FIELD OF INVENTION:-

The invention relates to an improved change over switch and more particularly to a high speed change over switch for rotating main motor generator while transition from normal to emergency mode by sensing the degradation in voltage or frequency.

2)BACKGROUND OF THE INVENTION:

High Speed Change Over System (HSCOS) senses the changes in input voltage and frequency from their normal range and implement the transition from normal to emergency mode for Rotating Main Motor Generator (RMMG). HSCOS consists of a microcontroller board based on ARM Cortex-M3 Microcontroller. Sensing is carried out for two signals and namely voltage and frequency. There are three microcontroller modules which are enclosed in an enclosure. The three modules monitories the three phase voltages and the outputs of the three boards are connected to a majority gate for implementing the 2/3 logic. It uses the Triple Modular Redundant technology (TMR) to see if two or more microcontroller board senses the fault, then only the relay is tripped.
Conventional Automatic change over systems detects only amplitude of the signal and switches between main power and backup power sources.
According to US Patent US57566345A, an improved changeover relay and more particularly to an automatic relay adapted to quickly change over from a main source of power to a spare source of power. Certain heavy aircrafts are equipped

with a main inverter and a spare inverter for producing alternating current for electrical circuits particularly connected with the control of superchargers for the aircraft engines. Certain of these circuits at present require the use of 115 volt,400 cycle alternating current. The inverter used to produce this current is a motor generator set comprising a 26-volt direct current motor coupled to a 115volt, 400 cycle alternating current generator. The main inverter or generator provides the power for the alternating current control circuits, except in the case of its failure. It is extremely important in the case of such failure to immediately start the spare inverter so that the 115-volt current is continued with as little interruption as possible.
US patent US611783454, teaches an automatic control change-over relay system that includes a time-delay relay, an A. C. relay, and a D. C. relay, as in the case of the system disclosed in the above mentioned application, but these relays are interconnected by distinctly different circuits to accomplish the features and objects of the present invention. The relays are connected in such a way that when the pilot closes the main switch to start the main inverter, it r and not the spare inverter is energized. Furthermore, the circuits connecting the various relays of the system are arranged so that a momentary interruption, or drain on the main inverter or on the D. C. current, does not cut in the spare inverter, but sets up a circuit which would eventually cut in the spare inverter if an interruption or drain continues beyond a predetermined time. Analog circuit is used for energizing and de energizing relays.
The need exists for sensing both the amplitude and frequency of the voltage simultaneously from the source and generating a relay output(fault) for changing from one source to another source within 50 ms.
The need exists for a system which is highly reliable hence TMR (triple modular redundancy) logic is used, where three sensing circuits are used for sensing the

voltage and frequency and the output will be generated only when two out of three circuit gives the fault.
3) OBJECT OF THE INVENTION:
It is therefore an object of the invention to implement transition from normal to emergency mode for Rotating Main Motor Generator(RMMG).
Another object of the invention is to sense voltage and frequency simultaneously.
Another object of the invention is using Triple Modular Redundancy(TMR) logic for high reliability.
Another object of the invention is to provide high speed response in sensing the degradation in voltage and frequency.
Yet another object of the invention is to provide accuracy with which the system senses voltage and frequency.
4) SUMMARY OF THE INVENTION:
High speed change over system (HSCOS) senses the changes in input voltage and frequency from their normal range and implement the transition from normal to emergency mode for RMMG. High speed change over system consists of microcontroller board based on ARM microcontroller. There are two types of signals sensed namely voltage and frequency.
There is a predefined limit for voltage and frequency, once the voltage or frequency crosses the limit the ARM processor generates an error signal. There

are three processors which continuously monitors the voltage and frequency circuit, the output of the three processors are connected to a Triple modular circuit (TMR) which is a majority gate so if two or three processors generates an error signal then only the final output will be declared as error signal.
5) BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS: -
FIG. 1 shows an overall view of the High Speed Change Over System in accordance to the invention.
FIG. 2 shows a ARM processor based module in accordance to the invention.
61DETAILED DESCRIPTION OF THE INVENTION:
The invention improves upon existing automatic change over switch for the changes in input voltage and frequency from their normal range and implement the transition from normal to emergency mode for RMMG. As shown in FIG. 1, the High Speed Change Over System (HSCOS) of this invention is referred generally by the reference numeral 1 and includes an ARM processor based module B, 9 and 10 which is the ARM processor based module (12) of FIG 2 and voltage sensor (5, 6 and 7).
As shown in FIG. 1, the feeder lines R- phase (2) and Y-phase (3) are connected to the voltage sensor (5). The output of the voltage sensor (5) is connected to the ARM processor based module (8), The feeder lines Y- phase (3) and B-phase (4) are connected to the voltage sensor (6). The output of the sensor (6) is connected to the ARM processor based module (9). The feeder lines R- phase (2)

