Claims:1. A circuit arrangement for detecting motor disconnection, said arrangement comprising:
resistors R1, R2 and R3 operatively connected inbetween a push pull amplifier and an antitheft relay;
wherein the push pull amplifier is operatively controlled by a controller powered by a main supply;
capacitors C1, C2, C3 and C4 operatively connected to the motor by means of a capacitor switching contactor;
wherein said resistor R1 is adapted to measure final output voltage, and resistors R2, R3 complete the circuit;
wherein said capacitor C1 operatively introduces phase shift and to drop the voltage;
wherein said capacitors C2, C3 and C4 are power factor improvement capacitors;
wherein the push-pull amplifier operatively increases current in the circuit; characterized by a significant drop in voltage across resistor R2.

2. The arrangement as claimed in claim 1, wherein the drop in voltage across the resistor R2 is zero.

3. The arrangement as claimed in claim 2, wherein the arrangement is open circuited and no current flows through.

4. The arrangement as claimed in claim 1, wherein an oscillator generating sine wave signals at 1 KHz is operatively connected between the controller and push pull circuit.

5. The arrangement as claimed in claim 1, wherein a differential amplifier is operatively connected across resistor R1.

7. The arrangement as claimed in claim 5, wherein voltage measured across output of the differential amplifier is 140mV

8. The arrangement as claimed in claim 1, wherein a power supply provides DC voltage to the controller when the main supply is present.

9. The arrangement as claimed in claim 1, wherein a battery delivers power to the controller when the main supply is in off position.

10. The arrangement as claimed in claim 1, wherein the main supply is operatively connected to the controller by a main contactor.

11. The arrangement as claimed in claim 10, wherein the battery is rechargeable.

12. The arrangement as claimed in claim 1, wherein the GSM module sends an SMS or IVRS to a registered mobile number.

13. The arrangement as claimed in claim 7, wherein the push pull amplifier operatively increases the current in the arrangement so as to retain the voltage across R1.

14. The arrangement as claimed in claim 1, wherein C1 operatively introduces phase shift and voltage drop when the main voltage is present at the antitheft relay inputs.

15. The arrangement as claimed in claim 1, wherein R2 and R3 operatively form a ladder network to complete the arrangement.
, Description:FIELD OF THE INVENTION

[001] The subject matter of the present invention, in general, relates to antitheft circuitry and particularly, pertains to a circuit arrangement for identifying and providing alarm to the user in case a motor has been disconnected from an irrigation system.

BACKGROUND OF INVENTION

[002] A wide variety of antitheft devices are known in the art. Demand for improved security of installations made in open spaces has increased, especially in recent years as the number of these devices has grown proportionately. However, despite the momentum of accelerating technological innovation, such antitheft systems have not been widely accepted by the public owing to complicated operation, complicated or unmanageable or unwieldy design that has often lead to such security devices/systems not being effectively used on an everyday basis by the owners.

[003] In some cases, these devices may be of a very simple design, while in other cases, they may be of a more sophisticated and complex design. However, as is well known, these known antitheft devices or systems may be easily defeated by thieves, and especially, by professional thieves and/or have other disadvantages associated with their use. It has been observed that even the most sophisticated antitheft devices may be defeated by an experienced and determined, thief, and that traditional audio/visual alarm systems have drawbacks associated with their use. In case of some recovery devices, their use may be limited by the availability, or lack thereof, of the corresponding tracker or receiver device(s) in the particular locality. Moreover, the conventional antitheft apparatus/devices available in the market are complicated and not very effective; especially the audio-visual alarm systems available are not very useful when the installations are at a considerable distance from the owners.

[004] Normally in farms the distance between the pumps and the starter is substantially very far, and also there are frequent power cuts in rural areas. Due to the above reasons there are cases whether the pump is stolen and the farmer has bear the cost of buying new pumps and also the crops doesn’t get water at the right time.

