| 摘要 |
An electric heating system (1) is disclosed for the heating of the interior of an instrument cabinet and the like which is protected against explosion. The heating system includes a radiator (2) with a receiving cavity (3). A heating element (5) and a melting fuse (6) are connected in series as an excess-temperature fuse, whereby the heating element (5) and the excess temperature fuse (6) are disposed in receiving cavity where they are encapsulated. The heating element (5) and the excess-temperature fuse (6) are connected via connection lines (8, 14) to a temperature control (9). An environmental-temperature sensor (10) is also connected to the temperature control. According to the invention, a fuse-temperature sensor (11) is also encapsulated in the receiving cavity near the melting fuse which is connected to the temperature control (9). The current fuse temperature of the excess-temperature fuse (6) is determined by the fuse-temperature sensor (11) for comparison to a set changeover temperature. The changeover temperature is set at a temperature safely below the triggering temperature of the excess-temperature fuse (6). The temperature control (9) operates in a first control algorithm within a fuse temperature range below the preset changeover temperature. The temperature control (9) switches over to a second control algorithm when the changeover temperature has been reached or exceeded and lowers the heating performance of the heating element (5) for the protection of the excess-temperature fuse (6).
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