详细介绍：
NPU 800 relay ensures the monitoring of the voltages of electrical supply networks whereas the NPUH 800 protects three-phase networks with isolated or high impedance earthed neutrals against earth-faults
ANSI FUNCTIONS FOR NPU 800 :
59 / 27 / 27 P / 81O / 81U / 86 / 74TC
ANSI FUNCTIONS FOR NPUH 800 :
59N / 86 / 74TC
