tokens: An upper value of common mode voltage shall be specified considering : 1 . power quality requirements defined in ECSS - E - ST-20 for “ Spacecraft bus ” , 2 . type of detectors and sensitivity , 3 . characteristics of analogue signal monitor receiver circuit , in accordance with ECSS - E - ST-50 - 14 , Table 5 - 2 d , 4 . characteristics of bi - level signal monitor receiver circuit , in accordance with ECSS - E - ST-50 - 14 , clause Table 6 - 2 e , 5 . hazards due to fault currents internal to the space vehicle or between the space vehicle and its electrical ground support equipment