Experience in Using a REP-1M Pulse Controller to Regulate the Temperature of the Working Space of a Glass-Melting Furnace
Abstract Generated abstract
This paper reports an industrial trial of a REP-1M pulse controller for automatic regulation of the working-space temperature in a glass-melting furnace. Because the standard controller dead zone was too large for the required temperature accuracy, the authors introduced a preliminary amplifier between the measuring instrument and controller and describe the resulting control scheme and amplifier circuit. Tests at the Tomsk Electric-Lamp Plant, where the furnace had an experimentally determined time-constant ratio of about 1.1, showed that an amplifier gain of 10 reduced the effective controller dead zone to about 1.0 to 1.6 degrees C and enabled regulation within approximately 1 percent of the instrument scale, although temperature disturbances remained due to a nonautomated flame-reversal system.
Full Text
EXPERIENCE IN USING A REP-1M PULSE CONTROLLER TO REGULATE THE TEMPERATURE OF THE WORKING SPACE OF A GLASS-MELTING FURNACE
A. A. Gurchenok, V. D. Serebrennikov, Yu. M. Trifonov, A. F. Fedorov
(Presented by Professor G. N. Kokom)
When selecting the type of controller, if the value of the ratio
\[ \frac{\tau}{T} > 1 \]
one should use a pulse controller [1]. The existing standard REP-1M controller, with a 20% rheostat sensor, has a dead zone of 0.6–1% of the maximum value of the measuring instrument scale [2], which leads to considerable errors, in some cases inadmissible according to technological requirements. The use of a REP-1M controller becomes possible when a preliminary amplifier is used (Fig. 1), with a gain coefficient determined by the required accuracy conditions.
Fig. 1. Block diagram of temperature regulation:
1 — controlled object;
2 — potentiometer;
3 — preliminary amplifier;
4 — controller;
5 — regulating element.
A similar scheme was tested for regulating the temperature of the working space of a glass-melting furnace at the Tomsk Electric-Lamp Plant.
The average value of the ratio \(\frac{\tau}{T}\) for the furnace, according to experimental data, is equal to 1.1. The REP-1M pulse-action controller operates jointly with an ETP-120 measuring instrument with a 20% rheostat sensor; the operating temperature \((1683^\circ\mathrm{K})\) must be maintained with an accuracy of \(\pm 15^\circ\).
It is obvious that the use of the REP-1M controller without preliminary amplification is not possible, since the required accuracy is less than the dead zone.
According to the operating conditions, the preliminary amplifier (Fig. 2) must operate without distortion at both large and small mismatches, since its load is the input transformer of the controller, which must not be loaded with direct current.
Diodes D4, D3 serve as signal limiters.
Figure 3 shows diagrams for automatic and manual temperature regulation. As can be seen from the diagram, the temperature pro-
Fig. 2. Schematic diagram of the preamplifier: D1–D2—D101 diodes; D4–D3—D9E diodes; PP1—P4B triode; C1—EGTs-1000 capacitor, 1000 μF—30 V; C2—ETO capacitor, 50 μF—30 V; R1—PEV, 7.5–230 ohms; R2—MLT-0.5, 24 kΩ; R3—MLT-0.5, 1 kΩ.
Fig. 3a. Diagram of the recording instrument under manual temperature control.
... of the process was maintained with an accuracy of ±15°C. Periodic temperature jumps were caused by the irregular operation of the flame-reversal system. The flame-reversal system was not automated.
Fig. 3b. Recorder chart under automatic temperature control.
Conclusions
The use of a preliminary amplifier with an amplification factor \(K = 10\) reduced the dead zone of the controller itself to 0.06–0.1% of the maximum value of the measuring-instrument scale, which in the case under consideration amounted to \(1.0 \div 1.6^\circ\mathrm{C}\).
The use of pulse controllers of the REP-1M type at
\[ \frac{\tau}{T} > 1 \]
is expedient and made it possible in our case to carry out regulation with an accuracy of 1% of the instrument scale.
LITERATURE
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V. S. Prusenko. Single-loop pneumatic systems for automatic regulation of thermal processes. Gosenergoizdat, 1963.
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Electronic intermittent-action controller of the REP-1M type. Technical description and instructions for installation, adjustment, and operation, 1959.