An electric meter overcurrent protection method and overcurrent protection circuit
A technology of overcurrent protection and ammeter, applied in the field of overcurrent protection and circuit in ammeter, can solve the problems of small protection current limit, large influence of self-recovery fuse temperature, increase of test and design cost of ammeter, etc., to achieve simple implementation, Outstanding technical effect
Active Publication Date: 2018-05-15
CHONGQING HUAHONG INSTR
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Problems solved by technology
In these methods, if a self-recovery fuse is installed in the ammeter, it cannot be guaranteed that it can be disconnected every time an overcurrent situation occurs. There is still a maintenance current in the self-recovery fuse, and the self-recovery fuse is greatly affected by temperature. The higher the value, the smaller the protection current limit; and if an overcurrent protection circuit is added in the meter or a triode switch is used, the test and design costs of the meter will be increased, and in order to increase the overcurrent protection circuit, the circuit design in the meter will be will be more complicated
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[0016] refer to figure 1 , In one embodiment, the embodiment of the method for overcurrent protection of an ammeter in the present invention does not add any special overcurrent protection circuit, and the original circuit design of the ammeter is the most effective. Embodiments of the overcurrent protection method of the present invention include:
[0017] Step 1. Calibrate the resistance value in the ammeter, wherein the resistance value includes the resistance value of the sampling resistance and the voltage dividing resistance of the ammeter. According to the embodiment of the present invention, it is first necessary to ensure that the resistance value of the resistance in the ammeter is accurate, and to eliminate the error of these resistances, so it is necessary to calibrate the error of these resistances first, so that the resistance sampling is more accurate and the power control is more effective;
[0018] Step 2. On the basis of confirming the realization of step 1,...
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The invention provides an over-current protection method for an ammeter and an over-current protection circuit. Over-current protection can be achieved only by improving part of an existing circuit in the ammeter under the condition of not increasing any over-current protection circuit; meanwhile, effective control on a current in the ammeter is achieved; the over-current protection method for the ammeter comprises the steps as follows: resistance values in the ammeter are calibrated; the resistance value comprises the resistance value of a sampling resistor and the resistance value of a divider resistor of the ammeter; a load current I is obtained in the working state of the ammeter; and whether a power supply of the load is cut off or not is determined according to numerical comparison between the load current I and a preset current value I<MAX>. The over-current protection circuit for achieving the over-current protection method is provided in the embodiment of the invention.
Description
technical field [0001] The invention relates to the power collection technology of the power system, in particular to a method for overcurrent protection in an electric meter and a circuit for realizing the method. Background technique [0002] The overcurrent protection scheme in the prior art mainly adopts: a self-recovery fuse is used alone for overcurrent protection; the power protection chip in the overcurrent protection circuit in the ammeter is used for overcurrent output control, and the output will not be output when the current exceeds a certain value. Current; or set the triode switch, you can use the conduction characteristics of the triode, when the current exceeds a certain value, use the voltage drop generated on the connected resistor to turn on or off the triode. In these methods, if a self-recovery fuse is installed in the ammeter, it cannot be guaranteed that it can be disconnected every time an overcurrent situation occurs. There is still a maintenance cu...
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IPC IPC(8): H02H3/08
CPCH02H3/08
Inventor 杨志
Owner CHONGQING HUAHONG INSTR