Claims:We claim:

1. An U-shaped earth leakage module configured to fit a circuit breaker while installation, the U- shaped earth leakage module comprising:
a bottom housing having,
• a core balance current transformer (CBCT) for detecting leakage current flowing in a circuit, the core balance current transformer (CBCT) having closed loop core material wound with high permeable nanocrystalline material to sense lowest of the leakage current flowing through the circuit breaker,
• a power card with voltage contacts card acting as a power source,
• a plurality of internal phase barriers to provide additional clearance and creepage to the circuit breaker;
a right cover coupled to right side of the bottom housing, the right cover having,
• a mechanically actuated trip indicator assembly for displaying actual status of the module, and
• electronics access flap;
a left cover coupled to the left side of the bottom housing, the left cover encapsulating an electronic control circuit (ECC), the electronic control circuit (ECC) configured to process leakage of detected by the CBCT;
a settings rear flap to cover the rear side of the circuit breaker; and
an isolation module having the long isolating contacts, IM Springs, IM lock-1, IM Bridge and IM Slider, the isolation module configured to disconnect power supply when required.

2. The U-shaped earth leakage module of claim 1, further comprising front cover, indicator sticker, shunted FSD wire harness, CBCT wire harness and termination cables.

3. The U-shaped earth leakage module of claim 1, wherein thecore balance current transformer (CBCT) having closed loop core material is wound with low permeable materials selected from mumetal, CRGO and CRNGO if the sensing current is high or the space available for the CBCT is high.

4. The U-shaped earth leakage module of claim 1, wherein the electronic control circuit comprises a preprogrammed controller which compares the incoming signal with respect to the programmed waveforms, various limits for the alarm and tripping command outputs of the module.

5. The U-shaped earth leakage module of claim 1, wherein the U-shaped earth leakage module is capable of being used for all types of termination.

, Description:Field of the invention

The present invention relates to U- shaped earth leakage module for circuit breakers, and more particularly, to the circuit breakers wherein the earth leakage protection is not an option from the circuit breaker within and intended to operate under circumstances where the said protection is required.

Background of the invention

Earth leakage modules of existing circuit breakers incorporate trends as mentioned in the figures 1 and 2. Specifically, figure 1 shows an earth leakage module for circuit breaker in L-shape and figure 2 shows the earth leakage configuration as bottom mount.

Specifically, L-shaped configurations of the earth leakage module as shown in figure 1 are generally used in the circuit breaker that is mounted on a distribution board. The settings are available for the customer at the 45 mm cutout available as a user interface area.

Further, the bottom mount configuration of the earth leakage module is generally used in the circuit breaker that is mounted in a switch board panel which are generally operated through ROMs (Rotary Operated Mechanisms), EOMs (Electrically Operated Mechanisms) or by means of automation systems.

Various patent and patent applications are available in the prior art depicting configuration of the earth leakage module for the circuit breaker.

Specifically, a Chinese Patent CN 102243957 discloses a moulded case circuit breaker with residual current protection. The device includes a base, contact interrupter module group, operating mechanism, residual current release, lid assembly, partitions, thermal magnetic release group, insulation, zero-sequence current transformer, leakage control unit, said contact interrupter module group fixed to the base, the operating mechanism fixed to the base and contact interrupter module group, the remaining current release mounted on the contact interrupter module group, and the drain is connected via a wire control assembly, the thermal-magnetic release set by each phase zero-sequence current transformer located in contact interrupter module group and base Take electric wire holder, the leakage control assembly disposed between the thermal-magnetic release set and zero-sequence current transformer, the leakage control components are connected to three-phase thermal magnetic release group, the said cover assembly is mounted on the base.

Another European Patent No. EP 1261005 A1, discloses a mechanism for an enclosed residual current-operated circuit breaker, has a relay provided with a piston adapted to act on a tripping mechanism, a handle for resetting the tripping mechanism and for acting on the piston of the relay in order to return it to the normal operating condition, a pre adjusted elastic member arranged between the handle and the piston so that the force applied to the piston is set by means of the elastic member and does not depend on the force applied to the handle.

However, the prior art earth leakage modules have following disadvantages.

1. The L-shaped configurations of the earth leakage module limit the user from using various types of terminals and allow only flexible cable termination to the circuit breaker.

