The Principle Of Sto; Technical Details - Vacon 20 X Installation, Technical And Maintenance Manual

Safe Torque Off
8.4

The principle of STO

The STO functionality, such as the technical principles and data (wiring examples and commission-
ing) will be described in this chapter.
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In VACON 20 X, the STO function is realized by preventing the propagation of the control signals to
the inverter circuit.
The inverter power stage is disabled through a galvanically isolated STO input (S1-G1). The operat-
ing conditions of the STO function are indicated in the following table:
STO inputs
Input energized with
Power removed from
8.4.1

Technical details

The STO input is a digital input intended for a nominal 24V d.c. input, positive logic (e.g. enabled
when high).
Absolute maximum voltage range
Typical input current at 24V
Response time at nominal voltage:
The reaction time of the STO function is the amount of time which passes from the moment in which
the STO is demanded until the system is in the Safe State. For VACON
ms maximum.
Make sure that the frequency converter is switched off before cabling.
When the STO function is used, the IP-class of the drive may not be reduced below
IP54. The IP-class of drive is IP65. It can be reduced by the wrong use of the cable
terminals .
Service support: find your nearest Vacon service center at www.vacon.com
Operating conditions
Normal operation
24V DC
STO demand
input
Table 82. Values of the torque on the motor.
Technical information:
Logic threshold
Reaction time
Table 83. Electrical data.
Torque at the
motor shaft
present (motor
on)
disabled (motor
de-energized)
Technical values
24V ±20%
10...15 mA
according to IEC 61131-2
15V....30V = "1"
0V....5V = "0"
<20ms
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20 X, the reaction time is 20
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