Radio transmission modules having intrinsic safety

A method for achieving intrinsic safety of a radio transmission module with an HF power stage (RF-P) and an electronic control unit (Se) on a board for transmitting signals and measured values in an explosion-hazardous area, characterized by the following steps:

• monitoring HF output power at an antenna (A) by at least two independently operating hardware circuits (P1, P2, P3) by
• rectifying HF output voltage;
• comparing the rectified HF voltage with a maximum admissible value;
• acting on voltage supply of the radio transmission module to avoid an excessive ignition energy upon exceedance of the rectified HF voltage and/or
• potting an entire circuit board with a heat-conducting potting compound over components in a minimum layer thickness possible according to a standard;
• measuring a temperature in the potting layer by at least two independently operating hardware circuits (T1, T2, T3) distributed over the circuit board;
• comparing the measured temperature with an admissible limit value of the temperature inside the potting compound;
• and
• acting on the voltage supply of the radio transmission module to avoid an excessive power loss upon exceedance of the admissible limit value of the temperature.

An apparatus for transmitting signals in an explosion-hazardous area with intrinsic safety, comprising:

• a radio transmission module having a high frequency module and an electronic control circuit disposed on a printed circuit board, said electronic control circuit being configured to control a voltage supply to the high frequency module in response to one or more of:
• output voltage of the high frequency module exceeding a predetermined voltage value, as independently measured by at least two independently operating hardware circuits;
• and
• a temperature of a heat-conducting potting compound potted over heat generating components disposed on the printed circuit board exceeding a predetermined temperature value, as independently sensed by at least two independently operating temperature circuits.