  Motivated by the task to design quench protection systems for superconducting
magnets in particle accelerators we address a coupled field/circuit simulation
based on a magneto-quasistatic field modeling. We investigate how a waveform
relaxation of Gau{\ss}-Seidel type performs for a coupled simulation when
circuit solving packages are used that describe the circuit by the modified
nodal analysis. We present sufficient convergence criteria for the coupled
simulation of FEM discretised field models and circuit models formed by a
differential-algebraic equation (DAE) system of index 2. In particular, we
demonstrate by a simple benchmark system the drastic influence of the circuit
topology on the convergence behavior of the coupled simulation.
