Siemens temperature module relay pt100 1000 3rs1040 1gw50 3rs10 siemens 3rs1040 1gw50 p the siemens 3rs1040 1gw50 temperature monitor relay is used for monitoring the temperature of solid liquid and gaseous media the temperature is measured by a sensor in the medium converted by the unit and it is then checked if the temperature is too high too low or within a specified window depending on the settings the output relay will pick up or drop off when a threshold is exceeded primary ap