초록 ▼

A device for electric monitoring of the level of a liquid present in a container, with a temperature-dependent resistance probe which is immersed in the liquid the level of which is to be monitored, a source of constant current connectable, controlled by a timer, to the resistance probe, a circuit,

A device for electric monitoring of the level of a liquid present in a container, with a temperature-dependent resistance probe which is immersed in the liquid the level of which is to be monitored, a source of constant current connectable, controlled by a timer, to the resistance probe, a circuit, controlled by the timer, for detecting and storing an initial voltage drop on the resistance probe at an initial time and a measurement voltage at a defined time after the connection of the source of constant current, and a circuit for evaluating these voltages by subtraction of the measurement voltage from the initial voltage and if necessary under circumstances inversion of the difference in order to form a display voltage which corresponds to the level. There are provided a resistance probe structure for compensating for the influence of the change in level of the liquid on the display voltage due to thermal expansion as a function of its initial temperature and a computation circuit for compensating for different heat transfers from the resistance probe to the liquid as a function of the initial temperature.

대표청구항 ▼

In a device for electric monitoring of the level of a liquid present in a container, with a temperature-dependent resistance probe which is immersed in the liquid the level of which is to be monitored, a source of constant current connectable to the resistance probe, the current controlled by a time

In a device for electric monitoring of the level of a liquid present in a container, with a temperature-dependent resistance probe which is immersed in the liquid the level of which is to be monitored, a source of constant current connectable to the resistance probe, the current controlled by a timer, with means, controlled by the timer, for detecting and storing an initial voltage drop on the resistance probe at an initial time and a measurement voltage at a defined time after the connection of the source and constant current, and means for evaluating these voltages by subtraction of the measurement voltage from the initial voltage in order to form a display voltage which corresponds to the level, the improvement further comprising means for compensating for an influence of the change in level of the liquid, due to thermal expansion as a function of its initial temperature, on the display voltage, and means for compensating for different heat transfers from the resistance probe to the liquid as a function of the initial temperature.