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Discussion on several problems of anti-interference test of electronic weighing instrument
International recommendations published by International Legal Metrology Organization R76 "non-automatic weighing apparatus" for electronic weighing apparatus.Six electromagnetic compatibility performance tests, including: voltage sag, short interruption of the immunity, electrical fast transient pulse group immunity, electrostatic discharge immunity, surge (impact) Immunity, RF electromagnetic field radiation immunity, radio frequency field induction interference immunity and special EMC requirements for road vehicle power scales.
Maximum allowable variation
R76 requires its maximum allowable variation: in the case of interference and no interference, the indication change should not be greater than E, or the weighing instrument should be able to detect a significant increase in the difference and respond to it.
In response to this request, our country in revising the digital indicator scale national type evaluation outline, according to gb/t17626 "Electromagnetic compatibility Test and Test Technology" series of national standards, carried out detailed provisions:
In each anti-jamming performance test, the following conditions may appear, B, c) and D.
A) When the scale is subjected to interference, the change of indication value should not be greater than e in the interference and undisturbed condition;scale in the event of interference, temporary loss of function or performance temporarily reduced (such as: the value of the scale display flicker and cannot be read; The value of the scale appears to jump, even if the value change exceeds 1 E), but after the disturbance stops the scale self-recovery without operator intervention;
c) There is a significant increase in interference and no interference, but the scale appears sound, light alarm, and the situation the shape is consistent with the enterprise alarm description;
(d) Reduced functionality due to hardware or software damage, or data loss, that could not be restored to normal state or Loss。
Eligibility criteria: The test scale shall conform to the requirements of this outline, the present outline of a), b), C, is awarded as qualified,
D) and other circumstances are awarded as unqualified.2. Should the "non-automatic weighing apparatus" and "automatic weighing apparatus" be consistent?
In our international proposal from the International Legal Metrology Organization, it involves the total of weighing products: R76"Non-automatic weighing apparatus", R50 "continuous cumulative automatic weighing instrument", R51 "automatic inspection weighing instrument", R61 "Gravity type automatic loading weighing instrument, R106 "Automatic Railroad scale", R107 "discontinuous cumulative automatic weighing instrument", R134 "moving state road vehicle weighing and measuring axle load automatic weighing apparatus. These international recommendations have successively R76 "non-automatic weighing apparatus"
The contents of the EMC test have been introduced in their respective proposal documents. In addition, R60 weighing sensor
The international recommendations are also written: the weighing sensor with electronic components shall be given the electromagnetic compatibility performance and the range stability test according to the requirements.
Non-automatic weighing apparatus is a kind of in the weighing process needs the operator intervention, can determine whether the weighing result can acceptance of the weighing apparatus. And the automatic weighing instrument is a kind of in the weighing process does not need the operator intervention, can follow the preset the processing program automatically weighing the weighing apparatus.
In the weighing process produces the stronger electromagnetic interference, causes the weighing instrument which in the use to appear the big fluctuation,it may make the error of the weighing items bigger, not even normal weighing, but for the non automatic weighing apparatus,There is a chance that you can quit weighing again. Because the use of the weighing instrument in large fluctuations, can not be normal weighing, the value of the scale shows flicker and cannot be read, the value of the scale appears to jump;sound, light alarm. This will not affect the accuracy of the weighing.
For automatic weighing, it is not a phenomenon that can be ignored, it may directly affect the entire the operation of the system, such as "the ability to detect significant differences and to respond to them", affects the equipment reacts during automatic weighing to make the system stop. Whether the response is sound or light, the screen is black. For example, "continuous cumulative automatic weighing instrument (belt scale)" In terms of belt weigher is always installed in a material delivery system, once the belt scale is electromagnetic interference, the situation can not work properly, the entire material delivery system must follow the reaction, or even stop running, will inevitably bring irreparable loss to the system. For the belt weigher, the fluctuation of the weighing will affect the continuous cumulative quantity in addition to the instantaneous flow.
For some automatic weighing devices not used in the system, such as "Loader electronic scales",a significant increase in the difference will not affect the operation of other equipment, can completely relax the electromagnetic compatibility of such weighing apparatus requirements.
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