a push button to initiate starting and stopping operation of star delta starter; and a selector switch for selecting fully automatic mode or semi automatic mode or direct online mode to execute star-delta operation of star delta starter. The whole system or apparatus is functioned with the help of automatic control mechanism, for the purpose of starting the three phase induction motor.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 explains the isometric view (partly cut way) of main contactor and star-delta changer.

Fig. 2 explains the isometric internal view of main contactor.

Fig. 3 explains the side view of main contactor and star delta changer in on (star) position.

Fig. 4 explains the isometric view of main contactor and star delta changer in on (delta) position.

Fig. 5 explains the top view of contacts of star-delta changer.

Fig. 6 explains the side view of contacts of star-delta changer.

Fig. 7 explains the wiring of automatic star-delta starter in off position.

Fig. 8 explains the wiring of automatic star-delta starter in on (star) position.

Fig. 9 explains the wiring of automatic star-delta starter in on (delta) position.

Fig. 10 explains the wiring of control circuit.

DETAIL DESCRIPTION OF THE INVENTION

Before explaining the present invention in detail, it is to be understood that the invention is not limited in its application to the details of the construction and arrangement of parts illustrated in the accompanying drawings. The invention is capable of other embodiments, as depicted in different figures as described above and of being practiced or carried out in a variety of ways. It is to be understood that the phraseology and terminology employed herein is for the purpose of description and not of limitation.

As directed in Fig. 1, a star delta starter for starting a three phase induction motor comprises a star delta changer (24) of substantially cylindrical shaped housed with a star and delta position of three phase induction motor, a main contactor (23) of electrical air-break type for supplying AC power to said star position and delta position, a timer control with a logic circuit for controlling AC power supply switching operation for star position and delta position and for adjusting a time delay of switching over to delta position from a star position; an overload relay for protecting motor from overload; a push button to initiate starting and stopping operation of star delta starter; and a selector switch for selecting fully automatic mode or semi automatic mode or direct online mode to execute star-delta operation of star delta starter.

Said star delta changer consists of a coil wounded front magnet (6) with a front magnet coil connection (30), a coil wounded rear magnet (7) with a rear magnet coil connection (31) being positioned on the rear side of said front magnet (6), a star delta changer contact career (2) with terminals of star delta changer contact S1, S2 and S3 being movably secured at the front end of said front magnet; an axis (16) along which said star delta changer contact career (2) moves; and a spring attachment (18) being mounted at the rear end of said star delta starter behind the rear magnet (7) to expel or urge the axis (16) of the star delta changer contact career (2) ahead as directed in Fig. 3 as well as to pull back the axis (16) of the star delta changer contact career (2) to its original position as directed in Fig. 1, during the operation. If the front magnet (6) is in ‘ON’ position, the star delta starter works in star position and if the back magnet is in ‘ON’ position, the star delta starter (29) works in delta position. ‘ON’ and ‘OFF condition of the front and rear magnet depends on AC power supply to its corresponding magnet coil connection (30) and (31) respectively. Switching of AC power supply between the front magnet coil connection (30) and rear magnet coil connection (31) is controlled by the timer controller.

The star delta changer contacts career (2) consists of three terminals of star delta contacts namely S1, S2 and S3 (as explained earlier) to connectably engage with the terminals of fixed contact H1, H2 and H3 of the main contactor (23) and each of said star delta contacts, as directed in Fig. 5 and 6, has two parts namely an upper non conductive part (19) and a lower conductive part (22).

Said main contactor (23) being positioned at rear side of said star delta changer (24) consists of two fixed contacts (D1, D2, D3 and H1, H2, H3) and moving contacts (M1, M2, M3), as directed in Fig.2, for supplying AC power to said front magnet coil connection (30) as well as back magnet coil connection (31) with the help of the timer control; a top cover (9) covering said fixed and moving contacts; a base (14) holding said fixed and moving contacts and consisting of a coil wounded magnet (12) below said fixed and moving contacts; and a horizontal spacing slot (17) for connecting said star delta changer contact career (2) with main contactor (23), as directed in Fig. 3 & 4.

As directed in Fig. 7, a main three phase AC power supply (L1, L2 and L3) is directly applied to each terminals of the moving contacts M1, M2 and M3 of the main contactor (23) and the movement or operation of said moving contacts is controlled by relay operated time controller. U1, V1 and W1 terminals of three phase induction motor is connected to the terminals of the fixed contacts D1, D2 and D3 of main contactor (23) and whereas, U2, V2 and W2 terminals of three phase induction motor is connected to the terminals of the fixed contacts H1, H2 and H3 of the main contactor (23).

In operation, initially in the “OFF” position, terminals of fixed contacts H1, H2, H3 and D1, D2, D3 as well as terminals of moving contacts M1, M2, M3 and the terminals of star delta changer contacts S1, S2 and S3 are normally opened. To start the functions of the star delta starter of three phase induction motor, the main contactor (23) is switched “ON”. Along with the main contactor (23) the front magnet (6) is also switched “ON” by means of the timer control operation. In “ON” position, the terminals of the moving contacts M1, M2 and M3 are connected with the terminals of the fixed contacts D1, D2 and D3, as directed in Fig. 8 through entering the star delta changer contacts career (2) into the space (17) by means of the motion of the axis (16) towards the main contactor (23), as directed in Fig. 3, and at the same time the terminals of the fixed contacts H1, H2 and H3 are not connected with the terminals of the moving contacts M1, M2 and M3 as the star delta changer contacts career (2) has the non conductive part (19) towards the terminals of the moving contacts M1, M2 and M3. The terminals of fixed contacts H1, H2 and H3 are connected with the terminals of the star delta changer contacts S1, S2 and S3 (which is internally connected with the conductive part (22) of star delta changer contacts career (2)), and the star circuit is completed, as directed in Fig. 8. Hence, the three phase induction motor is started in a star position.

