The flow totalizer controls the collection, display, control, remote transmission, communication, printing and other processing of various signals such as on-site temperature, pressure, flow, etc., and constitutes a digital acquisition system and control system, with liquid crystal and digital display, various external dimensions. It is suitable for flow measurement measurement control of various liquids, general gases, superheated steam, saturated steam; quantitative/batch control of media (with start, stop, clear function), with various flow sensors or transmissions It can be used in a variety of measurement and control applications.
1, the display value is unstable
The reason is that the line on the printed board that connects the power ground and the signal ground is too long, causing interference. At this time, connect the input low potential pin to the end of the ground to eliminate the influence of the ground line resistance.
2, the temperature drift is large
The temperature drift of the flow totalizer is extremely low, but many temperature drifts of the domestic flow totalizer are large, and those manufacturers are also afraid to talk about this problem. The flow meter temperature drift can be verified by this simple method: the flow totalizer is placed in an incubator at 40 ° C before use. After 2 hours, the displayed value is observed, and the value is displayed at room temperature. If the error is above 0.2%, the temperature drift is large. At this time, the corresponding processing can be performed according to the following reasons:
a, the drift of the input voltage, from the linearization circuit to find the cause.
b. The quality of the chip is unstable due to the A/D converter. Or the value of the external resistor and capacitor changes greatly, and the temperature drift of the regulated power supply is severe.
3, jumping words
When the flow totalizer is in use, the last digits of the jump range exceeds ±1 words, which is the skip word. The phenomenon of skipping is generally caused by the jitter of the input voltage. The input voltage is mostly from the linearizer. The input voltage of the linearizer can be measured by a five-and-a-half digit digital voltmeter. According to the jitter and the range of variation, check the regulated power supply. The operation of the regulator, and secondly check whether the integrated operational amplifiers in the stage are working properly.
4, the magnitude and actual difference
At this time, we must carefully check whether the setting parameters of the instrument are correct, check the measurement medium, compensation method and various parameters one by one, and then see if each type of signal input is normal.
5, the instantaneous amount of running a large number
In the field operation, the author has encountered a certain brand flow totalizer running twice, is the moment of recovery just after the power failure, after a while will automatically normal. Therefore, we must try to ensure that the instrument is powered normally.
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