NORD Drivesystems BU0530 - Manual (Page 27)

2 Description of function
BU 0530 GB-3712 27
2.3.4 Example without safe shut-down method
It is possible to implement the safety functions STO or SS1 with a digital input and a protective switching
device. With this switching version, as a maximum, Safety Category 1 as per DIN EN ISO 13849-1 can be
achieved, if in addition to the digital inputs, all other components (protective switching device, emergency stop
button, wiring) fulfil the requirements for Category 1.
This switching version should only be considered if only low requirements for functional safety need to be
fulfilled and if the risk assessment has shown that failure of the safety function can only result in slight (usually
temporary) injuries (see also Section 6 ). In case of doubt, the "Safe pulse block" should always be used.
Note: The optional filter is only required in environments with heavy interference.
To implement the safety function STO, the digital input is parameterised to the function "Disable voltage".
With the safety function SS1 the digital input is assigned the function "Fast stop" (parameter P420[-01...-04])
and the fast stop time is set via parameter P426. It must be ensured that the drive is brought to standstill within
the parameterised fast stop time.
NOTE
As a maximum, this example achieves Safety Category 1 or Performance Level c. This circuit
version is not SIL-capable
(See Section 6).
DIN1 ...
GND
DIN4
40
24
24V
Reset
24V
Frequency inverter
optional
Emergency stop button
Reset circuit
Safety output
Use of a
digital input
STO: P420[-01...-04]=10, "Disable voltage"
SS1: P420[-01...-04]=11, "Fast stop"
Filter
for
OSSD
Shielded cable to eliminate
errors as per
DIN EN ISO 13849-2
Supply voltage
Input circuit
with short-
circuit
detection