Abstract: An apparatus measures a voltage of a cell while scanning a group of cells in a cell stack, in which a plurality of cells is electrically connected in series. The apparatus has a first switching device and a voltage detecting device. The first switching device is connected in series with a signal line carrying a voltage of a cell. The voltage detecting device detects the voltage of the cell, which is electrically connected with signal lines carrying voltages of cells belonging to a group. When the first switching device is electrically connected with a connecting point between two successive groups of cells, the first switching device is shared by the two groups.

Abstract: A voltage measurement device includes a first group of switches Q1, Q2, a second group of switches Q7, Q8 and a third groups of switches Q5, Q6. By turning on the third group of switches Q5, Q6, the first group of switches Q1, Q2 are turned on, so that a condenser C1 is charged by voltage impressed between a voltage input terminal A and a voltage input terminal B. While the first group of switches Q1, Q2 are turned off by tuning off the third group of switches Q5, Q6, the second group of switches Q7, Q8 are turned on, so that voltage retained in the condenser C1 is generated between a voltage output terminal G and a voltage output terminal H.

Abstract: A voltage measurement device includes a first group of switches Q1, Q2, a second group of switches Q7, Q8 and a third groups of switches Q5, Q6. By turning on the third group of switches Q5, Q6, the first group of switches Q1, Q2 are turned on, so that a condenser C1 is charged by voltage impressed between a voltage input terminal A and a voltage input terminal B. While the first group of switches Q1, Q2 are turned off by tuning off the third group of switches Q5, Q6, the second group of switches Q7, Q8 are turned on, so that voltage retained in the condenser C1 is generated between a voltage output terminal G and a voltage output terminal H.

Abstract: An apparatus measures a voltage of a cell while scanning a group of cells in a cell stack, in which a plurality of cells is electrically connected in series. The apparatus has a first switching device and a voltage detecting device. The first switching device is connected in series with a signal line carrying a voltage of a cell. The voltage detecting device detects the voltage of the cell, which is electrically connected with signal lines carrying voltages of cells belonging to a group. When the first switching device is electrically connected with a connecting point between two successive groups of cells, the first switching device is shared by the two groups.

Abstract: A control section sets a positive side switching element of a positive side detection section and a negative side switching element of a negative side detection section to ON, thus outputting an ON signal. When the switching elements are set ON, a predetermined current outputted from a positive side constant current source and a negative side constant current source, or a portion of this current, flows through detection resistors. A ground fault decision section decides whether a ground fault has occurred in the positive or the negative side of a direct current power source, based upon the value of an output voltage detected by a positive side voltage detector, or upon the value of an output voltage detected by a negative side voltage detector. Ground faults are accurately detected with a simple structure.

Abstract: A control section sets a positive side switching element of a positive side detection section and a negative side switching element of a negative side detection section to ON, thus outputting an ON signal. When the switching elements are set ON, a predetermined current outputted from a positive side constant current source and a negative side constant current source, or a portion of this current, flows through detection resistors. A ground fault decision section decides whether a ground fault has occurred in the positive or the negative side of a direct current power source, based upon the value of an output voltage detected by a positive side voltage detector, or upon the value of an output voltage detected by a negative side voltage detector. Ground faults are accurately detected with a simple structure.