Electricity: measuring and testing – A material property using electrostatic phenomenon
Patent
1997-11-13
2000-02-29
Do, Diep N.
Electricity: measuring and testing
A material property using electrostatic phenomenon
324457, 340562, G01R 2912
Patent
active
060313781
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND AND SUMMARY OF THE INVENTION
The present invention relates to a measuring system and a method of detecting static electricity in a measuring object or test material as described more in detail in the preamble of the appended independent claims. The invention also relates to the use of the measuring system.
The above mentioned measuring system typically includes at least a sensor, a voltage meter and a processor unit with a signal processing unit connected to the voltage meter. The sensor of the measuring system comprises a sensing element, such as an antenna or an electrode, arranged so that the electric field of the measuring object or test material induces an electric signal in the sensing element indicating a change in electric charge which is proportional to the electric charge of the measuring object or test material. A detector is connected between the sensing element and the voltage meter. The detector consist typically of a capacitor circuit connected between the sensing element and the voltage meter, which transmits to the voltage meter the signal indicating a change in electric charge induced in the sensing element.
Simple reliable systems of this type suitable also for industrial processes have not as yet been available on the market.
A measuring system for measurement of electric charge in turbulent material flowing through a pipe, so as to find out the risk of explosions in the material, has been suggested in U.S. Pat. No. 3,753,102. Variations in the electric charge of the turbulent material which flows past an electrode are measured with an AC voltage meter. The AC component induced by the changes in the electric field is conducted directly via an AC amplifier and a rectifier to a DC voltage meter. The measuring system seems to be very sensitive, and requires protection against interference from external electric fields.
U.S. Pat. Nos. 4,370,616 and 5,151,659 disclose similar measuring systems with direct measurement of electric charges, in this case induced in rapidly oscillating electrodes arranged in a protecting opening in front of the surface the charge of which is to be measured. The measuring signal is amplified in an amplifier before the voltage meter. Even this measuring system is sensitive to interference. The measuring signal and all interference signals, if any, are amplified and read off.
U.S. Pat. No. 4,716,371 and British Patent Specification No.1 568 811 disclose similar measuring systems with capacitive circuits. These measuring systems seem to be highly sensitive to interference.
It is an object of the present invention to provide a new, reliable and as to its design simple measuring system for detecting electric charges in e.g. flowing powdery mediums, gas flows, or material webs in various kinds of processes, in order to obtain measuring values which can be used for controlling these processes.
It is a particular object of this invention to provide a measuring system and a method which is also suited for use in industrial processes under severe, e.g. dust-laden and/or interference-laden conditions.
It is a further object of this invention to provide a measuring system having an amply sufficient sensitivity to signals of low frequencies, e.g. in the order of 1-10 Hz.
It is a further object of the invention to provide a measuring system in which the influence of interference can be minimized.
The above stated objects are achieved by means of measuring systems and methods which are characterized by what have been stated in the characterizing part of the appended independent claims.
A measuring system according to the invention includes in the detector a capacitive or capacitor circuit having an integrating effect on the measuring signals which are conducted via the detector from the sensing element, i.e. the antenna or electrode, to the voltage meter. The measuring values from the voltage meter are processed and evaluated in an processor unit.
According to a preferred embodiment of the invention a resistor R is connected in parallel to the capacitor circuit havin
REFERENCES:
patent: 3863241 (1975-01-01), Kamiyamaguchi
patent: 3935532 (1976-01-01), Shuey et al.
patent: 3943437 (1976-03-01), Mourier
patent: 4063154 (1977-12-01), Andrus et al.
patent: 4613228 (1986-09-01), Suzuki et al.
patent: 4716371 (1987-12-01), Blitshteyn
patent: 4740862 (1988-04-01), Halleck
patent: 5019804 (1991-05-01), Fraden
Do Diep N.
TR-Tech Int. Oy
LandOfFree
Measuring system and a method for detecting static electricity a does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Measuring system and a method for detecting static electricity a, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Measuring system and a method for detecting static electricity a will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-686324