The lamps indicate “READY”, “MEASUREMENT IN PROGESS” AND “MEASUREMENT OVER” , using the relay outputs of the Model AUP-500. These indications are of great help to the operator, as they indicate whether the thermocouple is properly inserted into the lance before taking a reading and also whether the reading was completed without thermocouple burn out; in case the thermocouple becomes open before the sampling process is complete “Measurement Over” will not be indicated.