Earthing of transducer
In order to make instrument work reliably, you increase accuracy of measurement and avoid interference of outside parasitic electromotive force, the transducer must be earthed alone and resistance of earthing is less than 10 ¦¸. When the pipe connected with transducer is painted with insulation material or non-metal, two sides of transducer must be installed with earthing rings.
1.Forms of earthing ring
A.General ring and PVC ring
Material: selected
Thickness: 5¡«12 mm
The earthing ring is for transducer with PTFE lining and is installed with flanges of transducer by way of screws, avoiding damage of transducer of lining's folding flanging(PTFE).
B¡¢Earthing ring with neck
Material: selected
Thickness: 5 mm
The earthing ring with neck is suitable for abrasive media such as mud, orepulp & coal liquid .Using the earthing ring with neck, you protect lining of transducer's two sides and last its life.
The earthing ring with neck must be ordered with transducer, otherwise the accuracy of flow -meter could be influenced in operation without earthing ring with neck.
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2.Ways of earthing
A.the transducer installed with metal pipe:If metal pipe interior without insulation coating, it is grounded as following figure.
B: The transducer installed with plastic pipe or pipe coated by insulation material or paint: The earthing ring must be installed between the two terminals of transducer and measured fluid in pipe becomes short circuit with earth, having zero voltage. Otherwise, electromagnetic flowmeter could not work normally.
Transducer installed in negative pole protection pipe
Transducer installed in negative-pole protection pipe: There is certain voltage difference between negative -pole protection and ground, therefore the measuraed media has very high common pattern earthing voltage. The transducer must be connected with earthing ring.
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1.Cable for ground appliance (installed under circumstances of larger interference outside) 2.Ground cable for transducer (equipped with flow-meter ) 3.You have to insulate earthing flange or earthing ring from flange connected with pipe. 4.Connection cable with area of 16mm? makes isolation between negative pole voltage & transducer. |
Note
1.The Earthing ring beside two sides of transducer must be insulated with flanges of pipe. The transducer is connected with earthing ring through ground cable 2. The material of earthing ring must bear the corrosion of measured media. The standard material of earthing ring supplied by manufacturer is 1Cr18Ni9Ti stainless Steel.
2.The flanges besides transducer's conduit are connected by copper conductor with area of 16 mm?, and forming a isolation between the negative pole protection voltage and transducer.For negative pole antirot protection is insulated with two connection pipes. In installation, notice following points:
¡ñBeing insulated with the flanges of pipe, the earthing rings must be installed beside flow-meter. The earthing rings, flow-meter and ground must be connected each other.
¡ñThe flanges of pipe must be connected by copper conductor and don't be connected with transducer by using copper conductor.
¡ñScrews for connecting flange must be insulated. Users must use cup and washer of insulation material.
| E-earthing ring 1¡¢flange of transducer 2¡¢lining 3¡¢hermetical ring 4¡¢flange of pipe 5¡¢screw 6¡¢nut 7¡¢washer 8¡¢insulated cup |
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Suggestion for installation
In order to avoiding measurement error by mixed up with gas and damage of PTFE and rubber lining by vacuum, see following as:
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