FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
As amended by the Patents (Amendment) Act, 2005
&
The Patents Rules, 2003
As amended by the Patents (Amendment) Rules, 2006
COMPLETE SPECIFICATION
(See section 10 and rule 13)
TITLE OF THE INVENTION
A system for monitoring and controlling a plurality of street lights
APPLICANTS
Crompton Greaves Limited, CG House, Dr Annie Besant Road, Worli, Mumbai 400 030, Maharashtra, India, an Indian Company
INVENTORS
Nilesh Pundlik Gawali, Suresh Panditrao Waware from EDC Lab, CG Global R&D Centre, Kanjurmarg (East), Mumbai 400042, Maharasthra, India and Sanjay Laxmanrao Vyavahare from Lighting Division of Crompton Greaves Ltd , Kanjur (E), Mumbai 400042, Maharashtra, India, all Indian Nationals
PREAMBLE TO THE DESCRIPTION
The following specification particularly describes this invention and the manner in which it is to be performed.

FIELD OF THE INVENTION
This invention relates to a system for monitoring and controlling a plurality of street
lights.
BACKGROUND OF THE INVENTION
Street lights are found not only on city roads and highways, but also on college
campuses, around commercial and industrial centers, in public and private parks and amusement centers, and any other locations where safety of people and property is a significant concern.
Usually, a monitoring and controlling system is provided for a plurality of street lights, say eleven or more spread across a particular geographical location, to automatically control switching ON/OFF and varying the intensity of brightness of the street lights at pre-determined times. The heart of the monitoring and controlling system is a processor based controller interfaced to a power device such as a transformer supplying power to the street lights. The controller is pre-programmed, based on various inputs, to issue control signals to the power device to switch ON/OFF or vary the input supply voltage to the street lights. Depending on the configuration of the system, various other peripheral devices are interfaced with the controller such as sensors/devices for detecting the current status of the lamps i.e. ON or OFF, sensors for detecting the exact nature of the problem with the street lamps, timer devices and/or means for determining the current time etc. The controller may also be configured to communicate, either wirelessly or not, with another remotely located monitoring and controlling system for receiving either the control signals or input data for generating a control signal. Among the other input data used for automatically switching ON/OFF the street lights is the presence of sunlight. The presence of sunlight is usually detected by means of a Infra red (IR) sensor. The monitoring and controlling system is configured to fetch data from the IR sensor and upon no detection of IR

rays, the controller is pre-programmed to issue a control signal to power device to switch ON the street lights. However, the problem with such an arrangement is that, during overcast conditions in monsoon season, the visible spectrum of the sunlight is blocked and yet the IR rays are still detected. Ideally, since the visible spectrum is blocked, the street lights should come on which does not happen with the use of IR sensor.
Usually, the power device is a multi-tap step transformer through which the variation of supply voltage to the street lights is very coarse in the range of 20- 50 voltages. There is a need for fine variation in the range of 1-2 volts so as to achieve desired light level. Moreover, a sudden increase in the input supply voltage by 20% or more is immediately reflected on the output side also thereby increasing the chances of damages to street lights. There is a need to overcome such a scenario without using any separate surge protection device. OBJECTS OF THE INVENTION
An object of the invention is to provide a system for monitoring and controlling a plurality of street lights which automatically switches ON the street lights in overcast conditions.
Another object of the invention is to provide a system for monitoring and controlling a plurality of street lights through which a fine variation of the supply voltage to the street lamps may be achieved.
Another object of the invention is to provide a system for monitoring and controlling a plurality of street lights through which the street lamps are protected from a sudden surge of input supply voltage without using any separate surge protection device.