[005] In the event, a secure protective system that could be made widely available and one that could be properly and effectively implemented without undue effort, difficulty or inconvenience for the owner, might serve to provide a positive contribution towards decreasing the prevalence of theft generally.

[006] Reference is made to US 7880612 B2, wherein a method and an alarm device used to prevent metal theft from irrigation systems is disclosed. The alarm device attaches to a plurality of electric conductor such as copper wiring that is in need of protecting and the pre-existing irrigation system circuit. The alarm device detects voltage in the irrigation system circuit and if there are no voltage signals from the irrigation system circuit, then the alarm device automatically breaks the original circuit and inserts itself into the irrigation system circuit. The alarm device then sends a low voltage, low current down the plurality of electric conductors and the plurality of conductors then become part of a circuit that energizes a magnetic switch located in the alarm device. A breach of integrity of the plurality of conductors such as by physical detachment triggers an alarm condition which lead to audio and visual alarms plus activating an automated dialer. It injects a low voltage signal into the wiring of the electrical conductors when the mains supply is not presents. 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. The drawback of the said document being that if one shorts the wire in off condition of the motor, theft is possible as no alarm is generated. The present invention does sway with this drawback.

[007] Further reference is made to US 2015/0042809 A1, wherein antitheft systems for a vending machine are disclosed. The antitheft alarm system for a vending machine includes an infrared sensor, an alarm device, and a processing unit. When the infrared sensor detects an object passing through a product exit port of the vending machine, the processing unit controls the alarm device to emit an alarm to draw attention to proximate persons around the vending machine. An antitheft alarm method for a vending machine is also disclosed. It employs an infrared sensor located at the product exit port of the vending machine. The infrared sensor 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 an output to the controller. The controller gives an alarm to the siren and also the controller is connected to the NIC (network adapter) and the communicated to the user using LAN or internet. There is also a maintenance mode where the hood sensor gives the command to the controller whether the main door is closed or open for maintenance. As the protection system employs an infra-red sensor, false alarms may be triggered for any object, that may not be a person, that may come inbetween.

[008] Further reference is made to US 2006/022837 A1, wherein a device for detecting line-disconnection in stepping motor driver is disclosed. The device for detecting disconnection for use in a stepping motor driver is provided having a driver circuit which comprises a pair of windings wound in a bifilar turn arrangement; a pair of MOSFETs connected to the other end of each winding ; a common current detecting resistor connected between MOSFETs and ground; a first reference voltage generator for producing a first reference voltage; a second reference voltage generator for producing a second reference voltage lower than first reference voltage; a decision circuit for comparing the detection voltage on current detecting resistor with second reference voltage to produce an alarm signal when detection voltage is higher than second reference voltage; and a disconnection detector for receiving an alarm signal from decision circuit after comparator produces a chopper signal to produce a disconnection signal upon occurrence of line-disconnection in winding. The drawback of the said document being that the DC power supply does not protect the motor if its terminals are shorted. It will not detect the line disconnection since it is shorted by external wire.

[009] Further reference is made to JP 2014/212639, wherein a detector for a drive unit, capable of precisely detecting a disconnection in a motor feeder line is disclosed. A full-bridge circuit is formed from switching elements FET1-FET4 and is connected with a motor 1 through motor feeder lines 4a, 4b. When all the switching elements FET1-FET4 are off, a power supply +V is fed to resistors R1-R4. A first detection voltage VM+ is detected with a division ratio of the resistor R1 to the resistor R2 and a second detection voltage VM- is detected with a division ratio of the resistor R3 to the resistor R4. When an absolute value of a difference between the first detection voltage VM+ and the second detection voltage VM- is equal to or larger than a predetermined value, the motor feeder lines 4a, 4b are determined to be disconnected.

