Method of calibrating and/or monitoring a controlled-temperature heating device

摘要

A heated galette is provided with a heating unit and a temperature sensor connected in a control circuit with the heating unit to maintain a certain temperature of the surface of the galette on which a synthetic yarn is guided. The control circuit is disconnected periodically or intermittently so that the heating unit can be heated independently of the feedback control provided by the control unit. Upon the heating unit attaining an equilibrium with temperature, a first actual value temperature is measured and a difference is obtained from a setpoint temperature corresponding to a given control ratio and a signal representing the difference is generated. Utilizing this system, it is possible to detect failure of the temperature sensor and/or the heating unit or inappropriate positioning of the temperature sensor.