50
Options
CG Drives & Automation, 01-6142-01r0
These two signals need to be combined and used to enable
the output of the AC drive and make it possible to activate a
Safe Stop condition.
When the "Safe Stop" condition is achieved by using these
two different methods, which are independently controlled,
this safety circuit ensures that the motor will not start
running because:
•
The 24VDC signal is disconnected from the "Inhibit"
input, terminals 1 and 2, the safety relay K1 is switched
off.
The supply voltage to the driver circuits of the power
conductors is switched off. This will inhibit the trigger
pulses to the power conductors.
•
The trigger pulses from the control board are shut down.
The Enable signal is monitored by the controller circuit
which will forward the information to the PWM part on
the Control board.
To make sure that the safety relay K1 has been switched off,
this should be guarded externally to ensure that this relay did
not refuse to act. The Safe Stop option board offers a
feedback signal for this via a second forced switched safety
relay K2 which is switched on when a detection circuit has
confirmed that the supply voltage to the driver circuits is
shut down. See Table 34 for the contacts connections.
To monitor the "Enable" function, the selection "RUN" on
a digital output can be used. For setting a digital output, e.g.
terminal 20 in the example Fig. 107, please refer to section
10.5.4, page 138 [540].
When the "Inhibit" input is de-activated, the AC drive
display will show a flashing "SST" indication in section D
(bottom left corner) and the red Trip LED on the Control
panel will be flashing.
To resume normal operation, the following steps have to be
taken:
•
Release "Inhibit" input; 24V
DC
(High) to terminal 1
and 2.
•
Give a STOP signal to the AC drive, according to the set
Run/Stop Control in menu [215].
•
Give a new Run command, according to the set Run/
Stop Control in menu [215].
Fig. 54 Connection of safe stop option in size B .
Fig. 55 Connection of safe stop option in size E and up.
NOTE: The "Safe Stop" condition according to EN-IEC
62061:2005 SIL 3 & EN-ISO 13849-1:2006, can only be
realized by de-activating both the "Inhibit" and "Enable"
inputs.
NOTE: The method of generating a STOP command is
dependent on the selections made in Start Signal Level/
Edge [21A] and the use of a separate Stop input via
digital input.
WARNING!
The safe stop function can never be used for
electrical maintenance. For electrical
maintenance the AC drive should always be
disconnected from the supply voltage.
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