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НаименованиеThe TARAN-T Intelligent Heatmeter and Flowmeter

 

This article describes the practical use of industrial controllers in the TARAN-T heatmeter.

The company Flow Spectr produces the TARAN-T, a flowmeter to measure the amount of a liquid and temperature. The device measures the pulses of eddies created in the liquid flow by an obstacle such as a prism, converting the pulses into an electric signal used to determine the speed and flow of the liquid through a pipe. The conversion method is particularly critical to the accuracy and reliability of the device, the types of flows that can be measured and the configuration of the hardware.

Usually such conversion is done using a piezoelement sandwiched between two plates. However, the TARAN-T works based on the principle that a current will pass through a conductor flowing through a magnetic field. Water is the conductor, heat-resistant magnets create the magnetic field, and a pair of electrodes in the water pick up the electric signal. Due to the weakness of the signal, spectral analysis is used as the means of measurement.

The spectrum of the signal generated by the eddies in the flowmeter ranges from 1 hertz to a little more than 1 kilohertz. This makes it possible to use popular low-power processors such as the 1801BM2 or i8088, and the controllers in our first heatmeters used the 1801BM2. However, we subsequently sought an affordable, more reliable, IBM PC-compatible solution that would be capable of operating in conditions of high temperature and heavy vibration.

We selected the 6012 controllers from Octagon Systems' MicroPC line, which included an eight-channel analog-to-digital converter and a digital input/output port. Octagon Systems was also able to provide almost everything else we needed to build the controller. To date we have installed several dozen of the TARAN-T heatmeters using the MicroPC.

On the whole, the 6012 controller has proved up to the job. However, we continue to put new demands on the hardware, such as using one controller to monitor two heat systems or using a nonstandard configuration for the heatmeter. These and other new demands are testing the limits of the processor and the signal processor. The new 6040 microcontroller from Octagon Systems could address these issues. If the required device does not have to meet the strict reliability and environmental requirements, hardware from Advantech and M-Systems could provide a less expensive solution.

The use of analog signals to move information has resulted in a great number of cable connections, which in turn requires additional measures to prevent interference and makes it more difficult to diagnose malfunctions. For this reason, Flow Spectr is developing a system in which signals are processed within the initial converter, while the information is relayed to the controller through a single RS-485 connection.

A screenshot of the display and the regulator control process. 

The primary converter on a 32 mm flowmeter
 

By Igor Biryukov

Igor Biryukov