5
vacon • 20 STO and SS1 safety functions
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5.3 Technical details
5.3.1 Response times
5.3.2 Connections
In addition to the STO inputs, the board contains also a thermistor input. If the thermistor input is
not used, it must be disabled. The thermistor input is disabled by making a short circuit to the ter-
minals and setting the jumper X23 in "OFF" state. The thermistor input operation and instructions
are presented in chapter 7.1.
* If 230VAC is used as control voltage from the output relays, the control circuitry must be powered
with a separate isolation transformer to limit short circuit current and overvoltage spikes. This is
to prevent the welding on the relay contacts.
Safety function
Activation
time
De-
activation
time
Safe Torque Off (STO) < 20 ms 500 ms
Table 1. STO response times
Terminal Technical information
1 STO1+ Isolated STO input 1, +24V +-20% 10... 15mA
2 STO1- Virtual GND 1
3 STO2+ Isolated STO input 2, +24V +-20% 10... 15mA
4 STO2- Virtual GND 2
25 RO1 Relay output 1 (NO) *
Switching capacity:
• 24VDC/8A
• 250VAC/8A
• 125VDC/0.4A
Min. switching load: 5V/10mA
26 RO2
28 TI1+
Thermistor input; R
trip
> 4.0 kΩ (PTC)
29 TI1-
Table 2. OPTBJ I/O terminals
V
STO1+
- V
STO1-
V
STO2+
- V
STO2-
STO state
0VDC 0VDC STO active
24VDC 0VDC STO diagnostic fault
0VDC 24VDC STO diagnostic fault
24VDC 24VDC STO inactive
Table 3. STO function truth table