Claims:1. An antitheft system for a three-phase motor, comprising:
antitheft circuit module connected to said three-phase motor to prevent theft of said motor, wherein said antitheft circuit module comprising:
at least one controller means configured to generate ON or OFF command based on an input to start or stop said motor;
at least one oscillator means operably coupled to said controller means and adapted to generate sinusoidal wave signals at high frequency rate and low frequency rate respectively;
wherein, at said low frequency rate, a phase difference is measured between said sinusoidal wave signals and measured signal, and at high frequency rate, an amplitude is measured at resistance, R2;
a power source means includes a main supply and a power supply, wherein said main supply adapted to provide power to said motor and said power supply adapted to provide power to said antitheft circuit module in presence of said mains supply;
a Global System for Mobile communication (GSM) module operably coupled to said controller means to provide alarm to an authorized user;
wherein, in an event, if an unauthorized user removes said motor, then said phase difference measure at low frequency rate changes;
wherein, in an event, if said motor is short circuited, then impedance offered by said motor and a power factor capacitor (C2, C3, C4) is measured as zero and voltage drop is measured at resistance, R1; and
said controller means configured to detect said event and thereby alarm an authorized user using said GSM module about theft and/or short circuit of said motor.
2. The antitheft system as claimed in claim 1, further comprising at least one antitheft relay connected to said motor and is in normally-open position when said motor is in ON state in presence of a main supply, and said relay is in normally-closed position when said motor is in OFF state in presence of a main supply or in absence of said main supply.
3. The antitheft system as claimed in claim 1, further comprising a push pull amplifier connected to increase said motor current so that sufficient voltage drop is measured at said resistance R1.

4. The antitheft system as claimed in claim 1, further comprising: a battery to provide a DC voltage to said controller module when said mains supply is absent.

5. The system as claimed in claim 1, wherein said oscillator means generates sinusoidal wave signals at low frequency, preferably at 50Hz, and at high frequency, preferably at 1 KHz.

6. The system as claimed in claim 3, wherein said resistance R1 is adapted to measure final output voltage.

7. A method for prevent a theft of a three-phase motor by using a system as claimed in claims 1 to 6, wherein said method comprising:
detecting, by using a controller means, said motor is in ON state or OFF state;
generating, by an oscillator means, sinusoidal wave signals at high frequency rate and low frequency rate respectively, wherein at said low frequency rate, a phase difference is measured between said sinusoidal wave signals and measured signal by using a capacitor, C1, and at high frequency rate, an amplitude is measured at resistance, R2;
detecting, by using said controller means, an event of removal of said motor, by measuring change in said phase difference between said sinusoidal wave signals and measured signal;
detecting, by using said controller means, an event of short circuit of said motor, by measuring zero impedance offered by said motor and a power factor capacitor (C2, C3, C4) and voltage drop at resistance, R1, and thereby;
alarming, by said controller means, an authorized user using a GSM module about theft of said motor and/or short circuit of said motor.
, Description:TECHNICAL FIELD OF THE INVENTION

[001] The present subject matter described herein, in general, relates to anti-theft systems and detection circuit for motor disconnection, and more particularly relates to identifying and alarming an authorized user in case of a motor theft.

BACKGROUND OF THE INVENTION

[002] Normally in farms the motor pumps and starter are placed at a greater distance and the distance between the motor and the starter is of the order 700 feet’s, also there are frequent power cuts in rural areas. Due to these reasons there are cases where the pumps gets stolen and the farmer has to bear the cost of buying new pumps, moreover the crop doesn’t get water at the right time.

[003] Thus, there is a need to design an anti-theft system which identifies and gives alarm to the user in case of theft of the motor and provides protection against voltage unbalance. Phase loss, phase reversal etc. at the same time by alerting the users, especially those in rural areas where motors are placed at a greater distance. Further, the GSM based 3 phase motor starter provides the following protection that may include but not limited to: Single phase protection, Voltage Unbalance, under current protection, Phase reversal and phase loss. The user can also turn ON/OFF the motor using GSM (Global system for mobile) mobile phone using SMS (short message service) and IVRS (Interactive Voice Response System).

