Residual time measurement in relay system - uses copy of thermal element on reduced time scale on model time delay circuit (SW 26.6.78)

摘要

A method is used for determining the residual time available from a relay in a thermal simulation system until its tripping. The thermal component of the element to be protected is copied, on a reduced time scale, on a model RC time-delay circuit. The time constant of the model is measured by a chronometer (3) which uses the same time scale. The measuring operations take place cyclically one after the other. The system includes a variable resistor (R2) connected to an amplifier system (2).