Claims:1. An improved trip circuit module for earth leakage (EL) device, comprising:
at least one electronic trip unit (ETU), wherein said ETU and said EL device are communicably connected to each other;
a tripping device, wherein one or more terminals of said tripping device is communicably connected to said electronic trip unit (ETU);
wherein, when said EL device detects said earth leakage condition, said EL device adapted to switch at least one transistor unit to enable connection of said tripping device with said earth leakage device for breaking contacts apart.

2. The improved trip circuit module as claimed in claim 1, wherein said tripping device is a flux shift device (FSD).

3. The improved trip circuit module as claimed in claim 1, wherein said transistor unit is selected from a group of a metal–oxide–semiconductor field-effect transistors (MOSFET).

4. The improved trip circuit module as claimed in claim 1, wherein said EL device is powered using an isolated power supply and the voltage used to power the EL device is with respect to a floating ground.

5. The improved trip circuit module as claimed in claim 1, wherein said ETU is powered using a current transformer and the power generated to power said ETU is respect to a floating ground.

6. The improved trip circuit module as claimed in claims 1-5, wherein, when earth leakage condition is detected by said ETU, said ETU transmits at least one trip instruction to actuate one or more transistor units and thereby tripping said circuit breaker by using said FSD.

7. The improved trip circuit module as claimed in claims 1-6, wherein said earth leakage device and said ETU, isolate operate to detect earth leakage conditions independently.

8. The improved trip circuit module as claimed in claim 7, wherein said isolation of said earth leakage device and said ETU is done at the supply side.

9. An improved trip circuit module for earth leakage (EL) device, comprising:
at least one electronic trip unit (ETU), wherein said ETU and said EL device are communicably connected to each other;
a tripping device, wherein one or more terminals of said tripping device is communicably connected to said electronic trip unit (ETU);
wherein, when said earth leakage device detects said earth leakage condition, said trip circuit module adapted to disconnect said ETU with said tripping device, thereby switching a load switch and/or one or more protection relays, to enable connection of said tripping device with said earth leakage device for breaking contacts apart.

10. The improved trip circuit module as claimed in claim 9, wherein said load switch comprises a combination of at least two transistor units and at least one resistor unit.

11. The improved trip circuit module as claimed in claim 9, wherein said tripping device is a flux shift device (FSD).

12. The improved trip circuit module as claimed in claim 9, wherein said protection relay is a Normally-Closed (NC) relay.

13. The improved trip circuit module as claimed in claim 9, wherein said transistor units is selected from a group of a metal–oxide–semiconductor field-effect transistors (MOSFET).

14. The improved trip circuit module as claimed in claims 9-13, wherein, when earth leakage condition is detected by said ETU, said ETU transmits at least one trip instruction to actuate one or more transistor units and thereby tripping said circuit breaker by using said FSD.

15. The improved trip circuit module as claimed in claim 9-14, wherein said EL device is powered using an isolated power supply and the voltage used to power the EL device is with respect to a floating ground.

16. The improved trip circuit module as claimed in claim 9-14, wherein said ETU is powered using a current transformer and the power generated to power said ETU is respect to a floating ground.

17. A method for operating an electrical switching device during earth leakage conditions, using the trip circuit module as claimed in claim 1, the method comprising:
detecting, in case by means of a controller unit in an earth leakage (EL) device, said earth leakage condition in said electrical circuit;
actuating, by means of said controller unit, at least one transistor unit provided in a trip circuit module for said earth leakage device;
connecting, said EL device with at least one tripping plate and thereby transmitting at least one trip instruction to said tripping plate for breaking contacts apart.

18. A method for operating an electrical switching device during earth leakage conditions, using the trip circuit module as claimed in claim 9, the method comprising:
detecting, in case by means of a controller unit in an earth leakage device, said earth leakage condition in said electrical circuit;
actuating, by means of said controller unit, an arrangement of at least two protection relays and/or one or more transistor units, provided in a trip circuit module for said earth leakage device;
terminating, by said actuated protection relays and/or said transistor units, power supply from an electronic trip unit to a tripping plate;
switching, by said controller unit, a load switch for enabling connection of said tripping plate with said earth leakage device;
transmitting, by said controller unit, at least one trip instruction to said tripping plate for breaking contacts apart.

19. The method as claimed in claims 17 and 18, wherein during an earth leakage condition, detected by electronic trip unit, further comprises:
switching, by said electronic trip unit, at least one transistor unit and transmitting a trip instruction to said trip plate; thereby
enabling said circuit breaker contacts apart.
, Description:This application relates to an improvement in or relating to main patent application No. 201621002556 filed on January 22, 2016 and is an application for patent of addition thereto and accordingly the entire disclosure of such main patent application is hereby incorporated by reference.

