Abstract: An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, a second measurement path including the battery, a negative-side insulation resistance, and the capacitor, a third measurement path including the battery, a positive-side insulation resistance, and the capacitor; and a control unit configured to calculate a reference value, based on each charging voltage of the capacitor in each measurement path, and configured to calculate an insulation resistance with reference to a predetermined conversion map, in which the conversion map includes a conversion map corresponding to a capacitance of the capacitor, and the control unit estimates the capacitance of the capacitor, and refers to the conversion map corresponding to the capacitance of the capacitor that has been estimated.

Abstract: A ground fault detection device includes: a detection capacitor; a switch group for switching between a first charging path connecting the battery and the detection capacitor, a second charging path connecting the battery, a negative side insulation resistance and the detection capacitor, a third charging path connecting the battery, a positive side insulation resistance and the detection capacitor, and a measurement path for measuring a charging voltage of the detection capacitor; and a controller configured to calculate the insulation resistance based on a charging voltage measured value of the detection capacitor which exists after charging each of the charging paths, wherein after measurement of the charging voltage of the second charging path, the controller is configured to cause the switch group to switch to the third charging path before switching to the first charging path.

Abstract: An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, and a second and third measurement paths including the battery, a positive/negative-side insulation resistance, and the capacitor; a reference resistance and a test switch; and a control unit calculating a first reference value based on each charging voltage in a case where the test switch is opened and the capacitor is charged, and calculating the insulation resistance with reference to a conversion map created to correspond to an electrostatic capacitance between a power supply line and ground, wherein the control unit calculates a second reference value based on each charging voltage in a case where the test switch is closed and the capacitor is charged for a shorter time, and estimates the electrostatic capacitance with reference to a predetermined test conversion map.

Abstract: An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, a second measurement path including the battery, a negative-side insulation resistance, and the capacitor, a third measurement path including the battery, a positive-side insulation resistance, and the capacitor; and a control unit configured to calculate a reference value, based on each charging voltage of the capacitor in each measurement path, and configured to calculate an insulation resistance with reference to a predetermined conversion map, in which the conversion map includes a conversion map corresponding to a capacitance of the capacitor, and the control unit estimates the capacitance of the capacitor, and refers to the conversion map corresponding to the capacitance of the capacitor that has been estimated.

Abstract: A ground fault detection device includes: a detection capacitor; a switch group for switching between a first charging path connecting the battery and the detection capacitor, a second charging path connecting the battery, a negative side insulation resistance and the detection capacitor, a third charging path connecting the battery, a positive side insulation resistance and the detection capacitor, and a measurement path for measuring a charging voltage of the detection capacitor; and a controller configured to calculate the insulation resistance based on a charging voltage measured value of the detection capacitor which exists after charging each of the charging paths, wherein after measurement of the charging voltage of the second charging path, the controller is configured to cause the switch group to switch to the third charging path before switching to the first charging path.

Abstract: An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, a second measurement path including the battery, a negative-side insulation resistance, and the capacitor, a third measurement path including the battery, a positive-side insulation resistance, and the capacitor; and a control unit configured to calculate a reference value, based on each charging voltage of the capacitor in each measurement path, and configured to calculate an insulation resistance with reference to a predetermined conversion map, in which the conversion map includes a conversion map corresponding to a capacitance of the capacitor, and the control unit estimates the capacitance of the capacitor, and refers to the conversion map corresponding to the capacitance of the capacitor that has been estimated.

Abstract: An earth fault detection apparatus includes a switch group configured to switch between a first measurement path including a battery and a capacitor, and a second and third measurement paths including the battery, a positive/negative-side insulation resistance, and the capacitor; a reference resistance and a test switch; and a control unit calculating a first reference value based on each charging voltage in a case where the test switch is opened and the capacitor is charged, and calculating the insulation resistance with reference to a conversion map created to correspond to an electrostatic capacitance between a power supply line and ground, wherein the control unit calculates a second reference value based on each charging voltage in a case where the test switch is closed and the capacitor is charged for a shorter time, and estimates the electrostatic capacitance with reference to a predetermined test conversion map.