Getriebebau NORD GmbH & Co. KG
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Technical Information / Datasheet STO/SS1
NORDAC PRO (SK 500P) TI 80_0030 V 1.0 3219 en
Functional Safety
To prevent danger to people and material it is necessary to be able to safely switch off machines. For
this, the frequency inverter provides the safety functions STO and SS1-t.
Safely torque switch-off: STO (Safe Torque Off)
With the STO function the drive torque is switched off as quickly as possible and the drive runs down
to a standstill. This behaviour corresponds to stop category 0 according to EN 60204-1. An undefined
time elapses before the drive unit does not carry out any further movement and a safe state is
achieved.
Safe Stop 1 with time control SS1-t (Safe Stop 1 time-controlled)
With the function SS1-t the motor is initially braked by the frequency inverter. After shut-down the STO
input must be externally switched to the STO function. This behaviour corresponds to stop category 1
(controlled braking) according to EN 60204-1.
Information
The safety functions STO/SS1-t are NOT certified and qualified, i.e. they have no warranted safety
characteristics and must only be used for test purposes. It is at the discretion of the user to ensure
adequate safety in the installations.
1 Validity of document
The following information applies for NORDAC PRO (SK 500P) series frequency inverters. The basic
and further information about the frequency inverters can be found in the following documents:
• BU 0530
, Issue 1217 (Part. No.: 6075301): Functional safety, supplementary instructions for
SK 500E series
• BU 0600, Issue 2319 (Part. No.: 6076001): NORDAC PRO (SK 500P)
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