DETAILED DESCRIPTION OF THE INVENTION
According to the invention, there is provided a system for monitoring and controlling a plurality of street lights, the system comprising a micro processor based controller, at least one Infrared (IR) sensor interfaced with the controller for detecting IR rays from the sunlight, at least one Light Sensor interfaced with the controller for detecting visible spectrum of the sunlight, the street lights being configured to be provided power supply from an input supply line through a motorized auto-transformer driven by a motor, the motor being interfaced with the controller such that based on the signals received from the IR and Light sensors, the controller being preprogrammed to issue control signals to the motor to drive the motorized auto transformer accordingly to switch ON/OFF or vary the supply voltage to the street lights for switching ON/OFF or dimming/brightening the street lights.
These and other aspects, features and advantages of the invention will be better understood with reference to the following detailed description, accompanying drawings and appended claims, in which,
Fig 1 is a block diagram depicting a system for monitoring and controlling a plurality of street lights.
Fig 1 is a block diagram depicting a system for monitoring and controlling a plurality of street lights. The system comprises of a microprocessor based controller 1 held in a street light panel (SLP) and associated with a plurality of street lights, usually eleven. The system also comprises of at least one Infrared (IR) sensor 2, at least one light sensor 3 and at least one motorized auto-transformer 4 driven by a motor 5. The IR sensor 2, Light Sensor 3 and the motor 5 are interfaced with the controller 1 using well known interfacing protocols depending upon the type of the controller I. Usually, the controller 1 is a 32-bit embedded microprocessor such as

ARM CORTEX M3 loaded with an open source real time operating system such as freeRTOS. The readily available IR sensor 2 and a light sensor 3 are usually fitted atop the automation panel in a specially designed sealed enclosure, the installation site of the panel is carefully selected so as to avoid light directly coming on the sensor housing after the streetlights are turned on. The sealant used for the sensor enclosure is prepared with a desired opacity so as to enable light sensor sense the light properly. The Infra red (IR) sensor 2 detects IR rays from the sun whereas the Light sensor 3 detects the visible spectrum of the sun light between 600- 1000 nm (nano meter). The sensors 2 & 3 are connected to the controller 1 either through wires or wirelessly for transferring data therefrom to the controller I. The motorized autotransformer 4 is 270V auto transformer driven by an AC synchronous motor 5 for changing the ratio of the output voltage. The controller I is interfaced with the motor 5 through a relay in a know way using well known interfacing methods. Upon a control signal from the controller I, the relay is actuated to drive the motor 5 accordingly which in turn results in changing the ratio of the voltage resulting in varying the light output from the load, i.e. street lights 6, connected to the output end of the autotransformer 4.
The controller 1 is pre-programmed to issue control signals based on inputs from the sensors 2 & 3. For example, during normal day time when IR and visible spectrum of light rays from the sun are detected respectively by the IR 2 and Light 3 sensors, a control signal from the controller 1 is issued to motor 5 to drive the transformer 4 accordingly to stop power supply, if being supplied, to the street lights 6 thereby rendering them OFF. However, if an overcast condition develops during the day time and even if IR rays are detected by the IR sensor and visible spectrum of the sun light is not being detected by the Light sensor or is detected of a low

intensity (pre-decided), the controller 1 is pre-programmed to issue a control signal to the motor 5 to drive the transformer 4 accordingly to switch ON the power supply to the street lights 6.
According to another embodiment, the controller 1 of the above system is fed data pertaining to the current location of the controller. Alternatively, a GPS (Global Positioning) device may be interfaced with the controller I to determine the current location of the SLP during installation. Further astronomical clock data pertaining to the current location of the system is also fed into the controller 1. Astronomical clock data pertains to varying sunrise and sunset times everyday with respect to a location. The controller 1 is pre-programmed to automatically switch ON/OFF or vary the power supply to the street lights 6 based on the astronomical clock data and current system time. Normally, the current system time is available within the Operating System of the controller. Alternatively, the controller 1 may also be adapted to remotely communicate, either through wires or wirelessly through internet, web based or other known means, with another system/controller for receiving astronomical clock data or as a matter of fact the control signals which may be pre-programmed to override the control signals of the above system. Further, there may be other sensors made available in the system for detecting faults with the functioning of the system such as one for over current, demand controller, fire alarm etc. Intelligent sensors with a communication interface such RS485 can also be integrated to detect faults and any special signal level. Further, the controller t is preprogrammed to send SMS with fault details to a pre-decided recipient(s) as soon as the fault is detected, so as to enable the technicians to come prepared at the site location for rectifying the faults there by reducing the turn around time for fault rectification.
According to the invention, the street lights are automatically switched ON during overcast conditions. This is especially beneficial since most street lights are pre-programmed to

