5
CSS 8-180
Operating instructions
Safety sensor
EN
4. Electrical connection
4.1 General information for electrical connection
The electrical connection may only be carried out by
authorised personnel in a de-energised condition.
The power supply for the safety sensors must provide protection
against permanent over-voltage. Under fault conditions, the voltage
must not exceed 60 V. supply units according to IEC 60204-1 is
recommended.
The safety outputs can be integrated into the safety circuit of the control
system. For applications of PL e / control category 4 to ISO 13849-1,
the safety outputs of the safety sensor or sensor of the chain must be
wired to a safety monitoring module of the same control category .
Requirements for the connected safety-monitoring module:
• Dual-channel safety input, suitable for p-type safety sensors with NO
function.
• Digital inputs to EN 61131-2, Table "Standard operating ranges for
digital inputs (current sinking)"
The safety-monitoring module must tolerate internal functional tests of
the sensors with cyclic switch-off of the sensor outputs for max. 1 ms.
The safety-monitoring module must not be equipped with a cross-wire
detection function. The safety-monitoring module does not need to have
a cross-wire short monitoring function, if necessary, the cross-wire short
monitoring function must be disabled.
Information for the selection of suitable safety-monitoring
modules can be found in the Schmersal catalogues or in the
online catalogue on the Internet: www.schmersal.net.
4.2 Series-wiring
A 200 m long sensor chain can be set up. Please note that voltage
losses could occur (due to cable length, cable section, voltage drop/
sensor)! For longer cable lengths, the section of the connecting cables
must be taken as large as possible.
Wiring examples for series-wiring, refer to appendix
4.3 Note on the total length of a safety sensor chain
The voltage drop of a long sensor chain must be taken into account
when planning the wiring.
Typical resistance of the different sensor connecting cables (20°C):
0.50 mm
2
: approx. 36 Ω / km
0.34 mm
2
: approx. 52 Ω / km
0.25 mm
2
: approx. 71 Ω / km
The resistance of the safety outputs / sensor used is load-dependent:
• 300 mΩ at 1 A current load, i.e. max. load of the safety outputs is
2 x 500 mA
• 30 mΩ at 100 mA current load, i.e. 2 x 50 mA load when a safety-
monitoring module is connected.
• Power consumption of a safety sensor approx. 30 mA
• Diagnostic output of a safety sensor max. 50 mA
Protection is not required when pilot wires are laid. The cables however
must be separated from the supply and energy cables. The max. fuse
rate for a sensor chain depends on the section of the connecting cable
of the sensor.
When wiring SD devices, please observe the voltage drop on
the cables and the current carrying capacity of the individual
components.
5. Set-up and maintenance
5.1 Functional testing
The safety function of the safety components must be tested. The
following conditions must be previously checked and met:
1. Fitting of the sensor and the actuator
2. Fitting and integrity of the power cable
3. The system is free of dirt and soiling (in particular metal chips)
5.2 Maintenance
In the case of correct installation and adequate use, the safety sensor
features maintenance-free functionality.
A regular visual inspection and functional test, including the following
steps, is recommended:
1. Check the fitting and integrity of the safety sensor, the actuator and
the cable
2. Remove possible metal chips
Measures must be taken to protect against manipulation or
against the bypassing of safety device, for example, using an
extra actuator.
Damaged or defective components must be replaced.
