FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
As amended by the Patents (Amendment) Act, 2005
AND
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2005
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
Sensing systems for sensing fluid measurement in a housing
APPLICANTS :
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTOR (S):
Singh Aditya, of Crompton Greaves Ltd, Transformer (T3) Division, Plot No 29, 31 and 32, New Industrial Area No 1 AKVN, Manideep, 462046, Madhya Pradesh, India; an Indian National.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of this invention and the manner in which it is to be performed:

Field of the Invention:
This invention relates to the field of electronic systems.
Particularly, this invention relates to the field of sensing systems.
Still particularly, this invention relates to sensing systems for sensing fluid measurement in a housing.
Background of the Invention:
A conservator, typically, refers to part of an oil-filled transformer where oil is stored. An associated transformer may utilize the oil since its windings are immersed in oil. It is necessary to monitor the level of oil in the conservator in order to understand the requirements to fill when necessary for unhindered running of the transformer.
In similar analogous equipment, it may be necessary to monitor fluid levels in a housing. The monitoring, according to a good working condition, should be precisely indicative.
Currently, magnetic oil gauges which use float arms to check the level of oil are used. As the level varies, the float arm moves with respect to a float placed on the water surface. The float arm is connected to an interpretation calibrated means adapted to provide a calibrated reading of the level of oil.

This is typically a mechanical assembly, hence plagued with lag in time relating to mechanical translation of motion. Also, mechanical assemblies are not highly sensitive and come with an inbuilt level of play and tolerance or error factor. Further, the assembly does not provide reading below a certain level, thus obviating minimal readings at the bottom.
Hence, there is a need for a sensitive and precise measurement means.
Prior Art:
US7819003 discloses a system for remote monitoring of fluid storage tanks. In a most basic embodiment, an interior sensor system is arranged on a housing of the storage tank or other fluid-storage structure and is arranged to obtain information about any fluid in the interior of the housing, this information being the presence of fluid in the tank and/or the level of fluid in the tank
EP0441050 discloses a method for sensing temperature, pressure and liquid level, and variable ratio fiber optic coupler sensors therefor. A method of sensing a parameter in an environment subject to spark hazard utilizing at least one fiber optic coupler sensor, each said sensor having a plurality of input optical fibers each having a core, said cores of said optical fibers being merged and fused in a waist region to form a common optical core wherefrom a plurality of output optical fibers emerge, said fiber optic coupler sensor distributing light energy incident to one of said input optical fibers between said plurality of output optical fibers, said waist region being encapsulated in an encapsulating material having a refractive index variable with stress applied thereto such that said incident light energy is

distributed between said plurality of output optical fibers as a function of stress applied to said encapsulating material; comprising the steps of: positioning said fiber optic coupler sensor within said environment to sense said parameter, said stress being generated in said encapsulating material by said parameter, and converting said distributed light energy emerging from said output optical fibers into corresponding electrical signals, thereby sensing said parameter.
Here, continuous accurate measurement with avoidance of false readings is not provided.
US6831290 discloses an Electro-optic fluid quantity measurement system. A system for measuring a level of a fluid, comprising: a light source adapted to generate light having a predetermined wavelength; an optical waveguide slab at least partially filled with a material adapted to fluoresce when illuminated by the light having a predetermined wavelength; a first optical fiber in optical communication with the light source; a waveguide housing mechanically coupled to the first optical fiber; a light pipe mounted in the waveguide housing and being in optical communication with the first optical fiber, the light pipe being adapted to transmit the light having a predetermined wavelength to the optical waveguide slab at an angle that causes the light having a predetermined wavelength to be internally reflected only within a portion of the optical waveguide slab located above the fluid thereby illuminating the fluorescent material within the portion of the optical waveguide slab located above the fluid; a second optical fiber mechanically coupled to the photo-multiplier tube and in optical communication with the optical waveguide slab; and a photo-multiplier tube in optical communication with the

optical waveguide slab and adapted to generate an electrical output in response to the fluorescence of the fluorescent material.
Instead of sensor pairs, an optical waveguide slab is used. The light pipe transmits the light to the optical waveguide slab which reflects the light only within a portion of the optical waveguide slab located above the fluid. False and insensitive readings is a probability with this system and method.
There is a need for a precise and real-time sensing system for fluid levels stored in a housing.
Objects of the Invention:
An object of the invention is to provide a precise and real-time sensing system for fluid levels stored in a housing.
Another object of the invention is to provide a fluid level sensing / measurement system with no false positives or no false readings.
Yet another object of the invention is to provide a fluid level sensing / measurement system.
Still another object of the invention is to provide a fluid level sensing / measurement system which measures an entire range of fluid in a housing.

An additional object of the invention is to provide a fluid level sensing / measurement system which measures even low or minimum levels of fluid in a housing.
Summary of the Invention:
According to this invention, there is provided a sensing system for sensing fluid measurement in a housing, said system comprises:
a. multiple pairs of sensors, placed operatively one below the other, consisting
of emitters and corresponding receivers with emitters placed on a first wall
and corresponding receivers placed on a second opposing wall at
corresponding heights, each of said emitter-receiver pair operating at a
defined frequency, different from each of other pairs, wherein said sensor
pair is activated when level of fluid falls below said sensor pair, thereby
completing the circuit of receiving without fluid interference; and
b. processing unit adapted to receive sensed output upon a specific sensor pair
activation based upon height of said fluid for providing a reading of fluid
level based on calibrations done in accordance with pre-defined
measurements.
Typically, a train of emitters are placed operatively one below the other on said first wall
Typically, a corresponding train of receivers are placed operatively one below the other on said second wall.

