ABB ACS800 Hardware Manual page 8

4
WARNING! The Safe torque off function does not disconnect the voltage of the main
and auxiliary circuits from the drive. Therefore maintenance work on electrical parts
of the drive or the motor can only be carried out after isolating the drive system from
the main supply.
Note: The Safe torque off function can be used for stopping the drive in emergency
stop situations. In the normal operating mode, use the Stop command instead. If a
running drive is stopped by using the function, the drive will trip and stop by coasting.
If this is not acceptable, e.g. causes danger, the drive and machinery must be
stopped using the appropriate stopping mode before using this function.
Note concerning permanent magnet motor drives in case of a multiple IGBT
power semiconductor failure: In spite of the activation of the Safe torque off
function, the drive system can produce an alignment torque which maximally rotates
the motor shaft by 180/p degrees. p denotes the pole pair number.
Note: If you add or modify the wiring in the drive safety circuits, ensure that the
appropriate standards (e.g. IEC 61800-5-1, EN 62061, EN/ISO 13849-1 and -2) and
the ABB guidelines are met. After making the changes, verify the operation of the
safety function by testing it.
NEW (page 75): Installation of ASTO board (Safe torque off, +Q967)
What this chapter contains
This chapter describes
• electrical installation of the optional Safe torque off function (+Q967) of the drive.
• specifications of the board.
Safe torque off (+Q967)
The optional Safe torque off function includes an ASTO board, which is connected to
the drive and an external power supply. See also chapter Planning the electrical
installation, page 50.
Installation of the ASTO board
WARNING! Dangerous voltages can be present at the ASTO board even when the
24 V supply is switched off. Follow the Safety instructions on the first pages of this
manual and the instruction in this chapter when working on the ASTO board.
Make sure that the drive is disconnected from the mains (input power) and the
24 V source for the ASTO board is switched off during installation and
maintenance. If the drive is already connected to the mains, wait for 5 min after
disconnecting mains power.
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