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Electromagnetic flowmeter signal
Electromagnetic flowmeter signals, electromagnetic flowmeter after the installation of no maintenance of the premise condition can be all normal operation for a long time, later must be maintained and checked.Sometimes also can appear electromagnetic flowmeter small signal condition, so there is no need to surprise, carefully do the following process can be met and solved.
1. Mechanism of small signal
Electromagnetic flowmeters are subject to deviations and are highly susceptible to interference, such as "small signal" conditions, in specific precise measurements on the spot and in production processes.According to the principle of electromagnetic flowmeter, the interference problem of electromagnetic flowmeter is caused by various excitation methods.
At present, many processing plants have the following problems:
(1) when the pump is started, the liquid is laser-cut through the magnetic induction line according to the flowmeter, resulting in the flow signal. This liquid is used in the later stage. The measured flow value is reasonable, and the total should be carried out;When the pump stops, there will be a small amount of liquid flow back in the pipeline, cutting the magnetic induction line in the opposite direction, which will also cause a small signal, but the liquid has not been specifically made use of, and the steam flow meter will still transmit the signal to the PLC for sampling total, which will lead to a large deviation.
(2) because of external vibration or large magnetic field interference, when there is no material flow, external vibration and other signals function in the controller, and "error flow" signals are imported. When such signals are higher than the low limit of measurement on the dashboard, they are also summed up.
(3) the surface of the electrode is attached to a layer of insulation, suffers from external interference or the mAh signal sent by the electrical level appears zero shift in the process of growing and transforming, which causes the signal to shift the standard value, thus resulting in deviation.
All of these conditions are classified as small signal conditions.
2. Small signal solutions
The small signal problem caused by the interference signal can not be dealt with from the process technology, only from the process control level to find the processing method.Can according to hardware and mobile phone software two methods to deal with.
The hardware configuration method can be composed of more power supply circuits and electronic switches. This method is suitable for filtering out interference signals, but it will increase the company's product cost. Since there are many flowmeters in a section length, it is relatively necessary to replace many such meters.
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