be switched ON/OFF only at a specific time and to switch ON/OFF them other than the predetermined times requires manual intervention and may not serve the purpose because of the fact the overcast conditions may be gone tiJl the time a person reaches a SLP to switch ON the street lights. The use of a motorized autotransformer allows fine variation of power supply to the street lights used for dimming/brightening them in the early hour's of the mornings/nights. Moreover, the use of motorized autotransformer enables detecting of short circuit within the system thereby eliminating the need of a special surge protection device. For example, whenever there is a short circuit within the system, the load current will start increasing exponentially while the input voltage is in the lower range of 20-30 volts. Under normal circumstances when there is no short circuit, the exponential rise in load current is only after the input voltage has reached 80 volts or more. Thus, a short circuit can easily be detected by use of the motorized auto transformer thereby eliminating the need of a special surge protection devic.
It is obvious to a person skilled in the art that the details of types of sensors, controller, interfacing protocols and methods, the underlying operating system within the controller and other such details may not be construed limiting.
Although the invention has been described with reference to a specific embodiment, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiment, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the scope of the invention as defined in the appended claims.

We claim: 1. A system for monitoring and controlling a plurality of street lights, the system comprising;
o a micro processor based controller;
o at least one Infrared (IR) sensor interfaced with the controller for detecting IR
rays from the sunlight; o at least one Light Sensor interfaced with the controller for detecting visible
spectrum of the sunlight; o the street lights being configured to be provided power supply from an input supply line through a motorized auto transformer driven by a motor, the motor being interfaced with the controller such that based on the signals received from the IR and Light sensors, the controller being pre-programmed to issue control signals to the motor to drive the motorized auto transformer accordingly to switch ON/OFF or vary the supply voltage to the street lights for switching ON/OFF or dimming/brightening the street lights.
2. The system as claimed in claim 1, wherein the motorized autotransformer is a 270V auto transformer driven by an AC synchronous motor for changing the ratio of the output voltage to the street lights.
3. The system as claimed in claim I, wherein the IR sensors detects IR rays from the sun and the Light sensor detects the visible spectrum of the sun light between 600- 1000 nm light rays from the sun.
4. The system as claimed in claim 1, wherein upon a predetermined low level detection of light rays from the sun by the Light sensor, irrespective of IR rays being detected or not,

the controller is pre-programmed to issue control signals to the motor of the motorized auto transformer to drive the transformer accordingly to switch ON the power supply to the street lights if OFF.
5. The system as claimed in claim 1, wherein the micro controller is an embedded controller based on a 32 bit processor such as ARM CORTEX M3 loaded with an open source real time operating system such as freeRTOS.
6. The system as claimed in claim 1, wherein the micro controller is adapted to receive control signals from a second monitoring and controlling system interfaced thereto through wires or wirelessly for switching ON/OFF or varying the supply voltage to the street lights.
7. The system as claimed in claim 6, wherein the second monitoring and controlling system is a remotely located web based monitoring and controlling system connected to the. said system through internet.
8. The system as claimed in claim 1, wherein the-controller is fed current location data of said system and astronomical clock data pertinent to the current location of said system and/or adapted to receive the current location data of said system through a GPS device or the second monitoring and controlling system interfaced thereto or through a second monitoring and controlling system.
9. The system as claimed in claim 9, wherein the controller based on the current time and astronomical clock data pertinent to the current location of the system issues control signals to the motor of the motorized auto transformer to drive the motor accordingly to switch ON/OFF or vary the supply to the street lights.

10. The system as claimed in claim 1, wherein at least one fault detecting sensor is provided interfaced with the controller for detecting a fault in functioning of the street lights.