TECHNICAL FIELD OF THE INVENTION
The present invention relates to an improved mechanism for protecting an electric circuit during a fault condition, and more particularly relates to a mechanism for isolating earth leakage detection devices and the electronic trip unit so that both the earth leakage detection devices and the electronic trip unit can independently trip a switching device such as a circuit breaker, during an earth leakage fault in a low voltage applications.

BACKGROUND AND THE PRIOR ART
The Earth leakage (EL) device is a safety device used in electrical installations with high earth impedance to prevent shock and to protect the people and appliances arranged in an electrical circuit from residual currents. Many times, earth leakage devices are used in conjunction with an electrical switching device, such as a circuit breaker, molded case circuit breaker (MCCB) and the like, and for sensing earth leakage faults and actuating a tripping mechanism in the circuit breaker that opens the contacts upon the detection of a leakage fault.
The circuit breakers has its own Electronic trip unit (ETU) to sense the residual current and accordingly trip the device either in overload or short circuit using a Flux shift device (FSD). The electronic trip unit is the part of a circuit breaker that opens the circuit in the event of a thermal overload, short circuit or earth leakage by use of tripping/actuating mechanism.

Earth leakage devices do not have a breaking mechanism as with the circuit breaker. It is connected to the ETU of the circuit breaker through some communication medium or connected to another tripping device which is also connected to the trip plate like the FSD. So, in order to break power supply to the load during a fault condition, leakage device adapted to send a trip signal to the trip plate which acts upon the breaking/tripping mechanism thereby separating the contacts of the circuit breaker.

Normally, during the fault condition, the contacts are separated by using another FSD connected to the trip plate or in case of high end ETU are provided where communication medium is present such that the earth leakage devices are connected through some communication medium to send the tripping signal to the ETU and thereby the ETU sends a trip instruction to the tripping device. But in such situations, for the earth leakage devices to be operable there is a need of high end ETU and the communication media, and without them there won’t be any signal send to the tripping mechanism.

Thus, in order to overcome the requirement for a multiple FSD and the high end ETU, there is a need for a trip circuit module for use with the earth leakage device, such that one FSD can be used to provide tripping instruction the circuit breaker.

Reference is made to US6784770B2, provides an actuating mechanism in which earth leakage module and the circuit breaker are connected mechanically.

Reference is made to US4786885A, uses a shunt trip to actuate the circuit breaker for using the different electrical accessories.

The prior art document US ‘770B2, has an inbuilt tripping mechanism which has a plunger connected to the auxiliary switch carrier acting on the trip plate of the tripping mechanism of the circuit breaker. Mechanical linkage to the trip plate has to be provided in the circuit breaker as it operates when the plunger is actuated when an earth leakage occurs. In the prior art document US ‘885A, for tripping the different electrical accessories which connected the circuit breaker, an additional Shunt trip is required with the existing FSD for tripping the circuit breaker. Moreover, it takes the space of the shunt which can be used by other devices to trip the circuit breaker.

However, the following are the problems of the prior art which is addressed by the present invention:
• Using a separate shunt trip device as disclosed in US ‘885A, to operate a tripping mechanism to trip the circuit breaker, requires additional space for actuating or separating electrical contacts to trip the circuit breaker.
• If additional actuating mechanism is used to trip the circuit breaker, then it requires separate actuating/tripping mechanism to be built inside the circuit breaker to accept the plunger action of EL module and actuate the trip plate to trip the circuit breaker.

Further, the main patent application 201621002556 is applicable only for high voltage applications like 440V L-N. Since, the power supply designing is dependent upon the line voltage and the load connected at the output, therefore if the line voltage is more and the load current requirement is more, then the size of the transformer used at the primary side will be very huge and there is requirement of extra space to accommodate that size.

Thus, to address the hitherto problems of the prior art, a trip circuit module is provided for use with the earth leakage module, that eliminates the need for a separate tripping or actuating mechanism to be built inside the electrical switching devices. Besides, the present invention is also directed to provide an improvement over the main application such that the isolation of the earth leakage module and the electronic tripping unit can be done in case when the load requirement is less and the input line voltage is less.

OBJECTS OF THE INVENTION
A basic object of the present invention is to provide an improved trip circuit module that enables isolation of the earth leakage device and the electronic tripping unit at, when the input voltage is low and the load requirement is low.

