Sepam - HV/MV Protection and control units (ENG) - Trinet

Commissioning, settingsCheck:c the connections,c the positions of the microswitches SW associatedwith the current inputs,c the general parameters in the status menu.Set the following:c type of time delay:v definite time,v IDMT;c Is set point:Is is set as a percent of the basis current Ib.The 999% setting may be used to inhibitthe protection: all the outputs are set to 0.c T time delay:v definite time: T is the operation time delay,v IDMT: T is the operation time delay at 5Ib.The negative sequence unbalance time delay settingmust be greater than the earth fault protection settingso as to avoid unwanted tripping before the earth faultprotection in the presence of earth fault current.Typical settingsc Generator:v definite time,v Is = 0.15 Ib.c Motor controlled by contactor / fuse:v IDMT,v 0.3Ib < Is < 0.4 Ib,v T > 5 s.How does the user find out the tripping timefor different negative sequence current valuesfor a given curve?Using the chart, the user finds the value of K thatcorresponds to the desired negative sequencecurrent. The tripping time is equal to KT.ExampleGiven a tripping curve with the setting T = 0.5sWhat will the tripping time be at 0.6Ib?Using the chart, find the value of K that correspondsto 60% of Ib. It isK = 7.55. The tripping time is: 0.5 x 7.55 = 3.755 sIi (% Ib)K10 99.9515 54.5020 35.4425 25.3830 19.3233.33 16.5135 15.3440 12.5645 10.5350 9.0055 8.2157.7 7.8460 7.5565 7.0070 6.5275 6.1180 5.7485 5.4290 5.1395 4.87100 4.64110 4.24120 3.90130 3.61140 3.37150 3.15160 2.96170 2.80180 2.65190 2.52200 2.40Ii (% Ib)K210 2.29220 2.14230 2.10240 2.01250 1.94260 1.86270 1.80280 1.74290 1.68300 1.627310 1.577320 1.53330 1.485340 1.444350 1.404360 1.367370 1.332380 1.298390 1.267400 1.236410 1.18420 1.167430 1.154440 1.13450 1.105460 1.082470 1.06480 1.04490 1.02u 500 1* function available as of version 9802 SFT2800.Protection functions2/33