After the pre set time i.e. 10 seconds by the timer, the power of the front magnet (6) of the star delta changer (24) is cut by the logic control circuit of the timer and the power is supplied to the back magnet (7) of the star delta changer (24), thus the back magnet (7) is switched “ON”, the terminals of the moving contacts M1, M2 and M3 are connected with the terminals of the fixed contacts H1, H2 and H3, and the delta circuit is completed, as directed in Fig. 9. Hence, the three phase induction motor works in delta position at runs in its full speed. In load position, the axis (16) of the star delta changer (24) is moved back and the star delta changer contacts career (2) is discharged from the space (17). After few seconds the power of the back magnet (7) is also cut by the logic control circuit of the timer.

As directed in Fig. 10, said logic control circuit of the timer maintains smooth and automatic functioning of the three phase induction motor with time delay of few seconds for star to delta changeover with main contactor (23) and the star delta changer (24), wherein either of the main contactor (23) and star delta changer (24) works in load. In direct online position, the star delta starter works without any wiring and other changes. The timer and star delta changer (24) stop to work; and the main contactor (23) and overload relay work as it is in the direct online position.

While, the invention has been described with respect to the given embodiment, it will be appreciated that many variations, modifications and other applications of the invention may be made. However, it is to be expressly understood that such modifications and adaptations are within the scope of the present invention, as set forth in the following claims.

We Claim:-

1. A star delta starter for starting a three phase induction motor comprising a star delta changer (24) housed with a star and delta position of three phase induction motor, a main contactor (23) of electrical air break type for supplying AC power to said star and delta position, a timer control with a logic circuit for controlling AC power supply switching operation for said star and delta position, an overload relay, a push button to initiate and stopping operation of said star delta starter; and a selector switch for selecting fully automatic mode or semi automatic mode or direct online mode to execute star-delta operation of star delta starter;

wherein said star delta changer (24) consists of a coil wounded front magnet (6) with a front magnet coil connection (30), a coil wounded rear magnet (7) with a rear magnet coil connection (31) being positioned on the rear side of said front magnet (6), a star delta changer contact career (2) with terminals of star delta changer contact S1, S2 and S3 being movably secured at the front end of said front magnet (6) along, an axis (16) along which said star delta changer contact career (2) moves; and a spring attachment (18) being mounted at the rear end of said star delta starter behind the rear magnet (7);

wherein said main contactor (23) being positioned at rear side of said star delta changer (24) consists of two fixed contacts (D1, D2, D3 and H1, H2, H3) and moving contacts M1, M2 and M3 for supplying AC power to said front magnet coil connection (30) as well as back magnet coil connection (31); a top cover (9) covering said fixed and moving contacts; a base (14) holding said fixed and moving contacts and consisting of a coil wounded magnet (12) below said fixed and moving contacts; and a horizontal spacing slot (17) for connecting said star delta changer contact career (2) with main contactor (23).

2. The star delta starter (29) as claimed in claim 1, wherein the timer controller controls switching of AC power supply between the front magnet coil connection (30) and rear magnet coil connection (31) through said logic circuit.

3. An operation of a star delta starter comprises a star delta changer (24), a main contactor (23), a timer, an overload relay, a push button and a selector switch for starting a three phase induction motor comprising following steps:
(a) switching “ON" the main contactor (23) and the timer controller for supplying AC power to three terminals of moving contacts M1, M2 and M3 of the main contactor (23);
(b) operating said timer controller to supply AC power to a front magnet coil connection (30) of a front magnet (6) of the star delta changer (24) and thereby switching “ON” said front magnet (6);
(c) connecting terminals of said moving contacts M1, M2 and M3 with fixed contact terminals D1, D2 andD3 of star delta changer (24) through entering a star delta changer contacts career (2) into a space (17) by means of the motion of an axis (16) towards the main contactor (23) and connecting fixed contacts terminals H1, H2 and H3 with star delta changer contacts terminals S1, S2 and S3 (which is internally connected with conductive part (22) of said star delta changer contacts career (2))for completing the star circuit and thereby starting said three phase induction motor in star position;
(d) cutting the power of the front magnet (6) of the star delta changer (24), after the pre set time i.e. 10 seconds, by the logic control circuit of the timer and supplying the power to a back magnet (7) of a star delta changer (24) for completing the delta circuit by connecting the moving contacts terminals M1, M2 and M3 with the fixed contacts terminals H1, H2 and H3, and thereby running the three phase induction motor in delta position;
(e) moving back the axis (16) of the star delta changer (24) for discharging the star delta changer contacts career (2) from the space (17) of the main contactor (23);
(f) cutting the power of the back magnet (7) by the logic control circuit after a predetermined time interval and thereby bringing the three phase induction motor in “OFF” position.

4. The operation of the star delta starter for starting a three phase induction motor as claimed in claim 3, wherein switching of AC power supply between the front magnet coil connection (30) and rear magnet coil connection (31) is controlled by the timer controller through said logic circuit.

Dated this 24th day of December 2012.

Abstract
The present invention relates to an induction motor starter, particularly a star delta starter comprising an improved component called star delta changer that reduces the size, cost and maintenance of the star delta starter by replacing conventional two separate star contactor and delta contactor in it and gives efficient result. The use of star delta changer in the induction motor starter reduces the number of components, cost up to 50%, maintenance up to 50% and size up to 50% as compared to the existing motor starters. The improved motor starter can also be used as Direct On-Line (D.O.L) Starter and the installation of said motor starter is very easy.