| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a non-grounded circuit which has an inverter for switching a positive terminal and a negative terminal of a DC power supply through a switching element and carrying a current to an electrical load, and an apparatus for detecting an insulation in the non-grounded circuit which improves the detection accuracy of an insulation level between ground potential sections. <P>SOLUTION: The apparatus includes: a charge/discharge setting circuit 60 connected between a connection point P1 of first and third resistors 21, 23 and a capacitor 53, and setting a charge current from the connection point P1 to the capacitor 53 to be higher than a discharge current from the capacitor 53 to the connection point P1; and an insulation level detecting means 71 for detecting a ground fault of the non-grounded circuit 10 based on a voltage V<SB>c</SB>across terminals of the capacitor 53 when positive wiring of the DC power supply 12 is switched to a positive terminal conduction state so as to be connected to a motor 40 and negative wiring of the DC power supply 12 is switched to a negative terminal conduction state so as to be connected to the motor 40 by switching element Q<SB>11</SB>, Q<SB>12</SB>, Q<SB>21</SB>, Q<SB>22</SB>, Q<SB>31</SB>, Q<SB>32</SB>in the inverter 10. <P>COPYRIGHT: (C)2010,JPO&INPIT |
