Diminishing the Conducted Emissions at a Monitoring and Diagnosis Equipment

The paper is concerned with an equipment used to monitor power transformers. The equipment is working in an environment where electromagnetic interference may occur, being able to transmit data related to the transformers operation. The monitoring equipment was submitted to tests for conducted emissions. The initial tests revealed that the compliance with the norms from the standard related to conducted emissions for this type of equipment was not achieved. Several measures had to be taken to pass the tests. The first step was to reduce the conducted emissions associated to the inputs in the supplying source. Therefore a ferrite filter was designed and implemented, being placed at the equipment general supplying input. The conducted emissions were again evaluated and again the tests were failed. Consequently a network filter had to be designed and placed. Finally the compliance with the norms relative to conducted emissions was obtained.