1. In the L-shaped configurations of the earth leakage module, the cable termination also is complex for insertion and requires opening of the module for installation. Figure 16 which show how the cable (32) is getting squeezed inside CBCT assembly (23) and difficulty in cable insertion for the user to properly find out the breaker terminal while inserting through the module. Thus, the L-shaped module needs to be opened before installation in order to properly locate the cable without damaging the module. Further, rigid cables cannot be used as flexible cables are required here.

2. In the L-shaped configurations of the earth leakage module, a trained technician help is required for the installation.

3. In the L-shaped configurations of the earth leakage module, the rating of the module is limited to 500V max because of the space congestion and poor utilization.

4. The bottom mount configuration of the earth leakage module is used for those circuit breakers which don’t fit in the distribution boards. Hence primary requirement of settings available to user interface is lost.

5. The bottom mount configuration of the earth leakage module adds another termination in line to the circuit breakers termination adding up the additional mV(milli Volt) drop to the circuit thereby increasing the overall temperature rise of the circuit breaker.

6. Use of magnetic flapper or relay based indications leads to defective indication of the trip status of the earth leakage module.

Accordingly, there is exists a need to provide an earth leakage module for circuit breaker, which overcomes abovementioned drawbacks.

Objects of the invention

An object of the present invention is to provide protection of loads when required with earth leakage protection.

Another object of the present invention is to provide anearth leakage module for circuit breaker with maximum space utilization in the module.

Summary of the invention

Accordingly, the present invention provides a U-shaped earth leakage module configured to fit a circuit breaker while installation. The U- shaped earth leakage module comprises a bottom housing having a core balance current transformer (CBCT) for detecting leakage current flowing in a circuit. The core balance current transformer (CBCT) includes closed loop core material wound with high permeable nanocrystalline material to sense lowest of the leakage current flowing through the circuit breaker. The bottom housing further comprises a power card with voltage contacts card acting as a power source, and a plurality of internal phase barriers to provide additional clearance and creepage to the circuit breaker.

Further, the U-shaped earth leakage module comprises a right cover coupled to the right side of the bottom housing. The right cover includes a mechanically actuated trip indicator assembly for displaying actual status of the module, and electronics access flap.

Furthermore, the U-shaped earth leakage module comprises a left cover coupled to the left side of the bottom housing. The left cover encapsulates an electronic control circuit (ECC) wherein theelectronic control circuit (ECC) is configured to process leakage detected by the CBCT.

The U-shaped earth leakage module also includes a settings rear flap to cover the rear side of the circuit breaker, and an isolation module configured to disconnect power supply.

Brief description of the drawings

Figure 1- 2and 16 shows a schematic drawing of an earth leakage module for circuit breaker, in accordance with the prior art;

Figure 3 shows a schematic drawing of an earth leakage module for circuit breaker, in accordance with the present invention;

Figure 4 shows a front view earth leakage module for circuit breaker, in accordance with the present invention;

Figure 5 shows an exploded view of the earth leakage module for circuit breaker, in accordance with the present invention;

Figure 6 - 15 and 17 shows various components of the earth leakage module of the present invention.

Detailed description of the invention

The foregoing objects of the present invention are accomplished and the problems and shortcomings associated with the prior art, techniques and approaches are overcome by the present invention as described below in the preferred embodiment.

Accordingly, the present invention provides a U -shaped earth leakage module for circuit breaker. The U -shaped earth leakage module provides protection of loads when required with the earth leakage protection. Further, the U-shaped earth leakage module providemodule for circuit breaker with maximum space utilization in the module.

The present invention is illustrated with reference to the accompanying drawings, throughout which reference numbers indicate corresponding parts in the various figures.

Referring now to figure 4- 15 and 17, there is shown a U-shaped earth leakage module (hereinafter “the module (100)”) for circuit breaker (not shown) in accordance with the present invention.

The module (100)”) comprises a bottom housing (10), a right cover (20), a left cover (30), a settings rear flap (42) and an isolation module (44).

