Option description and instructions
Contents this chapter
This chapter describes the +Q957 Prevention of unexpected start-up option and instructs how to wire,
start up, test, validate, use and maintain it. The safety data is also given.
+Q957 basic function description
The Prevention of unexpected start -up (POUS) function disables the drive output stage by utilizing the
STO function.
This prevents the drive from generating the torque required to rotate the motor. The POUS function
activates the Safe torque off (STO) function of the drive. By using this function, short-time operations
(like cleaning) and/or maintenance work on the non-electrical parts of the machinery can be performed
without switching off and disconnecting the drive.
The user activates the Prevention of unexpected start-up function using a switch mounted on a control
desk. When the switch is open (off), the POUS function is active and the POUS indication lamp is on.
The customer is responsible for installing and connecting the operating switch and the indication lamp
on site. They can be included in the delivery as an option. See the machine-specific C-type standards
whether the indication lamp is required.
For a detailed description of the Safe torque off function, see the appropriate hardware manual
The design principles of the Q957 comply with EN 1037.
The STO function complies with EN/IEC 61800-5-2:2007.
For a complete list of related standards and European directives, see section
Related standards and
directives
on page 18 .
Note
: Drives with the Emergency stop, stop category 1 function (Q952 or +Q964): If the user
activates the POUS function during the emergency stop deceleration ramp, it overrides the emergency
stop function. This activates the STO function of the drive immediately and the motor coasts to a stop.
For more information on the emergency stop function, see the appropriate user’s manual.
Basic timing diagram
Stop
STO
Inactive
Active
Speed
POUS
Drive Status
Standstill
