Abstract: A modular closing resistor assembly can be added in line with the interrupter assemblies of an extra high voltage circuit breaker and has a relatively short length. The resistor element consists of two stacks of disks which are disposed side by side and are electrically connected such that the alternate disks of each stack are connected in series with one another. The operating mechanism of the unit includes a linearly moving roller which engages a crank arm which is in turn pivotally connected to operate the movable closing resistor contact with a motion and with a variable mechanical advantage adapted to cause the resistor contacts to close at high speed just after the interrupter contacts close and to open after the interrupter contacts open.