[0010] Further reference is made to US 2011/106469 A1, wherein a circuit and method for detecting a short and a disconnection of a resolver for a Hybrid Electric Vehicle (HEV), which can accurately analyse and detect the fault code of the resolver which detects the speed of a drive motor for an HEV and the angle of a rotator for an HEV is disclosed. The circuit is configured such that resistors for detection of a short/disconnection are connected between output signal terminals of a resolver which are connected to input terminals of an RDC connected to a CPU, and the CPU measures certain voltages, obtained according to voltage division by the resistors for detection of a short/disconnection and pull-up resistors connected between a power source and the output signal terminals, with reference to differential signals which are output signals provided to the RDC through the output signal terminals.

[0011] Further reference is made to JPH 02290191 A, wherein detection of the disconnection of a motor circuit quickly and automatically by a method wherein a detecting resistor is connected in series to a power source and the circuit of a motor being stopped to detect the disconnection in the motor circuit by a voltage detected by the detecting resistor is disclosed. The disconnection check of a motor circuit is affected under a condition that a motor is stopped. When the motor circuit is not disconnected, a detecting resistor is connected to a DC power source through the series circuit of a contact, a motor, and the contact. When there is disconnection, a voltage is not impressed on the detecting resister and a signal whose level is converted by a buffer becomes 'L' level. The existence of the disconnection in the motor or the wiring system thereof can be known by detecting whether the input of a pin is 'H' or 'L' under a condition that the motor is stopped or a relay is excited and the relays are not excited. According to this method, the disconnection of the motor circuit may be detected quickly and automatically.

[0012] While the existing technologies discussed hereinabove discuss antitheft devices and systems in general, their circuits are applicable only to a specific rating of motor and power factor improvement capacitor. As the range is small and it’s specifically tuned to that value, the values of R and C have to be altered to meet the requirements. Thus there is a need to design a system which remains same for any rating of the motor and the power factor improvement capacitor.

[0013] Thus, in view of the drawbacks of hitherto prior art documents, it is realised that there is a dire need for an improved but simple circuit arrangement for detecting motor disconnection which remains same for any rating of the motor and the power factor improvement capacitor.

SUMMARY OF THE INVENTION

[0014] 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.

[0015] An object of the present invention is to provide a circuit arrangement for detecting motor disconnection.

[0016] Another object of the present invention is to detect whether the motor has been stolen or not.

[0017] Another object of the present invention is to provide a circuit arrangement that remains same for any rating of the motor and the power factor improvement capacitor.

[0018] Another object of the present invention is to provide an antitheft circuit arrangement whose detection range is magnified.

[0019] Another object of the present invention is to provide an antitheft circuit arrangement that does away with the need for multiple checks for getting the average readings before generating the alarm.

[0020] Another object of the present invention is to provide antitheft protection even though the mains supply is switched off.

[0021] Another object of the present invention is to provide a circuit arrangement that detects whether the motor is stolen or tried to short the motor and then remove the motor by injecting sine wave signal of high frequency.

[0022] Another object of the present invention is to provide protection in manual mode (until the user presses ON button) and auto mode (until the delay time is elapsed).

[0023] Another object of the present invention is to provide antitheft protection that does not depend on the contactor auxiliary block thereby according protection even though the aux block is compromised.

[0024] Another object of the present invention is to send an SMS or IVRS using GSM to the registered user once it is determined that the motor is stolen.

[0025] Yet another object of the present invention is when the motor is in OFF position, when in manual mode, after the delay timer elapse the controller waits for the user to press the start button. Until the user presses the start button the motor is subjected to get stolen. During such time the antitheft relay is in normally closed position and the antitheft circuit is connected to protect the motor from being stolen. The capacitor switching contactor is in open condition due to which the power factor improvement capacitor gets isolated from the antitheft system.

[0026] Yet another object of the present invention is when the motor is running and the main contactor is in ON state, the antitheft relay is turned on and the antitheft circuit is not connected to the motor. The capacitor switching contactor is turned on and the capacitor comes in parallel with the motor. This capacitor thus helps in improving the power factor in running condition. Now in the running condition if someone tries to steal the motor then the motor current will be zero. A current transformer (not shown in the diagram) is used in the motor starter to sense the current flowing and give following protection: Single phase protection, Dry run prevention. As the current goes to zero even when the controller has not provided any stop command or the user has not pressed the stop button, an alarm is given to the user through SMS and IVRS using GSM.