and B-phase (4) are connected to the voltage sensor (7). The output of the sensor (7) is connected to the ARM processor based module (10).
There is an interconnection among the three ARM processor based modules (8,9)- and(10) for implementing the Triple Modular Redundancy (TMR) logic. The final potential free output (11) of the system l is depicted.
FIG. 2 shows the ARM processor based module (12) of FIG. 1(8, 9)and (10). The input current signal (13) from the voltage sensor is converted into voltage signal by the signal conditioning circuit (14). The signal conditioning circuit (14) consists of a burden resistor and low pass filter for converting the current signal into voltage signal. The voltage signal then passes through a gain circuit which is used for amplifying the voltage signal.
The output of the signal conditioning module (14)is connected to the RMS to DC converter (17) and the zero crossing detector module (15). The output of the RMS to DC converter (17) is the RMS value of the voltage coming from the signal conditioning module (14).
The output of the RMS to DC converter (17) is scaled down to voltage of 0-3. 3voltsusing scaling circuit and given to the analog input of the ARM processor (18)where the voltage is calculated.
The zero crossing detector (15) takes the input as sine wave and generates the output square wave which goes to digital input of the ARM processor (18) where the frequency is calculated.

There is a predefined limit set for the voltage and the frequency in the ARM processor (18) and whenever the calculated voltage and frequency crosses the predefined limit the ARM processor (18) generates an error signal which is passed to the op to-isolated digital output circuit (16) and thereafter to the TMR circuit(20).
The TMR circuit (20) is a gate circuit which receives input from the other two ARM based modules (8and 9) of FIG-I. If two out of three signals are high which means error to the input of TMR circuit (20) ,then the output of the TMR circuit (20) is high .The relay driver (21) drives the relay (22) due to which the output(l 1) of Fig. 1 is changed from NC to NO position in less than 50 ms.
The sine wave of 50 Hz has time of 20 ms for one cycle. The output of zero crossing detector (15) is square wave with 10ms of width in high position and 10ms of width in low position so for calculating the frequency it takes around 12ms, voltage (RMS value) around (25) ms and relay has a delay of 10 ms. Hence it takes less than 50 ms to implement the transition of RMMG from normal to emergency mode.
Thus it can be seen that the invention accomplishes at least all of its stated objectives.

We claim; -
1. A high speed change over system (HSCOS) to detect AC supply deterioration
in a rotating main motor generator (RMMG) comprising
- a feeder line R phase (2) coupled to a voltage sensor (5) which is coupled to a ARM processor module (8) and a voltage sensor (7) that is coupled to a ARM processor module (10);
- a feeder line Y phase (3) coupled to a voltage sensor (5) which is coupled to a ARM processor module (8) and a voltage sensor (6) that is coupled to a ARM processor module (9);
- a feeder line B phase (4) coupled to a voltage sensor (6) which is coupled to a ARM processor module (9) and a voltage sensor (7) that is coupled to a ARM processor module (10);
wherein the three ARM processor module are interconnected and generates an output signal;
wherein the output signal is fed into a signal conditioning module (14) coupled to further associated eclectic devices to analyses the signal in terms of voltage and frequency and generate an error signal when two of t a three sensing circuit determines faulty condition.
2. The high speed change over system (HSCOS) to detect AC supply deterioration in a rotating main motor generator (RMMG) as claimed in claim 1, wherein the inter connection of the ARM processor modules implements the Triple Modular Redundancy (TMR) Logic.
3. The high speed change over system (HSCOS) to detect AC supply deterioration in a rotating main motor generator (RMMG) as claimed in claim 1,comprising a TMR circuit (20) to receive input from ARM based modules (8) and (9) in which the input signal is high the error signal is high.



4. The high speed change over system (HSCOS) to detect AC supply deterioration in a rotating main motor generator (RMMG) as claimed in claim 1, as illustrated in the accompanying drawings.
5. The high speed change over system (HSCOS) to detect AC supply deterioration in a rotating main motor generator (RMMG) as claimed in claim 1, wherein the associated electronic devices are DC converter (17), zero crossing detector module (15) and ARM processor (18).