FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. TITLE OF THE INVENTION
Seesaw type interlocking arrangement for electrical devices
2. APPLICANT(S)
(a) NAME : Larsen and Toubro Ltd.
(b) NATIONALITY: Indian
(c)ADDRESS : L&T House, Ballard Estate, Mumbai-400 001, India.
3. PREAMBLE TO THE DESCRITION
PROVISIONAL COMPLETE
The following specification describes The following specification particularly describes the
invention invention and the manner in which it is to be performed
4. DESCRIPTION (Description shall start from next page)
5. CLAIMS (not applicable for provisional specification. Claims should start with the preamble -"I/We claim" on separate page)
6. DATE AND SIGNATURE (to be given on the last page of specification)
7. ABSTRACT OF THE INVENTION (to be given along with complete specification on the separate page)
Note:
*Repeat boxes in case of more than one entry
*To be signed by the applicant(s)or the authorized registered patent agent
*Name of the applicant should be given in full, family name in the beginning
*CompIete address of the applicant should be given stating with postal index no. / code, state and
country
*Strike out the column which is/are not applicable

Seesaw type interlocking arrangement for electrical devices
Field of the invention
The invention relates to a crank with "AND" logic arrangement for electrical devices and particularly to a crank with "AND" logic arrangement for mechanical interlock with clutch type cables for more than two Air circuit breakers.
Background of the invention
A circuit breaker is a mechanical switching device, capable of making, carrying and breaking currents under normal circuit conditions and also making, carrying for a specified time and breaking currents under specified abnormal circuit conditions such as those of short circuit. In electrical transmission systems, it is often required to connect number of electrical devices for providing rated current. Also multiple alternate arrangements are required for transmitting the current in the case there is failure from one source or a situation where current is obtained from two different sources. It is necessary to provide an arrangement where current from multiple sources is obtained based on the requirement by selecting the required device in the transmission series. This arrangement is possible using programmable logic controllers which select the required devices based on the selection logic. However an electromechanical arrangement is required which will combine the functions of "AND logic" and "OR logic ".
Some electrical installations require interlocking between various switches connecting different power sources to installation. Interlocking prevents undesirable paralleling of sources and further damages to installation. Interlocking scheme with two incomer ACBs & one bus coupler, mandatory condition is maximum two ACBs can be closed at any point of time. In the present devices, such arrangement is provided in traditional devices but the arrangement cannot be generalized and made applicable to range of electrical devices. A general

arrangement is required where selection of devices will be easier and where such arrangement offers modularity.
In case of three incomers, this arrangement requires maximum any one circuit breaker should ON at any point of time. This mechanical interlock (MIL) arrangement requires crank with OR logic, hence any one incoming cable out of two cables need to be pulled to operate tripping crank.
In case of two incomers & one bus coupler, this arrangement requires maximum two ACB should ON at any point of time. This mechanical interlock (MIL) arrangement requires crank with AND logic, hence in this case two incoming cables must be pulled to operate tripping crank.


Object of the invention
One object of the present invention is to provide an interlocking scheme with two incomer ACBs and one bus coupler where mandatory condition is maximum two ACBs can be closed at any point of time.
Another object of the present invention is to provide an "AND logic" arrangement by seesaw movement of crank lever where two incoming cables are attached at the ends of crank lever. When any one of the cable is pulled, crank remains stationery due to seesaw action of lever but when two cables are pulled it will cause rotational movement of the crank.
Summary of the invention
An "AND logic" arrangement is provided by seesaw movement of crank lever where two incoming cables are attached at the ends of crank lever. When any one of the cable is pulled, crank remains stationery due seesaw action of lever. But when two cables are pulled it will cause rotational movement of the crank which activates the tripping mechanism of circuit breaker.
Description of drawings
Fig. 1 shows a schematic view of crank with AND logic arrangement.
Fig. 2 shows a case 1 where cable A pulled in upward direction
Fig. 3 shows Case 2 where cable B pulled in upward direction
Fig. 4 shows Case 3 where cable A and Cable B are pulled in upward direction

Components:
1. Air circuit breaker right side plate
2. Trip shaft
3. Crank (with AND logic)
4. Cable mounting plate
5. Cable guide
A. Cable A
B. Cable B
Detail description of the invention
Some electrical installations require interlocking between various switches connecting different power sources to installation. Interlocking prevents undesirable paralleling of sources and further damages to installation.
Interlocking scheme with two incomer ACBs and one bus coupler, mandatory condition is maximum two ACBs can be closed at any point of time. To meet this condition ANDing of cable movements of two ACBs is done at trip shaft reminder third ACB.
This invention consists of crank with AND logic (3], trip shaft (2), mounting plates (4), incoming cables (5) and ACB right plate (l).Crank [3] is mounted on trip shaft (2] of circuit breaker. Any upward rotation of the trip shaft (2] causes tripping of the ACB or prevents closing of the circuit breaker. Crank (3] has lever which is free to rotate to in 360 degrees. Crank [3] lever has holes for incoming cable (5] fixing at ends of the lever. Pull force (FP) acting on crank (3) lever due to incoming cable (5) cause seesaw action of the crank (3] lever.
Pull force (FP) is exerted by only cable A causes clockwise rotation of crank (3) lever. Hence upward rotation of crank (3) and trip shaft (2) is not sufficient for activation of the circuit breaker trip mechanism.

Pull force (FP] is exerted by only cable B causes anti-clockwise rotation of crank (3) lever. Hence upward rotation of crank (3) & trip shaft (2) is not sufficient for activation of the circuit breaker trip mechanism.
Pull force (FP) is exerted by cable A and cable B prevents any angular rotation of crank (3) lever. Combined pull force (Fp) of both cables (5) causes upward rotation of crank (3) and trip shaft (2) to a level sufficient for activation of circuit breaker trip mechanism.
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, 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 omission and substitutions of equivalents are contemplated as circumstance may suggest or render expedient, but such are intended to cover the application or implementation without departing from the spirit or scope of the present invention.

We claim:
1) A seesaw type interlocking arrangement for electrical devices comprising;
At least one crank with lever, the crank lever having plurality of circular holes at the centre and plurality of grooves along the surface of the crank lever;
At least one tripping shaft, the said tripping shaft passing through the circular holes of the said crank lever;
Plurality of cables, the said cables placed in cable guide and supported by cable mounting plate, the cables passing through the grooves along the surface of the crank lever;
Wherein, the pull force exerted by only one cable provides seesaw movement of the said crank without activating the trip shaft of the circuit breaker and the combined pull force of at least two cables moves the said crank upwards and rotates the trip shaft of the circuit breaker.
2) A seesaw type interlocking arrangement for electrical devices of the claim 1, wherein, the interlock mechanism provides ANDing of two incoming cables.
3) A seesaw type interlocking arrangement for electrical devices of the claim 1, wherein, interlocking prevents undesirable paralleling of the sources.
4] A seesaw type interlocking arrangement for electrical devices as described in any of the accompanying drawings.