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19-01-2011, 04:44 PM
POWER LIMITER.docx (Size: 209.24 KB / Downloads: 101)
Electricity is one of the major sources of power in this world, but along with its utilization, a major portion of it is wastage and stealing. Electricity board is facing a lot of problem in conservation of electric power. We realized the problem and work over it. From this we got the inspiration to design a POWER LIMITER.
Earlier we were using fuse for protection from over- load, fuse is a device, which operates on overload (current). If the excessive current flows through the circuit then the fuse wire melts and it is to be replaced after every operation rating of fuse wire used.
To overcome the drawback of fuse, Circuit Breakers are used to break the circuit. . These are used in power grids substations and now a days miniature circuit breakers are used for domestic purpose. During overload it breaks the circuit by separating the moving contact. This moving contact is to be settled manually.
Circuit beakers are very common device being
used by electrical persons for switching ON/OFF the electrical loads. But the load switching is required automatically day or night, switching is required with respect to time period, switching is required with respect to applied load and all this continuously and automatically. An attempt is made to design such system, which would do above switching automatically. Such system would eliminate fuse links operators job to switch the load to ON/OFF at different time intervals etc hence we are designing a system which can perform all above mentioned jobs automatically and called as POWER LIMITER.
FEATURES OF POWER LIMITER:
Output power is limited to set watt.
Any attempt to draw more power results in flickering of lights.
Can be mounted any where on the electric line or on the electric post.
Helps in average billing.
Eliminates doubts of wrong billing.
This is feasible through power limiter of 200w/300w/400w etc up to 2000w and rating can be increased according to the requirement of consumer.
Can be made cheaper than ENERGY METER in large-scale production.
Avoids power thefts.
Provides SURGE PROTECTION to the load, which is not possible through energy meter.
Helps to limit farmers to draw power up to 5 to 10 BHP as per the permission granted.
Mechanical energy meters are not suitable for low power load as don’t work at such a low load. The sand particles get deposited on the spindle, which restricts the free motion of the wheel in mechanical energy meters.
Mechanical energy meters are viable for tampering and meter reading can be manipulated. Mechanical energy meters are costly and due to improper maintenances they get damaged.
We can also attach a LIGHT DETECTOR to POWER LIMITER to provide the supply only at night. Because there are lots of free consumers (i.e. single batti connection consumer). Which would give more finance to an electricity board?
Light is sensed by light detector and based on the presence/absence of light, the power is switched to load detector through the control block.
The load detector block compares the applied load with the set load and switches the load to OFF if the applied load is more than the set load and vice-versa. Power supply delivers the power to different blocks at different voltages.
Before the era of microprocessors, circuits were constructed using discreet logic like various gates, counters, flip-flop, decoders, monostable and registers. Circuit diagram was designed as per the requirement. Prototype PCB is made interconnecting the logic component as per the design.
Now a day we are having numbers of microprocessors, which can perform various arithmetic and logical operations as per the requirement of user. The microprocessor is a multipurpose, programmable, clock driven, register based electronic device, that reads binary instructions from s storage device called memory, accepts binary data as input and processes the data according to the instructions and provide result as output. Here we are using chip 89C51 (micro controller), which is more than sufficient, for most of the application.
Basically Electronic Power Controller is Based on Automatic Circuit Breaker. It is set For a particular power, which it checks time to time and operates the relay under abnormal condition. The following are the two conditions, which explains the working of electronic power controller.
1) ON SETTED LOAD (NORMAL CONDITION)
When there is no variation in the load, the load sensor senses and matches it with the sctted one IC 74 1 compare it with the reference (negative) voltage and ho ouffnit voltage is obtained at 741 IC i.e.,. zero output . Therefore, these is no triggering voltage to IC 555 but this IC 555 keeps on working as a timer and operate (he relay on normally closed condition and the supply in maintain.
2) ON HIGH LOAD (ABNORMAL CONDITION)
The load sensor senses the increased load and matches it with the setted load at preset. This is then compared with then reference (negative) I/P voltage of IC 741. The difference voltage is obtained at the output & this output acts as a triggering voltage & is given as I/P to IC 555. The output of IC 555 operates the relay and the supply to (lie load is disconnected.
Thus the circuit works under both the normal and abnormal condition.
The device has many application like preventing the power thefts in hostels, rented house etc. This can be used for average billing to the customers because he will be drawing only limited power and if the timer is also connected in series with this module then the power will be available for the limited time only.
The device can be made for different ratings of load, the cost of load sensor would be higher for higher rating of load. The flickering of load can be prevented by sensing and cutting off the load at very high speed so that eye can not recognize.
With the development of this module we could understand the intricacy of designing of circuit and its fabrication through PCB making , layout preparation artwork making etc. The use of 230V directly on the board requires the precaution else will lead to shock.
It is not possible to check the power consumption even if they do not pay the bill. Due to non payment of bill the service line can be disconnected but it would be very difficult to stop the hooking of LT lines.Meter reading in villages is very costly as the consumers are spread over a large area.
Meter reading is not required if power limiter is used. The single point consumer who have installed power limiters of 80/100 Watt can be charged monthly or tri-monthly. The single point consumers who have not installed these device and are taking power through hooking can be noticed from outside can be penalized/punished .It is not required to go inside the houses. A team of 2-3 inspection engineers can check 100-200 connections every day. Since these single point connections would deliver power in night only it would provide 500 to 550 M Watt excess power in day time, which would give more finance to a electricity board whose free consumers are around 22 lakhs.