The requirements for switching high DC currents with inductive loads are VERY severe. I have worked on large industrial DC motor drives, where the output may be 0-500V and hundreds of amperes, into a motor winding. In the event of an emergency stop or other fault condition, where the output contactor gets dropped out under load, special construction is needed to dissipate the resulting arc energy. Large DC contactors often incorporate magnets near the separating contacts to help "stretch" and break up the arc before it vaporizes too much of the contact surfaces. Some systems use contacts sealed inside vacuum chambers, to prevent the formation of an arc through ionized air.