Insulation fault detection device for testing for insulation faults under critical conditions

A device including a bridge assembly including: first, second, third, and fourth nodes, the first and third nodes being connected to a direct voltage source; a first branch connecting the first and second nodes; a second branch connecting the second and third nodes; a third branch connecting the first and fourth nodes; a fourth branch connecting the third and fourth nodes; a fifth branch connecting the second and fourth nodes and including a capacitor connected between the second and fourth nodes; a circuit controlling the switches to successively a) close the switches to charge the capacitor, and b) keep one switch closed and the other switches open; a measuring circuit measuring the current flowing through the capacitor; and a circuit determining magnitude of an insulation fault according to a current measured during b).