JPS55134318A - Level detector - Google Patents

Abstract

PURPOSE: To accurately, speedily and continuously detect the level of an object in a vessel by using a level detector having a temperature sensitive material, differentiators, first and second judgement-control unit, subtractors, operators, a smoothing circuit and a divider.

CONSTITUTION: Signals T₁WT₅ of thermo-electromotive force generated in thermocouples 1W5, respectively, are input into relative differentiators 9, and differentiation values thus obtained are input into the first judgement-control unit 10 to judge the values and determine a thermocouple section in which the level of an object is included. When no thermocouple section is determined by the unit 10, differences between the signals T₁WT₅ of thermo-electromotive force and a reference signal T₀ are calculated by subtractors 12 and then subjected to judgement in the second judgement-control unit 13. An operator 15 is adapted to calculate a reference value on the basis of a signal of a thermo-electromotive force from a thermocouple lower than a predetermined level. An output signal Ts' from the operator 15 input into a smoothing circuit 16, and an output Ts from the smoothing circuit 16 is sent to a divider 17. An operator 14 is adapted to determine a sum of signals T₁WT₅ and send a signal TM to the divider 17. In the divider 17, calculation in accordance with an equation TL=TM/TS is conducted, and TL is input into a phase advance compensation unit 18, in which the delay of signal is compensated to generate an output level signal.

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