METHOD AND APPARATUS FOR TEMPERATURE CONTROL

摘要

The invention relates to a method to control the temperature for sealing devices used in the packaging industry which sealing devices are provided with electrically heated elements made of temperature dependent resistance material. The electrical current is divided in pulses whereby the length of the pulses is adjusted by means of a controlled switch (6). During the interruptions between the said current pulses, separate measuring current pulses of a constant and known value are generated which pulses will cause an electric voltage drop over the resistance element (2). Said voltage drop will be proportional to the temperature of the resistance element. The voltage drop will in a regulator (7) be compared with a set potential corresponding to a desired temperature whereby the sensed potential difference between the voltage drop measured and the set potential value is adapted to control a driving device (9) which will control the length of the heat generating current pulses.