[0027] Yet another object of the present invention is when the main contactor is open and the antitheft relay is in closed condition, antitheft circuit is connected to the motor and capacitor switching contactor is open and C2, C3 and C4 are disconnected from the system. As the main supply is not present, a separate rechargeable battery is connected to the system and it supplies the entire current required for its operation.

[0028] Yet another object of the present invention is when the motor is connected, the oscillator generates sine wave signals at 1 KHz. Due to high frequency the motor winding offers high impedance. So maximum voltage drop is at the motor winding. The voltage measured at the output of differential amplifier is 140mV.

[0029] Yet another object of the present invention is when the motor is removed, the circuit is open circuited and no current flows and the voltage drop across the resistor R2 is zero. So an alarm is generated with SMS or IVRS using GSM.

[0030] Yet another object of the present invention is when the motor is short, the impedance offered by the LC circuit is zero and the voltage at the output of differential amplifier increases to 1.2V. So an alarm is generated with SMS or IVRS using GSM.

[0031] Accordingly, in one aspect of the present invention, a circuit for detecting motor disconnection is disclosed.

[0032] In another aspect, a circuit that remains same for any rating of the motor and the power factor improvement capacitor is disclosed.

[0033] In another aspect, a circuit that detects whether the motor is stolen or tried to short the motor and then remove the motor by injecting sine wave signal of high frequency is disclosed.

[0034] In another aspect, there is provided an antitheft circuit arrangement that detects whether the motor is stolen or not is disclosed. The circuit detects whether the motor is stolen or someone had tried to short the motor and then tried to remove the motor by injecting sine wave signal of high frequency. During the antitheft operation the power factor improvement capacitor is removed from the system by means of contactor. As the capacitor is removed, only motor impedance comes into picture. As motor winding is only present it offers high impedance to high frequency due to which there is high voltage drop across the winding when the motor is connected. And when someone tries to short the motor, the voltage drop goes to zero; a high voltage is measured at the output of differential amplifier. If the motor is removed, then the circuit is open circuit and no current flows and the voltage is zero at the output of differential amplifier. If the motor is stolen the registered user receives an SMS or IVRS using GSM.

[0035] In another aspect of the present invention, a circuit arrangement for detecting motor disconnection is disclosed. The said arrangement comprising resistors R1, R2 and R3 operatively connected inbetween a push pull amplifier and an antitheft relay; wherein the push pull amplifier is operatively controlled by a controller powered by a main supply; capacitors C1, C2, C3 and C4 operatively connected to the motor by means of a capacitor switching contactor; wherein said resistor R1 is adapted to measure final output voltage, and resistors R2, R3 complete the circuit; wherein said capacitor C1 operatively introduces phase shift and to drop the voltage; wherein said capacitors C2, C3 and C4 are power factor improvement capacitors; wherein the push-pull amplifier operatively increases current in the circuit; characterized by a significant drop in voltage across resistor R2.

[0036] 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

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:

[0037] Figure 1 illustrates circuit diagram of antitheft circuit arrangement for 3-phase motor with contactor switching capacitor according to one implementation of the present invention.
[0038] Figure 2 illustrates a flow chart on the working of the antitheft circuit arrangement when there is theft according to one implementation of the present invention.

[0039] Figure 3 illustrates another flow chart on the working of the antitheft circuit arrangement when the circuit is short according to another implementation of the present invention.

[0040] 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

[0041] 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.

[0042] 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.

[0043] 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.

[0044] It is to be understood that the singular forms “a”, “an”, and “the” include plural referents unless the context clearly dictates otherwise.

[0045] 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.

[0046] 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.

[0047] 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 component but does not preclude the presence or addition of one or more other features, integers, steps, components or groups thereof.

