... , TN and IT power supply systems of AC 50Hz and 380V. 3. 35mm DIN rail Chtent 3P Series Surge Protective Device (10KA ... ,20KA,30KA,40KA,60KA,80KA,100KA......) Application: suitable for TT,TN and IT power supply systems ... .Surge Arrester TEN1-C/3P SPD is suitable for power supply networks of TN, TT and IT systems with modular design ...