Emax Low voltage air circuit-breakers - ABB Download Center

Protection trip units and trip curvesPR122/POperation, protection functions and self-testBasic Protection functionsThe PR122 trip unit offers thefollowing protection functions(according to the version):• overload (L)• selective short-circuit (S)• instantaneous short-circuit (I)• earth fault (G) (2)• phase unbalance (U)• self-protection against overtemperature(OT)• thermal memory for functionsL and S• zone selectivity for functionsS and G• residual current (Rc) withexternal toroid• source ground return withexternal toroidSetting the neutralIn PR122/P, and PR123/P aswell, the neutral protection is50% of the value set for phaseprotection in the standard version.The neutral protectioncan be excluded or set to100% for E1, E2, E3, E4/f andE6/f. In installations where veryhigh harmonics occur, the resultingcurrent at the neutralcan be higher than that of thephases. Therefore it is possibleto set the neutral protection at150% or 200% of the value setfor the phases. In this case itis necessary to reduce the settingof protection L accordingly(1) .The table below lists the neutralsettings for the various possiblecombinations betweentype of circuit-breaker and thethreshold I1 setting.avoids untimely trippingcaused by the high inrush currentsof certain loads (motors,transformers, lamps).The start-up phase lasts from 100ms to 1.5 s, in steps of 0.05 s. Itis automatically recognized bythe PR122 trip unit as follows:– when the circuit-breakercloses with the trip unit selfsupplied;– when the peak value of themaximum current exceeds0.1 x In. A new start-up becomespossible after thecurrent has fallen below thethreshold of 0.1 x In, if thetrip unit is supplied from anexternal source.4Start-up functionThe start-up function allowsprotections S, I and G to operatewith higher trip thresholdsduring the start-up phase. ThisAdjustable neutral protection settingsThreshold I1 settings (overload protection)Circuit-breaker model 0.4 ≤ I1 ≤ 0.5 0.5 < I1 ≤ 0.66 0.66 < I1 ≤ 1(*)E1B-N 0-50-100-150-200% 0-50-100-150% 0-50-100%E2B-N-S-L 0-50-100-150-200% 0-50-100-150% 0-50-100%E3N-S-H-V-L 0-50-100-150-200% 0-50-100-150% 0-50-100%E4S-H-V 0-50-100% 0-50% 0-50%E4S/f-H/f 0-50-100-150-200% 0-50-100-150% 0-50-100%E6H-V 0-50-100% 0-50% 0-50%E6H/f 50-100-150-200% 0-50-100-150% 0-50-100%(*) The setting I1 =1 indicates the maximum overload protection setting. The actual maximum setting allowable must take into account anyderating based on temperature, the terminals used and the altitude (see the “Installations” chapter)(1) When three-pole circuit-breakers with external neutral current sensor are used, a setting above 100% for the neutral does not require anyreduction in the L setting up to Iu N.(2) The current values above which G is disabled are indicated in the installation manual.4/10ABB SACE