The bottom housing (10) comprises a core balance current transformer (CBCT) (12).The CBCT (12) detects leakage current flowing in the circuit. The CBCT (12) comprises of a closed loop core material wound using high permeable nanocrystalline material in order to sense the lowest of the leakage current flowing through the circuit breaker. The CBCT (12) of the present invention has capability to sense the leakage currents as low as 1mA. However, it may be evident to those skilled in the art that other low permeable materials like mumetal, CRGO and CRNGO can also be used if the sensing current is high or the space available for the CBCT is high.
The CBCT (12) forms the heart of the module (100). The CBCT (12) is located in the bottom housing (10) as shown in the figure 7.

The bottom housing (10) further includes a power card (14) with voltage contacts card acting as a power source. The power card (14) is the voltage tapping unit of the module (100). The voltage contacts (16) as shown in figure 4 are the part of the power card (14). Figure 10 shows the assembly of power card (14) and internal phase barriers (18) into the U-shaped bottom housing (10).

The internal phase barriers (18) are intended to provide additional clearance and creepage to the circuit breaker. The internal phase barriers (18) also add to the customer flexibility in the termination.

Further, the right cover (20) coupled to the right side of the bottom housing (10). The right cover (20) includes a mechanically actuated trip indicator assembly (22) for displaying actual status of the module (100), and a electronics access flap (24). The assembly of right cover (20) along with the trip indicator assembly (22) and the electronics access flap (24) is shown in the figure 9. The right cover (20) also includes various access points that are required to interact with various other accessories of the breaker such as
shunt release and FSD wire harness port (26), shunt release mechanical actuation port (27), and electronic release port (28).

The trip indicator assembly (22) includes two components wherein the sliding components gets actuated by either the shunt release or the shunted FSD (29) and thus giving trip indication to the customer through indicator sticker (25). Specifically, exploded view (front and back) of thetrip indicator assembly (22) isshown in figures 8a and 8b. Figure 13 shows the integration of shunted FSD (29) assembled always inside the circuit breaker with trip indicator assembly (22) enabling the visual indication of the trip event by earth leakage module. Also use of mechanical indication gives the true indication all the time irrespective of the external field issues.

Further, the left cover (30) of the module (100) includes an electronic control circuit (ECC) (32). The processing of detected leakage by the CBCT (12) is done by the ECC (32) configured in the left cover (30). The ECC (32) holds the control circuitry of the module (100) which is controlled by a preprogrammed controller which comparesincoming signal with respect to programmed waveforms and various limits for the alarm and tripping command outputs of the module. The ECC (32) is encapsulated inside the left cover (30) exposing only the setting knobs (34) and (36) and a test button (38). The encapsulation of the ECC (32) inside left cover (30) and the settings rear flap (38) is shown in the figure 6. The settings rear flap (38) is used to cover the rear side of the circuit breaker in the module (100).

The two setting knobs (34) and (36) govern the leakage current values and tripping time values of the module (100). The test button (40) is used for the verification of the module’s (100) positive working status and periodic checks.

The module (100) power up is managed by three different modes,
1. Power tapping from the circuit breaker lines
2. Auxiliary power supply
3. Self-power up using separate CT modules attached to the module

The isolation module (44) is used to disconnect the module (100) power when in testing or maintenance mode. The voltage contacts (VC) (16) are the contacts used to tap power from the circuit breaker lines.The isolation module (44) is kept intentionally inaccessible to the customer or the operator as the module (100) needs to be operated while the installation is open for maintenance or under testing condition. Specifically, the long isolating contacts (46), IM springs (48), IM lock-1 (50), IM bridge (52), and IM slider (54) are combined to form the isolation Module (IM) (44) of the circuit breaker. The isolation Module (IM) (44) breaks the power supply of the module (100) during maintenance and high voltage and impulse testing of the circuit breaker.

Apart from the components mentioned above, the module (100) also comprises components therein such as afront cover (56), indicator sticker (58), shunted FSD wire harness (60), CBCT wire harness (62), and termination cables (64).

The voltage is tapped from the lines of the circuit breaker and the same is used for the powering up the module (100) as well as various other indications and communications. The power circuit includes the components associated with the operating voltage of the module (415V/690V/1000V) according to the circuit breaker specifications and load specifications.

The status of the module during testing, installation and working can be seen from the indicator (68).

Various indications and communications that are required to be given to the customer side can be taken from the wired contact terminals (70).

Figure 11 shows completed assembly of the earth leakage module (100) with standard spreader terminated breakers. As you can see, the settings panel of the earth leakage module (100) is in line with the circuit breaker projected face that is available to the customer for access.

