during this time by continuing the operation by the charged power of the capacitor in the servo amplifier 52 the effect on the robot operation can be almost completely ignored this fault check can be performed by a command from the processor 51 so can be performed while avoiding times of operations where the power consumption is large and suspension of the supply of power would be liable to have a detrimental effect as examples the fault check can be performed in a state braking the shafts of the robot and stopping the supply of torque to the servo motors can be performed in a state while the robot is idle between one job and another etc fig8 is a time chart showing a second fault check method of a servo power connection cutoff circuit after turning on the servo power in the examples above the precharging relay ka 1 and the electromagnetic contactor km 1 were simultaneously checked for faults but it is also possible to separate the timings for fault checks of the precharging relay ka 1 and electromagnetic contactor km 1 and thereby enable fault checks without completely stopping the supply of power to the servo amplifier 52 this example will be explained below with reference to fig8 after turning on the servo power the precharging relay ka 1 and electromagnetic contactor km 1 are both in the on state in this state the processor 51 issues an off command to the first precharging relay ka 1 timing of timing of t 5 at this time if the precharging relay ka 1 is free.