Another object of the present invention is to provide an improved trip circuit module in a circuit breaker that enables breaking of circuit breaker contacts using a single tripping device when earth leakage condition is detected in an electrical circuit.

Yet another object of the present invention is to provide an improved trip circuit module such that both the electronic trip unit (ETU) and the EL device can be independently or simultaneously operated for detecting fault due to leakage current and thereby tripping a circuit breaker without the need for the additional tripping mechanism.
These and other advantages of the present invention will become readily apparent from the following detailed description read in conjunction with the accompanying drawings.

SUMMARY OF THE INVENTION
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.

According to one aspect of the present invention there is provided an improved trip circuit module for earth leakage (EL) device, comprising:
at least one electronic trip unit (ETU), wherein said ETU and said EL device are communicably connected to each other;
a tripping device, wherein one or more terminals of said tripping device is communicably connected to said electronic trip unit (ETU);
wherein, when said EL device detects said earth leakage condition, said EL device adapted to switch at least one transistor unit to enable connection of said tripping device with said earth leakage device for breaking contacts apart.

In one aspect, there is provided a method for operating an electrical switching device during earth leakage conditions, using the trip circuit module, the method comprising:
• detecting, in case by means of a controller unit in an earth leakage (EL) device, said earth leakage condition in said electrical circuit;
• actuating, by means of said controller unit, at least one transistor unit provided in a trip circuit module for said earth leakage device;
• connecting, said EL device with at least one tripping plate and thereby transmitting at least one trip instruction to said tripping plate for breaking contacts apart.

According to second aspect, the present invention provides an improved trip circuit module for earth leakage (EL) device, comprising:
at least one electronic trip unit (ETU), wherein said ETU and said EL device are communicably connected to each other;
a tripping device, wherein one or more terminals of said tripping device is communicably connected to said electronic trip unit (ETU);
wherein, when said earth leakage device detects said earth leakage condition, said trip circuit module adapted to disconnect said ETU with said tripping device, thereby switching a load switch and/or one or more protection relays, to enable connection of said tripping device with said earth leakage device for breaking contacts apart.

In second aspect, there is provided a method for operating an electrical switching device during earth leakage conditions, using the trip circuit module, the method comprising:
• detecting, in case by means of a controller unit in an earth leakage device, said earth leakage condition in said electrical circuit;
• actuating, by means of said controller unit, an arrangement of at least two protection relays and/or one or more transistor units, provided in a trip circuit module for said earth leakage device;
• terminating, by said actuated protection relays and/or said transistor units, power supply from an electronic trip unit to a tripping plate;
• switching, by said controller unit, a load switch for enabling connection of said tripping plate with said earth leakage device;
• transmitting, by said controller unit, at least one trip instruction to said tripping plate for breaking contacts apart.

Briefly, the present invention shows an improvement or modification over the originally filed patent application no. 201621002556, by providing an improved trip circuit module which enables isolation of earth leakage device and the electronic trip unit at the supply side itself, whereby the EL device is powered using an isolated power supply while the ETU is powered using current transformer and the voltage used to power the EL module and the ETU is with respect to the floating ground. This enables the trip circuit module in earth leakage device to be utilized in a low voltage scenarios whereby the load requirement is less and the input voltage is less.
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 following drawings are illustrative of particular examples for enabling methods of the present invention, are descriptive of some of the methods, and are not intended to limit the scope of the invention. The drawings are not to scale (unless so stated) and are intended for use in conjunction with the explanations in the following detailed description.
Figure 1 illustrates the block diagram of the Earth leakage module in conjunction with circuit breaker, according to one embodiment of the present invention.
Figure 2 shows the improved trip circuit module for earth leakage module in circuit module, according to another embodiment of the present invention.
Figure 3 shows the improved trip circuit module for earth leakage module in circuit module when the earth leakage fault is detected by the EL device, according to one embodiment of the present invention.
Figure 4 shows the improved trip circuit module for earth leakage module in circuit module when a fault is detected by the ETU, according to one embodiment of the present invention. Such faults can be due to earth leakage, overloads, short circuits etc. or the like.
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 INVENTION
The following description with reference to the accompanying drawings is provided to assist in a comprehensive understanding of exemplary embodiments of the invention as defined by the claims and their equivalents. It includes various specific details to assist in that understanding but these are to be regarded as merely exemplary. 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 and spirit of the invention. In addition, descriptions of well-known functions and constructions are omitted for clarity and conciseness.
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.
It is to be understood that the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise.
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.
It is also to be understood that the term “module” is used in the specification to indicate an apparatus, unit, component and the like. The term “means” when used in the specification is taken to specify the mode by which desired result is achieved.