[0048] The subject invention lies in providing a circuit for detecting motor disconnection.

[0049] In the present invention, an antitheft circuit arrangement that detects whether the motor is stolen or not is disclosed. When the motor is stolen the registered user receives an SMS or IVRS using GSM. The circuit can identify the disconnection of the motor by means of continuously injecting the electrical signal and measuring the receiving strength of the electrical signal. Based on the value of the electrical signal, the given arrangement can identify whether motor is disconnected or the motor terminals are shorted together and then disconnected. During the antitheft operation the power factor improvement capacitor is removed from the system by means of contactor. As the capacitor (C) is removed, only motor impedance comes into picture. As motor winding is only present it offers high impedance to high frequency due to which there is high voltage drop across the winding when the motor is connected. And when someone tries to short the motor, the voltage drop goes to zero; a high voltage is measured at the output of differential amplifier. If the motor is removed, then the circuit is open circuit and no current flows and the voltage is zero at the output of differential amplifier.

[0050] In one implementation, a circuit arrangement to detect whether a motor has been stolen or not is provided for.

[0051] In one implementation, an antitheft circuit arrangement that remains same for any rating of the motor and the power factor improvement capacitor is provided for.

[0052] In one implementation, an antitheft circuit arrangement whose detection range is magnified is provided for.

[0053] In one implementation, an antitheft circuit arrangement that does away with the need for multiple checks for getting the average readings before generating the alarm is provided for.

[0054] In one implementation, the antitheft circuit arrangement is operable even though the main supply is switched off is provided for.

[0055] In one implementation, an antitheft circuit arrangement that detects whether the motor is stolen or tried to short the motor and then remove the motor by injecting sine wave signal of high frequency is provided for.

[0056] In one implementation, antitheft protection in manual mode (until the user presses ON button) and auto mode (until the delay time is elapsed) is provided for.

[0057] In one implementation, antitheft protection that does not depend on the contactor auxiliary block is provided for.

[0058] In one implementation, an SMS or IVRS using GSM is sent to the registered user once it is determined that the motor is stolen is provided for.

[0059] Normally in farms the distance between the pumps and the starter is very far, and also there are frequent power cuts in rural areas. Due to the above reasons there are cases whether the pump is stolen and the farmer has bear the cost of buying new pumps and also the crops doesn’t get water at the right time. The purposed solution is an antitheft system which tries to detect when the motor is being stolen and alerts the user by SMS or IVRS using GSM.

[0060] The subject invention relates to an antitheft circuit arrangement that detects whether the motor is stolen or not. In particular, it detects whether the motor is stolen or someone has tried to short the motor and then tried to remove the motor by injecting sine wave signal of high frequency. In case the motor is stolen, the registered user receives an SMS or IVRS using GSM.

[0061] During the antitheft operation the power factor improvement capacitor (c) is removed from the system by means of contactor (15). As the capacitor (c) is removed, only motor (12) impedance comes into picture. As motor winding is only present it offers high impedance to high frequency due to which there is high voltage drop across the winding when the motor (12) is connected. And when someone tries to short the motor (12), the voltage drop goes to zero; a high voltage is measured at the output of differential amplifier (14). If the motor (12) is removed, then the circuit is open circuit and no current flows and the voltage is zero at the output of differential amplifier (14).

[0062] Figure 1 illustrates the circuit diagram of antitheft circuit arrangement for 3 phase motor with contactor switching capacitor. The different modes of operation of the antitheft circuit is as follows:
1. Motor connected: The oscillator generates sine wave signals at 1 KHz. Due to high frequency the motor (12) winding offers high impedance. So maximum voltage drop is at the motor winding. The voltage measured at the output of differential amplifier is 140mV.

2. Motor removed: When somebody tries to remove the motor (12), the circuit is open circuited and no current flows the system and the voltage drop across the resistor R2 is zero. So an alarm is generated with SMS or IVRS using GSM.

