Optimum setting and coordination of overcurrent relays considering cable damage curve

Application of let‐through energy to back‐up over‐current protection on high‐voltage feeders

“…The conductor damage curve (annealing) is an I 2 t curve [8,11,17]. The maximum current that some conductor types can sustain for 1 s (without getting damaged) is shown in Table 1 [18].…”

“…Generally, current-based protection consists of an instantaneous element and a time-delayed element [10]. When setting the time-delayed over-current elements, the sensitivity of the pickup, the speed of operation and selectivity of the element are considered [11]. The relay operating time should be kept to a minimum [11].…”

“…When setting the time-delayed over-current elements, the sensitivity of the pickup, the speed of operation and selectivity of the element are considered [11]. The relay operating time should be kept to a minimum [11]. However, the time-delayed element is set slower than the main protection elements [3,5].…”

“…With main protection applied to HV feeders, little attention is given to ensure that the backup protection is actually protecting the feeder. A focus is placed on setting the protection insensitive to load current and sensitive to fault current [3][4][5][8][9][10][11][12]. This does not mean that the actual conductor is protected.…”

Analysis of Characteristics Over Current Relay and Ground Fault Relay on Feeder Rayon Tabing

“…In the access operation can not be used for error conditions (errors). One of the main tools in the protection system used is the current relay (overcurrent relay) [1] and soil relocation (Ground Faul Relay) [2,3]. This relay instructs the breaker (CB) to disconnect if a short circuit occurs.…”