How to test the metal float flowmeter?

Electromagnetic flowmeter manufacturers use the estimation method and instrumentation method, with GS8 check the sensor's excitation coil resistance, insulation resistance between power lines, grounding resistance and other items can meet the factory specifications, flowmeter converter zero point, output current, etc. can meet the accuracy requirements. Detailed inspection methods are.

(1) measure the resistance of the excitation coil to identify whether the excitation coil can have a short circuit between turns (test line number "7" and "8" between the resistance value), the resistance value should be between 30 ohms ~ 170 ohms. If the resistance is the same as the factory notes, the coil is considered excellent, thus indirectly reviewing the magnetic field strength of the electromagnetic flowmeter sensor has not changed.

(2) measure the excitation coil to ground (test line number "1" and "7" or "8") insulation resistance to identify whether the inductor can return to moisture, the resistance value should exceed 20 megohms.

(3) measure the electrical level and liquid touch resistance (test line number "1" and "2" and "1" and "3" ), indirectly review the electrical level, lining layer surface probably condition. For example, whether the surface of the electrical level and the lining layer can adhere to the stacking layer, and whether the stacking layer has conductivity or insulation. The resistance value between them should be between 1 kΩ~1 megohm, and the resistance values of line numbers "1" and "2" and "1" and "3 The resistance value of "1" and "2" and "1" and "3" should be approximately symmetrical.

(4) turn off the gate valve on the pipe, check the professional electromagnetic flowmeter in the case of full of liquid and liquid no activity of the whole machine zero point. Depending on the situation for appropriate adjustment.

(5) check the insulation resistance of the communication cable, excitation cable cores, check whether the shielding layer is intact.

(6) Apply GS8 calibration instrument to detect the output current of the converter. When zero flow is given, the output current should be: 4.00mA; when 99% flow is given, the output current should be: 20.00mA. The deviation of the derived current value should be better than 1.5%.

(7) detect the excitation electric value (between converter terminal "7" and "8"), the excitation electric positive and negative values should be in the standard range, about 137 (5%) mA.

Comment on the impact of the external environment of the flowmeter and on, such as the excitation line and power line with the same pipeline laying, excitation line and power line and high voltage cable in parallel, surrounded by large transformers or motors and other factors on the flowmeter operation accuracy of the termination of the review, this review key application of the estimation method, check the operation of the flowmeter has no sudden changes or fluctuations in the situation probably to identify the flowmeter has not been affected by electromagnetic waves or other stray waves or Whether there are air bubbles in the pipeline.

To the flowmeter itself, the apparatus and tools required for the test: GS8 a, 4-1/2 multimeter a, 500V megohmmeter a, pointer multimeter a and common tools.