The present invention can be implemented with an electrical switching system that may include but not limited to, circuit breakers or thermo-magnetic breaker, molded case circuit breaker (MCCB) , earth leakage circuit breaker (ELCB) and the like.

The present invention relates to a trip circuit module that can be provided with an earth leakage module wherein both the devices, i.e., the trip circuit module and the earth leakage (EL) device can work independently by connecting to one or more terminal of the flux shift device (FSD) and when worked in conjunction, the ETU in the circuit breaker can be always be connected to the FSD.

In one embodiment, the trip circuit module comprises one or more transistor units which are selected from a group of a metal–oxide–semiconductor field-effect transistors (MOSFET).

Reference is made to figure 1 which illustrates a block diagram of the Earth leakage module in conjunction with circuit breaker. The earth leakage device and said ETU, simultaneously or independently operate to detect earth leakage conditions in an electric circuit. In one implementation, the tripping device used can be a flux shift device (FSD).

Reference is made to figure 2(a) which shows the improved trip circuit module for earth leakage module in circuit module, according to another embodiment of the present invention. Figure 2(b) gives details of the improved trip circuit module for earth leakage module in circuit module, according to the embodiment of the present invention.

Reference is also made to figure 3 which shows the trip circuit module for earth leakage module in circuit module when the earth leakage fault is detected by the EL device according to one embodiment.

Reference is made to figure 4 which shows the improved trip circuit module for earth leakage module in circuit module when the fault is detected by the ETU, according to one embodiment of the present invention.

Unlike the main application, where the power supply that may be used to power an EL module is non-isolated and thereby the ground is connected to the neutral, however, in the present invention, the EL module may be powered by means of an isolated power supply. So the voltage used to power the EL module is with respect to floating ground as shown in figure 2. For powering the ETU, Current transformers may be used. Again these are isolated from the mains power supply. So the power generated to power the ETU is also with respect to floating ground. In the present invention, the basic operation of using a common FSD may be done at the supply side itself. This type of method can be implemented where there is no space constraint. As relay will consume space and voltage at the primary should be low i.e. 230V L-N, therefore isolation transformer is used at the primary side and also it depends on the wattage of the power supply which may be consumed at the load side.

In one embodiment, as shown in the figure 1, the FSD has two terminals illustrated as A1 and A2, which are connected to EL module and from EL module B1 and B2 terminals are connected to the ETU. When said ETU and EL devices are independently used for detecting earth leakage conditions in an electric circuit, for example if only ETU is used, then A1 and A2 terminals of FSD are directly connected to the ETU and if Earth leakage device is connected only with the electrical switching device such as thermo-magnetic breaker, then A1 and A2 are connected to the EL module without any connection from B1 and B2.

In the present invention, as shown in figure 2, the ETU can be powered using a current transformer (CT), wherein the ground can be floating and the earth leakage devices/modules can be powered directly from line supply. So unlike the main application, in the present invention, isolated power supply can be used due to which both the supply voltage powering the EL device and the ETU are isolated and have separate ground potential. So when leakage current is sensed by the earth leakage (EL) devices it drives one or more MOSFETs which enables disconnection of the ETU’s connection with the FSD, thereby connecting the FSD with the earth leakage device, and tripping the circuit breaker by breaking the circuit breaker contacts apart.

In one embodiment, the diagram shown in figure 3 and 4, is when earth leakage device is connected with the ETU.

Case 1: ETU senses the Fault:
The FSD may be always connected to the ETU even if the Earth leakage device is not powered. Thus when ETU senses the fault and gives a trip instruction to turn ON a MOSFET M4 which is inside the ETU, thereby tripping the circuit breaker by breaking the contact apart. Thus, ETU will take control over the FSD, then the following MOSFET (M4) will be turned ON and the current flow would be as shown in figure 4.

Case 2: EL module senses the fault:
A trip command is given to the MOSFET M5 by EL module such that the FSD pops out thereby tripping the circuit breaker. Thus, the EL will take control over the FSD then following MOSFET (M5) will be turned ON and the current flow would be as shown in figure 3.

In another embodiment, the trip circuit module can additionally comprise an arrangement of at least two protection relays and at least four MOSFETs (M1, M2 M3, M4, M5) as shown in figure 2. In the present invention, the protection relays as shown in figure 2, can be used as to provide additional protection to the trip circuit module. Alternatively, if relays are not used, then MOSFET devices with high voltage rating may also be used.