3. Motor short: When somebody tries to short the motor (12), then the impedance offered by the LC circuit (L is inductance offered by using the motor) is zero and the voltage at the output of differential amplifier (14) increases to 1.2V. So an alarm is generated with SMS or IVRS using GSM.

[0063] Also there may be a case where someone tries to manipulate the contactor position; in that case as the contactor doesn’t turn on and off the system mechanically, the antitheft system remains the same. Also the battery is positioned at a place inside the system where normal user is not able to detect is easily.

[0064] It has two modes of operation, depending on if the main supply is present or not is as follows:
1. Main Supply Present:
i. Motor OFF: In this case the motor (12) is either in manual mode (until the user presses ON button) or in auto mode (until the delay time is elapsed). In case of manual mode, after the delay timer elapse the controller (5) waits for the user to press the start button. In this case, until the user presses the start button the motor (12) is subjected to get stolen. The antitheft relay (13) is in normally closed position and the antitheft circuit is connected to protect the motor from being stolen. The capacitor switching contactor (15) is in open condition due to which the power factor improvement capacitor gets isolated from the antitheft system.
ii. Motor ON: In this case the motor (12) is running and the main contactor (2) is in ON state. The antitheft relay is turned on and the antitheft circuit is not connected to the motor (12). The capacitor switching contactor (15) is also turned on and the capacitor (C) comes in parallel with the motor (12). This capacitor thus helps in improving the power factor in running condition. Now in the running condition if someone tries to steal the motor then the motor current will be zero. Current transformer (not indicated in the diagram) is used in the motor starter to sense the current flowing and give following protection: Single phase protection, Dry run prevention. As the current goes to zero even when the controller has not provided any stop command or the user has not pressed the stop button, an alarm is given to the user through SMS and IVRS using GSM.

2. Main Supply Absent: In this case the main contactor (2) is open and the antitheft relay (13) is in closed condition, antitheft circuit is connected to the motor (12) and capacitor switching contactor (15) is open and C2, C3 and C4 are disconnected from the system. As the main supply (1) is not present, a separate rechargeable battery (4) is connected to the system and it supplies the entire current required for its operation.

[0065] Power supply (3) block provide the DC voltage to the controller when the Mains RYB supply (1) is present. Battery (4) is also present in the circuit and delivers the power to the controller (5) and other blocks when the mains supply (1) is not present. Push pull amplifier (11) is required to increase the current required by the system so that a sufficient voltage is measured at R1. R1 is used to measure the final output voltage. C1 is used to introduce phase shift and to drop the voltage when suddenly the main voltage (1) is present at the antitheft inputs. R2 and R3 are used to create a ladder network so that the circuit is completed to make the current flow. C2, C3, C4 are the power factor improvement capacitor.

[0066] The conventional antitheft devices/systems are applicable only to a specific rating of motor and power factor improvement capacitor. As the range is small and it’s specifically tuned to that value, the values of R and C have to be altered to meet the requirements. Therefore, there is a need to design an antitheft circuitry that remains same for any rating of the motor and the power factor improvement capacitor.

[0067] In the subject application, a novel antitheft circuit which detects whether the motor is stolen or someone had tried to short the motor and then tried to remove the motor by injecting sine wave signal of high frequency. Moreover, if the motor is stolen, the registered user receives an SMS or IVRS using GSM.

[0068] Some of the important uses and applications of the present invention, considered to be noteworthy are mentioned below:

1. The antitheft circuit is common for all ranges of motor and power factor improvement capacitor;
2. The detection range of the antitheft circuit is magnified by the amplifier (11);
3. It continues to provide antitheft protection even though the mains supply has been switched off;
4. It provides protection in manual mode (until the user presses ON button) and auto mode (until the delay time is elapsed); and
5. This antitheft circuit doesn’t depend on the contactor auxiliary block, thus, even if someone tries to manipulate and bypass the aux block, the circuit is not compromised.

[0069] Although a simple, economic and cost effective circuit for detecting motor disconnection has 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 circuitry.