Typically, said system includes a configuration means adapted to configure each pair, corresponding to a pre-defined frequency, with the processing unit.
Preferably, said sensors are TSOP Sensors.
Preferably, said emitter is a LED.
Preferably, said receiver is a photo diode.
Typically, said system includes a display for displaying said reading.
Brief Description of the Accompanying Drawings:
The invention will now be described in relation to the accompanying drawings, in which:
Figures 1 and 2 illustrate a schematic of the system.
Detailed Description of the Accompanying Drawings:
According to this invention, there is provided a sensing system (100) for sensing fluid (300) measurement in a housing (200).
Figures 1 and 2 illustrate a schematic of the system.

For the purposes of this specification, the fluid is oil and the housing is an oil conservator.
In accordance with an embodiment of this invention, there is provided a first pair of sensors (10, 12), said pair including an emitter and a transmitter, operating at a first frequency. The first pair of sensors is placed at pre-defined locations on opposing walls, i.e. an emitter is placed on a first wall (40) and a transmitter is placed on a second opposing wall (50) at the same height. As the fluid between said walls reaches the level between first sensor pair, the sensors activate to provide a sensed output. Calibrations, in accordance with pre-defined measurements are done at a processing unit (14). This calibration provides the reading.
In accordance with a further embodiment of this invention, there are provided multiple pairs of sensors (16-18, 20-22, 24-26, 28-30, 32-34) which includes complementary emitters and transmitters at various heights, at corresponding frequencies.
Typically, a train of emitters are placed operatively one below the other on said first wall and a corresponding train of receivers are placed operatively one below the other on said second wall. One pair corresponds to one height measurement and therefore corresponds to one calibrated reading.
Each pair corresponds to a pre-defined frequency which is configured with the processing unit. Thus, when liquid level is in line with a specific sensor pair, the

particular frequency level is activated, and hence, the processing unit senses the specific frequency in order to provide a related calibrated reading.
Preferably, the sensors are TSOP Sensors. The TSOP (Thin Small Outline Package) is a general purpose proximity IR sensor. Here, it is used for fluid level detection. The module consists of an IR emitter and TSOP receiver pair. The high precision TSOP receiver always detects a signal of fixed frequency. Due to this, errors due to false detection of ambient light are significantly reduced.
The output of TSOP is high whenever it receives a fixed frequency and low otherwise.
The transmitter sends out light in pulses. These are translated into binary codes that have corresponding commands. The infrared receiver is positioned in front of the apparatus, where it receives these pulses of light and then decodes them into binary data understood by the processing unit (microprocessor) inside the system. The processing unit then translates the data into specific commands which it goes on to implement. In this case, the Microprocessor is simulated to specify the fluid level in the conservator.
Transmitter is, typically, made of LED (Light Emitting Device), receiver is, typically, a Photo Diode (which conducts only when light is incident on it). TSOP is also an IR sensor but differs from phototransistor in following aspect:
1) Output is 0 or 5 V
2) Responds only to IR pulses of range 33 KHz to 40 KHz

Infrared Light undergoes refraction when they travel through fluids and the Angle of Refraction is determined by the refractive index of the fluid through which the rays are travelling. In case of fluid between The Emitter Receiver pair, Infrared rays get refracted and hence the diametrically opposite situated sensor does not receive the signal indicating presence of fluid in between.
In case there is no fluid present between a particular emitter receiver pair, the photo-diode gets activated, thus sending the signal to the processing unit.
The TSOP sensors of difference frequencies are used to avoid the refracted rays of Non diametrically Opposite side to reach the Photo Diode and hence avoid provising a wrong signal.
TSOP corresponding to different frequency ranges are available.
e.g. TSOP 1736 - responds to pulses at 36 KHz and TSOP 1738 responds to 38
KHz
Signal corresponding to each Emitter Receiver pair can be detected using a processing unit and corresponding Oil Level can be displayed on a display (55).

We claim,
1. A sensing system for sensing fluid measurement in a housing, said system
comprising:
a. multiple pairs of sensors, placed operatively one below the other,
consisting of emitters and corresponding receivers with emitters placed
on a first wall and corresponding receivers placed on a second opposing
wall at corresponding heights, each of said emitter-receiver pair operating
at a defined frequency, different from each of other pairs, wherein said
sensor pair is activated when level of fluid falls below said sensor pair,
thereby completing the circuit of receiving without fluid interference; and
b. processing unit adapted to receive sensed output upon a specific sensor
pair activation based upon height of said fluid for providing a reading of
fluid level based on calibrations done in accordance with pre-defined
measurements.
2. A system as claimed in claim 1 wherein, a train of emitters are placed operatively one below the other on said first wall
3. A system as claimed in claim 1 wherein, a corresponding train of receivers are placed operatively one below the other on said second wall.
4. A system as claimed in claim 1 wherein, said system includes a configuration means adapted to configure each pair, corresponding to a predefined frequency, with the processing unit.

5. A system as claimed in claim 1 wherein, said sensors are TSOP Sensors.
6. A system as claimed in claim 1 wherein, said emitter is a LED.
7. A system as claimed in claim 1 wherein, said receiver is a photo diode.
8. A system as claimed in claim 1 wherein, said system includes a display for displaying said reading.