Surge arresters prophylaxis

State evaluation for metal-oxide surge arresters without gaps and classic surge arresters with spark gaps and silicon carbide

 

S.C. NOVA INDUSTRIAL S.A. evaluates the technical state of the surge arresters in service, on-line or off-line, based on appropriate measurements and tests done according to the national - international standards and the operation and maintenance recommendations / instructions given by the manufacturers.

 

The analysis of the tests results is done taking into account the evolution of the main parameters that individualize the state of the surge arresters,  S.C. NOVA INDUSTRIAL S.A. owning a large date base in this respect.

 

S.C. NOVA INDUSTRIAL S.A. owns also the appropriate high performance apparatus and equipment necessary to test the metal-oxide surge arresters without gaps and the classic surge arresters with spark gaps and silicon carbide.

 

The main types of diagnoses tests and measurements used are:

 

1. Technical state assessment for metal oxide surge arresters in service:

 

  • measurement of the resistive current through metal oxide surge arrester in service, by means of a monitor equipment based on  the harmonic analysis of the current that goes through the surge arrester  and  using the third harmonic with the compensation of the influence of the 3rd harmonic from the network’s voltage;
  • measurement of the r.m.s. and peak values of the leakage current through the surge arrester in service, under normal service voltage;
  • measurement of the third harmonic of the leakage current in service, under normal service voltage.

 

2. Technical state assessment of the surge arrester with spark gaps:

 

  • measurement of the leakage current through the surge arrester in service, under normal service voltage;
  • measurement of the leakage current with the voltage applied from a specialized installation;
  • measurement of sparkover voltage, at power frequency.

 

3. Operating test for surge counters related to surge arresters.