ABB RELION REX640 Technical Manual page 624

Protection and control

Hide thumbs Also See for RELION REX640:

Table of Contents

Protection functions

Figure 354: Operation timer characteristic of IFPTOC function when Operation

principle = "Touch voltage based", Operating curve type = "Inverse time IEEE80" and

IEEE multiplier = 500. Characteristics are according to standard IEEE80. Maximum

earthing Ris = 10ohm.

Cross-country fault protection

In high impedance earthed networks, single phase earth fault introduces over-

voltages in the healthy phases. Such over-voltages may initiate another single-phase

earth fault in another phase and location in a galvanically connected network. Such

fault condition is commonly known as cross-country fault, which is a two phase

short-circuit through earth with high earth fault current. Cross-country fault must

be therefore quickly disconnected in order to limit risk to health and damages to

1MRS759142 F

Technical Manual