[004] For some existing anti-theft systems, reference is made to US7880612B2, which relates to anti-theft systems to prevent metal theft from irrigation systems .The alarm device is attached to a plurality of electric conductors such as copper wiring which detects voltage in the irrigation system circuit and if there is no voltage signal from the irrigation system circuit ,then the alarm device automatically breaks the original circuit and inserts itself into the irrigation system circuit .This document teaches that a low voltage signal is injected into the wiring of the electrical conductors when the mains supply is not present , so that when someone tries to break the wire, the output voltage drops to zero and an alarm is given to the user indicating breach of security

[005] Reference is further made to US20150042809A1, which relates to an anti-theft system for vending machine which includes infrared sensors, an alarm device and a processing unit .The infrared sensor, is located at the product exit port of the vending machine and is turned OFF during transaction completion. Once the transaction is completed, the infrared sensor is turned ON, so if someone tries to take some product out from the vending machine, then the infrared sensor gives some output to the controller, whereby the controller gives alarm to the siren.

[006] Reference is made to US20070152820A1, which relates to anti-theft systems for portable computers which include switch detecting portions including a first switch and a second switch, a controller and a button for enabling alarm system. The user has to press a key from the keyboard to activate the alarm , so when the person tries to steal the portable computer then the switches gets released and a signal is given to the controller which then generates a command to the audio processor to generate an alarm using a speaker

[007] Further, reference is also made to Non Patent Reference http://spaceage-security.com/mobile-based-starter.html” entitle ‘Mobile based starter’ which relates to a system that can be used with water pumps ,Industrial motors, AC etc which performs various functions by sending SMS to START/STOP motor, get status of motor appliance etc. and can be controlled by only by authorized personnel –up to 4 users

[008] Referring to Non Patent Document entitled ‘Motor protection circuit breaker or MPCB’ which relates to a motor protection circuit breaker which is a specialized electromechanical device that can be used with motor circuits of both 60 Hz or 50 Hz and which protects against electrical faults like short circuits , motor overload , phase unbalance and phase loss .

[009] Reference is made to Non Patent document “Three phase motor control using GSM” by Prof. R.R Jadhav, et al., which relates to development of mobile phones as remote control applications for the induction motor pumps used in agriculture which is carried out by exchanging information between the user phone and GSM in the form of messages

[0010] However, none of the prior art as discussed above provides a system which provides protection against theft and additionally provide an anti-theft system for motor pumps that detects whether the motor is stolen or not and alerts the user for the same.

[001] Thus, there exists a dire need to provide an anti-theft system which detects whether the motor is stolen or not and accordingly alerts the users by an anti-theft alarm system. Some specific features desirable for the anti-theft alarming system may include, the detection of voltage unbalance, phase loss, under current protection and alarm to the user in case someone tries to switch off the mains supply.

SUMMARY OF THE INVENTION

[002] The following presents a simplified summary of the invention in order to provide a basic understanding of some aspects of the invention. This summary is not an extensive overview of the present invention. It is not intended to identify the key/critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concept of the invention in a simplified form as a prelude to a more detailed description of the invention presented later.

[003] An object of the present invention is to provide an anti-theft system which is configured to detect when the motor is being stolen and short circuited and accordingly alerts the authorized user using a Global System for Mobile communication (GSM) module.

[004] Another object of the present invention is to provide an anti-theft protection system which alerts the authorized user in case an authorized used tries to switch OFF the mains supply.

[005] Yet another object of the present invention is to provide an anti-theft protection system which is capable to detect if someone tries to remove the wire or short the terminals of the motor.

[006] Another object of the present invention is to provide an anti-theft circuit module which provides protection in manual mode (until the user presses the ON button) and auto mode (until the delay time is passed).

[007] Still another object of the present invention is to provide a circuit that does not depend on the contactor auxiliary block so that if someone tries to manipulate the auxiliary block, the anti-theft circuit module does not get compromised.

