5.11 Safety Function5-795 Operation5.11 Safety FunctionThe safety function is incorporated in the SERVOPACK to reduce the risk associated with the machine by pro-tecting workers from injury and by securing safe machine operation. Especially when working in hazardousareas inside the safeguard, as for machine maintenance, it can be used to avoid adverse machine movement.5.11.1 Hard Wire Base Block (HWBB) FunctionThe Hard Wire Base Block function (hereinafter referred to as HWBB function) is a safety function designedto baseblock the motor (shut off the motor current) by using the hardwired circuits: Each circuit for two chan-nel input signals blocks the run signal to turn off the power module, and the motor current is shut off. (Refer tothe diagram below.)Note: For safety function signal connections, the input signal is the 0V common and the output signal is the source output.This is opposite to other signals described in this manual. To avoid confusion, the ON and OFF status of signals forsafety functions are defined as follows:ON: The state in which the relay contacts are closed or the transistor is ON and current flows into the signal line.OFF: The state in which the relay contacts are open or the transistor is OFF and no current flows into the signalline.(1) Risk AssessmentPerform risk assessment for the system and confirm that the safety requirements with the following standardsare fulfilled before using the HWBB function.EN954-1 Category3IEC61508-1 to 4 SIL2The following risks can be estimated even if the HWBB function is used. These risks must be included in therisk assessment.• The motor will rotate in an application where external force is applied to the motor (for example, gravity onthe vertical axis). Take measures to secure the motor, such as installing a mechanical brake.• The motor may move within the electric angle of 180 degrees in case of the power module failure, etc. Thenumber of rotations or movement distance depends on the motor type as shown below.Rotary motor: 1/6 rotation max. (rotation angle at the motor shaft)Direct-drive motor:1/20 rotation max. (rotation angle at the motor shaft)Linear motor: 30 mm max.• The HWBB function does not shut off the power to the servo drive or electrically isolates it. Take measuresto shut off the power to the servo drive when performing maintenance on it, etc./HWBB1+ 4365/HWBB1-/HWBB2+/HWBB2-0 VControl circuitRun signalSERVOPACKCN8SwitchBlockBlockPower modulePower supply24-V power supplyFuseMotor