Figure 12 shows add-on spreader terminals that are given along with the earth leakage module (100) to assist spreader terminated breakers.

For other kind of terminations, the cables, links and tunnel cables, cable lugs remain same and ready to refit as available with the circuit breaker.

The following features are available to the customer when the earth leakage module (100) is mounted with the circuit breaker and is inside the distribution board,
1. Current and time setting knobs
2. Test push button
3. Alarm indication LED which will be available with various blinking levels for 25% and 75% of I?n (rated leakage current) respectively
3. Trip indication of the earth leakage module

The earth leakage module (100) is used to find out the leakage current flowing through the circuit and thereby protecting the load side from the defects due to the earth leakage currents. The earth leakage can be caused by various means and the majority of the events are as listed below,
1. Personnel contact on the live wires
2. Machine’s wire touching the grounded body by mistake or by insulation failures
3. Intentional leakage current creating operations involved in arc furnaces and welding setups.

The earth leakage module (100) uses three critical components for capturing, analysis and tripping of the breaker when the leakage current is present
The three critical components are as follows,
1. The CBCT (12) for sensing the leakage current
2. The ECC (32) for analysis of the leakage current value and type
3. The Shunted FSD (29) or Shunt release for tripping the breaker in case of trip command from ECC (32).

The CBCT (12) is placed in such a manner that all the lines of the circuit breaker passes through it. The CBCT (12) senses the magnetic fluxes of various currents flowing in the circuit breaker and the resultant flux that is flowing within is the average sum of all the currents in the circuit breaker.

When in normal operating condition, the CBCT’s (12) core has a resultant magnetic flux of zero and hence no waveform is available for the ECC (32) to process and act. The arrangement of conductors and CBCT (12) is shown in the figure 14.

Thus, by covering all the lines inside the circuit breaker, the earth leakage module (100) is capable of protecting 2 pole, 3 pole and 4 pole loads connected to the circuit breaker.

This output of the CBCT (12) is given to the ECC (32) and the ECC (32) process the waveform with respect to the pre-stored trigger values for both alarm and tripping.The earth leakage module (100) can give alarm to the end user based on the percentage earth leakage current (generally 25% and 75% are the values with different blinking methods for both)flowing in the circuit and can give tripping command to the shunted FSD (29) or Shunt release based on the earth leakage current tripping threshold.

The alarm is given to the customer through two of the six wired contacts available at the bottom left of the module as shown in 70 in figure 4.

The alarm is given as a warning to the customer and that gives the opportunity to check the known source of earth leakage current. The tripping command is generated once the threshold value of the ECC (32) is breached by the CBCT (12) input waveform.

Figure 15 shows the wire harness (62) connectivity inside the earth leakage module (100) of the above discussed three critical components. Thus the three critical components describe above of earth leakage module (100) coordinates the earth leakage current detection in the U-shaped earth leakage module (100).

The U-shaped earth leakage module (100) covers all the above explained components, sub-assemblies or sub-modules inside and completes the requirement of earth leakage protection in the accompanied circuit breaker.

Advantages of the invention

1. The U-shaped earth leakage module (100) occupies similar space as like the conventional L-shaped earth leakage module and still provides the following features.
a. All types of termination available in the circuit breaker can be used along with earth leakage module
b. Enclosed wire routing for accessing all the sub-modules in the breaker
c. Enables settings availability at the 45 mm distribution cut out for the customer
d. Occupies the same space as an L-shaped earth leakage module
e. Mechanical trip indicator assembly gives true indication of the earth leakage module

2. In the U-shaped earth leakage module (100), customer termination need not required to be changed.

3. The U-shaped earth leakage module (100) provides hassle free wiring.
4. The U-shaped earth leakage module (100) provides visual indication of all module events in the visible cut out region.

5. In the U-shaped earth leakage module (100) Module isolation possible during testing and maintenance.

The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the present invention and its practical application, and to thereby enable others skilled in the art to best utilize the present invention and various embodiments with various modifications as are suited to the particular use contemplated. It is understood that various omissions and substitutions of equivalents are contemplated as circumstances may suggest or render expedient, but such omissions and substitutions are intended to cover the application or implementation without departing from the spirit or scope of the claims of the present invention.