SYSTEM FOR MONITORING INSULATION OF LOW VOLTAGE NON-GROUNDED SYSTEM

摘要

PURPOSE: To obtain an inexpensive insulation-monitoring system for a low voltage system which can monitor a tendency. ;CONSTITUTION: A control resistor 11 is set at a tertiary open delta circuit 10c of a transformer 10 for a grounded meter, thereby to constitute a non- grounded system restricting a ground fault current. An apparent zero-phase voltage V0_x generated at the tertiary open delta circuit 10c is measured by a measuring/converting part 12. Meanwhile, a leak current, is measured by a zero-phase transformer 13 for each of low-voltage electric line parts 3. A static capacity Cf of three phases altogether to ground is measured beforehand. A simple vector operation using the above measured values, namely, minute zero-phase voltage V0_x, leak current 10 and static capacity Cf is conducted at an operating part 14. Accordingly, a resistor leak current Igr and an AC insulation resistance value Rg are derived.;COPYRIGHT: (C)1996,JPO