LOW IMPEDANCE RESTRICTED DIFFERENTIAL EARTH FAULT ND10 LOW IMPEDANCE RESTRICTED DIFFERENTIAL EARTH FAULT

PROTECTIVE FUNCTIONS 50/51 Phase overcurrent 50N/51N - 87NHIZ. Residual overcurrent or high impedance restricted differential ground fault 64REF Biased restricted differential ground fault BF Breaker Failure

64REF – MOST COMMON APPLICATIONS Like every differential protective function 64REF is largely adopted in case of high selectivity needs. Common applications are generator protection and transformer protection. G ~ 64REF 64REF

BEFORE ND10 – 87NHIZ ONLY SEVERAL CONS Design Large cubicle NAXX STABILIZING RESISTOR SEVERAL CONS Design Large cubicle Connections Low liability External devices NAXX 3 CT’s Low leakage reactance type according to IEC Class PX, TPS or BS Class X 87N METROSIL 50 51 3 CT’s Phase Currents EXPENSIVE SOLUTION

ND10 – ONE DEVICE ONLY ND10 CHEAPER SOLUTION CT 3 CT’s Residual current ND10 50 51 3 CT’s Phase Currents CHEAPER SOLUTION

ND10 – 64 REF LOW IMPEDANCE FROM SAME INPUTS Separate inputs for phase current and current from earth connection. Earth overcurrent and biased restricted earth fault protective functions both contemporaneously performed. Phase overcurrent protective function from same 3 CT’s set. ND10 50N 51N 64 REF 50 51 RELIABLE SOLUTION

EASIEST SOLUTION in case of EARTH FAULT DIFFERENTIAL FUNCTION ND10 – MANY ADVANTAGES Biased 64REF is internally calculated. Easy connections. RS and METROSIL design is not required. No one external device is needed for stabilization. Smaller cubicles. ND10 50N 51N 64 REF 50 51 EASIEST SOLUTION in case of EARTH FAULT DIFFERENTIAL FUNCTION

External Market Support Oscar Ornago tel. +39.02.57495753 Piazza Federico Mistral, 7 20139 Milano (MI) ITALY Tel: +39.02.5749571 Fax: +39.02.57403763 e-mail: thytronic@thytronic.it company web site: www.thytronic.it products web site: www.pro-n.it External Market Support Oscar Ornago tel. +39.02.57495753 e-mail: o.ornago@thytronic.it