Easy Start Guide
14. STO (Safe Torque Off) Connections
Page 14
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Bosch Rexroth EFC 5610 Series Inverter
Safe Torque Off (STO) is an optional safety feature
included with some EFC5610 Inverters. If present,
the Inverter will include a yellow STO connector. No
parameter changes are required to enable this
feature.
STO provides a facility to disable the output of the
Inverter so that the motor it is controlling cannot be
operated ie. that no torque can be applied.
However, it does not provide any form of braking so
will not prevent the load from rotating the motor.
This section is an overview only.
You must also refer to the manual
provided by the manufacturer for
full details of STO functionality.
The STO function is only effective when wired to
suitable safety devices that detect an 'unsafe'
situation. A safety assessment of the machinery
is required by suitably qualified personnel to
identify what should be considered ‘unsafe’ and
what safety devices are appropriate for the
application.
It is not recommend to stop a motor using the
Inverter STO function. The motor should be
stopped before STO is activated or an
error
message will be displayed.
Sto-r
STO does not isolate the electrical supply.
Therefore, the Inverter must be isolated from the
supply before any maintenance is carried out.
There are 12 terminals on the STO plug which
are bridged for easy connection. Therefore,
either the top 6 or bottom 6 can be used.
The Inverter is supplied with links configured
so that the Inverter can be used with STO
disabled. The illustration on the right shows
this arrangement. The links simply connect
STO channels 1 and 2 to 24V and common.
When the Inverter is powered up, 24V must be
present on both STO channels or an
alarm will be displayed and the motor will not
operate.
Sto-A
If 24V is lost on one channel an
error
message will be displayed.
Sto-E
When enabled, the STO channels are
connected to the external safety devices. The
manufacturer recommends that a suitable
external 24V power supply is used instead of
the +24V and COM terminals on the Inverter.
14.2 STO Enabled
If STO is to be used, remove all links.
14.1 STO Links (STO disabled, as supplied)
+24V
STO2+
STO1+
COM
STO1-
STO2-
+
STO1 (external channel 1)
STO2 (external channel 2)
+
-
-
This display will flash StO-A and the motor will not
start if 24V is not present on both STO channels
STO Disabled
STO Enabled