[008] Accordingly to one aspect, the present invention provides an antitheft system for a three-phase motor, comprising:
antitheft circuit module connected to said three-phase motor to prevent theft of said motor, wherein said antitheft circuit module comprising:
at least one controller means configured to generate ON or OFF command based on an input to start or stop said motor;
at least one oscillator means operably coupled to said controller means and adapted to generate sinusoidal wave signals at high frequency rate and low frequency rate respectively;
wherein, at said low frequency rate, a phase difference is measured between said sinusoidal wave signals and measured signal, and at high frequency rate, an amplitude is measured at resistance, R2;
a power source means includes a main supply and a power supply, wherein said main supply adapted to provide power to said motor and said power supply adapted to provide power to said antitheft circuit module in presence of said mains supply;
a Global System for Mobile communication (GSM) module operably coupled to said controller means to provide alarm to an authorized user;
wherein, in an event, if an unauthorized user removes said motor, then said phase difference measure at low frequency rate changes; and
wherein, in an event, if said motor is short circuited, then impedance offered by said motor and a power factor capacitor (C2, C3, C4) is measured as zero and voltage drop is measured at resistance, R1; and
said controller means configured to detect said event respectively and thereby alarm an authorized user using said GSM module about theft and/or short circuit of said motor.
[009] In another aspect, there is provided a method for prevent a theft of a three-phase motor by using a system as mentioned above, wherein said method comprising:
• detecting, by using a controller means, said motor is in ON state or OFF state;
• generating, by an oscillator means, sinusoidal wave signals at high frequency rate and low frequency rate respectively, wherein at said low frequency rate, a phase difference is measured between said sinusoidal wave signals and measured signal by using a capacitor, C1, and at high frequency rate, an amplitude is measured at resistance, R2;
• detecting, by using said controller means, an event of removal of said motor, by measuring change in said phase difference between said sinusoidal wave signals and measured signal;
• detecting, by using said controller means, an event of short circuit of said motor, by measuring zero impedance offered by said motor and a power factor capacitor (C2, C3, C4) and voltage drop at resistance, R1, and thereby;
• alarming, by said controller means, an authorized user using a GSM module about theft of said motor and/or short circuit of said motor.

[0010] Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which, taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

[0011] The above and other aspects, features, and advantages of certain exemplary embodiments of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which:

[0012] Figure 1 illustrates the circuit diagram of anti-theft circuit for 3 phase motor, according to one embodiment of the present invention.

[0013] Persons skilled in the art will appreciate that elements in the figures are illustrated for simplicity and clarity and may have not been drawn to scale. For example, the dimensions of some of the elements in the figure may be exaggerated relative to other elements to help to improve understanding of various exemplary embodiments of the present disclosure. Throughout the drawings, it should be noted that like reference numbers are used to depict the same or similar elements, features, and structures.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

[0014] The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary.

[0015] Accordingly, those of ordinary skill in the art will recognize that various changes and modifications of the embodiments described herein can be made without departing from the scope of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.

[0016] The terms and words used in the following description and claims are not limited to the bibliographical meanings, but, are merely used by the inventor to enable a clear and consistent understanding of the invention. Accordingly, it should be apparent to those skilled in the art that the following description of exemplary embodiments of the present invention are provided for illustration purpose only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0017] It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.

[0018] By the term “substantially” it is meant that the recited characteristic, parameter, or value need not be achieved exactly, but that deviations or variations, including for example, tolerances, measurement error, measurement accuracy limitations and other factors known to those of skill in the art, may occur in amounts that do not preclude the effect the characteristic was intended to provide.

[0019] Features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.

[0020] It should be emphasized that the term “comprises/comprising” when used in this specification is taken to specify the presence of stated features, integers, steps or components but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0021] In one implementation, referring to figure 1, there is an anti-theft system for a 3 phase motor starter which detects whether the motor is stolen or not and in case if the motor is stolen an authorized user receives a notification using a GSM module. The circuit detects whether the motor is stolen or someone had tried to short the motor and tried removing the motor .This detection is done by injecting two sine wave signals with different frequencies such as:
• At low frequency (preferably at 50 Hz) : the system checks whether the motor is removed
• At high frequency (1 KHz): the system checks whether an unauthorized user tries to short the motor.

[0022] In one implementation, the authorized user receives a notification on an electronic device using a GSM module through short messaging service (SMS) and Interactive voice response system (IVRS). The electronic device may include mobile phone, smart phone, tablet, and the like, which is communicably connected to the anti-theft system using the GSM module.

[0023] In one implementation, as shown in figure 1, there is provided components of the circuit diagram of anti-theft system such as:
(1) a power supply block which provides DC voltage to the controller when the Mains RYB supply is present;
(2) A battery: which delivers power to the controller and other blocks when the mains supply is not present;
(3) A push-pull amplifier: to increase the current required by the system so that a sufficient voltage is measured at Resistance R1;
(4) Resistance, R1: which is used to measure the final output voltage;
(5) Capacitance, C1: to introduce phase shift and to drop the voltage if suddenly a main voltage is present at the antitheft inputs;
(6) Resistance, R2 and R3: to create a ladder network so that the circuit is completed in order for the current to flow; and
(7) C2, C3, C4 are the power factor improvement capacitors.

