Patent ID: 8624611

Claim:
A measurement arrangement for monitoring galvanic isolation of a fuel cell device having at least one stack of fuel cells, at least one load circuit for fuel cells, and at least one ground potential structure connected to protective grounding near the at least one said stack, wherein the measurement arrangement comprises: at least one measurement element having known impedance for connection to at least one ground potential structure of at least one stack of fuel cells; means for performing measurements from the measurement element to form voltage information of floatage conditions of fuel cells towards said ground potential structure; at least two switches for switching at least two switching points of the fuel cells to said measurement element; and means for monitoring galvanic isolation including at least one signal processor for controlling said switches during measurements, and for processing said formed voltage information and at least voltage information between the switching points to form resistance information and capacitance information of galvanic isolation, wherein the capacitance information is based on a comparability between capacitance values and an exponential constant of a voltage information curve, and said at least one signal processor is provided for combining said resistance and capacitance information to form information on a condition of the galvanic isolation and information on possible alteration of said condition.