In another embodiment, when, EL device is used to measure the ground fault/earth leakage condition, then the protection relays and the MOSFETS are turned ON to disconnect said ETU with said FSD, switching a load switch to enable connection of said FSD with said earth leakage device for breaking said contacts apart. The load switch comprises a combination of at least two transistor units (M1, M2 and R) and at least one resistor unit as shown in figure 2.

In another embodiment, as shown in figure 2, when EL module senses the fault, the controller unit actuates the MOSFET M3 high by sending an instruction to the port pin 1.2 of the controller unit which in turn switch ON the protection relay, thereby disconnecting the supply from ETU to the FSD. The protection relay at port 1.2 is communicably connected to the MOSFET M3.

However, when earth leakage condition is detected by the electronic trip unit, the ETU may be enabled to transmit a tripping instruction to turn ON MOSFET M4 and thereby tripping said circuit breaker by using the FSD. The ETU in the circuit breaker can always be connected to the FSD.

In another embodiment, the diagram shown in figure 2 is when earth leakage device is connected with the ETU.
Case 1: ETU senses the Fault
The protection relays used in the trip circuit module may be a normally closed (NC) contact relay so the FSD may be always connected to the ETU even if the Earth leakage device is not powered. Thus when ETU senses the fault and gives a trip instruction then MOSFET M4 can be turned ON which is inside the ETU there by tripping the circuit breaker by breaking the contact apart.

Case 2: EL module senses the fault
When EL module senses the fault, the controller unit actuates the MOSFET M3 high by sending an instruction to the port pin 1.2 of the controller unit which in turn switch ON the protection relay, thereby disconnecting the supply from ETU to the FSD. As shown in figure 2, the relay at port 1.2 is communicably connected to the MOSFET M3.

After that operation, the controller transmit a turn ON instruction to the port pin 1.3 for switching ON the MOSFET M1 and thereby turning ON the MOSFET M2. Now, the supply of EL module (VCC) is connected to the FSD. The ETU may be powered from current transformer (CT) (not shown in diagram) so it has a floating ground and the power supply used in EL module is an isolated SMPS. So, when M2 turns ON, the MOSFET M4 ground is separate and won’t let it turn ON even if fired by ETU. Thus helps to avoid the damaging of MOSFET M4. Now when a trip instruction is given to the port pin 1.1 of the controller unit, the MOSFET M5 is switched ON, and thereby FSD pops out thereby tripping the circuit breaker.

In the embodiment, the protection relays are additionally provided in the trip circuit module wherein the trip circuit module is used with the earth leakage device. Therefore no separate tripping device or separate actuating mechanism is required to be built inside the electronic trip unit. No extra space is required inside the breaker as it is built inside the EL module. It’s simple to use and doesn’t require to build an actuating mechanism.

Some of the noteworthy features of the present invention, considered to be noteworthy are mentioned below:
1. The present invention provides an electric trip module by which the ETU and the EL device can be independently or simultaneously used for detecting the earth leakage fault by connecting to a common tripping device such as a FSD. Thus, the EL device can itself enable protection of an electric circuit during a fault condition without the need to ETU. The isolation of the EL device and the ETU is done at the supply side itself.

2. The present invention may be used for low voltage applications whereby the load requirement is less and the input voltage is less. So transformer at the primary can be used as its size would be smaller.

3. The present invention doesn’t require an additional tripping device as two relays are used inside the trip circuit module which helps in to use the same tripping device. The trip circuit module is used with the EL device. Therefore, separate FSD may not be required for earth leakage devices.

4. No extra space is required inside the breaker to provide the tipping device inside the breaker device and no mechanism linkages is required.

5. In the present invention, isolated power supply is used due to which both the supply voltages to the EL and ETU devices are isolated and have separate ground potential. The voltage used to power the EL and the ETU device is with respect to the floating ground. Thus, the ETU can trip the electrical switching device even if the EL device is not powered.

6. The solution of the present invention is fail proof solution as both the grounds are isolated. Since, the present invention uses an isolated switched-mode power supply (SMPS) for powering the EL device and ETU is powered using a CT in which primary and secondary are isolated using an iron core. As both are isolated power the ground would be floating too. So, ETU and EL device be isolated from each other as their ground potential is different.

7. The mechanism for operating an electrical switching device during an earth leakage conditions in an electrical circuit is a low cost solution. In one implementation, the present invention can be implemented using only MOSFET units which are commonly available at a very cheap cost as compared to using an extra shunt trip or a separate actuating mechanism.

Although an improved trip circuit module for earth leakage device 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 improved trip circuit module for earth leakage device and a method.