[0024] In one implementation, there are two modes of operation of a circuit diagram of anti-theft circuit for 3 phase motor, which are as follows:

Mode 1 (Main Supply present): In this mode, there are two cases:
Case (A) when the motor is in OFF state: the motor is either in manual mode or auto mode. In case of manual mode, after the delay timer elapses, the controller waits for the user to press the start button and until the user presses the start button the motor will be subjected to get stolen. The anti-theft relay is in normally closed position and anti-theft circuit module may be connected to protect the motor from being stolen. The relay provides a close path for the sinusoidal signal generated after Push-pull circuit through said motor.
Case (B) when the motor is ON state: in this case the motor may be running and the main contractor can be in ON state .The anti-theft relay will be turned ON and the anti-theft circuit is not connected to the motor. In case when the motor is running and an unauthorized user tries to steal the motor, then the motor current will be zero. Current transformers can be used in the motor starter to sense the current flowing and provide protection against single phase protection,, Dry run prevention and the like. As the current goes to zero, even if the controller has not provided any stop commands and the user has not pressed any stop button still an alarm is given to the user through SMS and IVRS using the GSM module.
Mode 2 (Main Supply Absent): In this mode, the main contactor will be open and the antitheft relay will be in closed condition and the anti-theft circuit may be connected to the motor. As the main supply is not present, a separate rechargeable battery may be connected to the system and it supplies the entire current required for its operation.

[0025] In one implementation, different modes of anti-theft operations have been described as follows.
Mode 1: Motor connected: In this mode the oscillator generates two sine wave signals at frequency 50 Hz and 1 KHz. When the oscillator generates 50 Hz, due to the presence of C1, L (motor) and power factor improvement capacitors, there is a phase difference which can be measured at R1.and the phase difference between the injected sine wave and measured signal will be measured at 75 degree. When the oscillator generates 1 KHz, the amplitude will be measured at resistance, R2 which may be 550 mV as the impedance offered by C1 is lower.

Mode 2: Motor removed: when an unauthorized user tries to remove the motor, then phase difference between the injected signal and the measured signal of 50 Hz may change to 90 degree. Once this malfunction is found, the controller will injects the same signal three times to verify the output and based on this the authorized user will be alarmed by SMS or IVRS using GSM module.

Mode 3: Motor short circuited: when the motor is short circuited, the impedance offered by the LC circuit will be zero and the voltage drop at R1 will be measured as 570 mV. When this change is detected the controller will inject the same signal three times to verify the output and based on this the user will be alarmed by SMS or IVRS using the GSM module.

Mode 4: when the unauthorized user tries to manipulate the main contactor position: As the contactor doesn’t turn ON and OFF the anti-theft system mechanically, the anti-theft system will remain the same. Also the battery is positioned at a place inside the system where user is not able to identify it easily.

[0026] Some of the noteworthy features of the present invention, are as follows:
• In the present invention, there is provided a circuit which is capable of detecting if unauthorized user tries to remove the wire or short the terminals of the motor
• In the present invention, there is provided a circuit which does not depend on the contactor auxiliary block, so even if unauthorized user tries to manipulate or by pass the aux block the circuit is not compromised.
• The present invention provides anti-theft protection both in manual mode and auto mode.
• The present invention provides anti-theft protection if unauthorized user tries to switch OFF the mains supply.
• The present invention provides an anti-theft system that alarms the authorized user by SMS or IVRS using the GSM module

[0027] Some of the advantages of the present invention, are as follows:
• The GSM based 3 phase motor starter of the present invention provides protection against single phase protection, voltage unbalance, under current protection, phase reversal and phase loss.
• The user is alarmed about the theft and/or short circuit of the motor using GSM module through short messaging service (SMS) and Interactive voice response system (IVRS).
• The present invention provides a detection circuit or an anti-theft system which detects when the motor is stolen and accordingly alerts the user by SMS or IVRS using GSM

[0028] Although the antitheft system for a three-phase motor and a method thereof have been described in language specific to structural features and/or methods, it is to be understood that the embodiments disclosed in the above section are not necessarily limited to the specific features or methods or devices described. Rather, the specific features are disclosed as examples of implementations of the antitheft system for a three-phase motor and a method thereof.