ISK 77 / SPK 77 - ASO Safety

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ISK 77 / SPK 77 Inductive Safety Relay
8.3 Connecting multiple sensors per sensor circuit (figure 1)
One or more sensors can be connected to sensor input O or C. For this purpose, the individual
sensors are connected in series according to figure 1.
Up to five sensors may be connected in series, whereby the total cable length must not exceed 25 m.
The length of one sensor ma�� be up to 25 m.
Before connecting the sensors that are connected in series, it is recommended that the resistance
value of the arrangement be measured.
The resistance must be 8.2 kW ± 100 W when the SCE is inactive and must not exceed 500 W when
it is active.
O
2
ASO sensors must not be connected in parallel.
Sensor 1
9. Electrical commissioning
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Sensor 2
C
Figure 1: Wiring of multiple sensors; in this example: safety contact edge
Sensor "n"
Connecting to the wrong terminals can destroy the switching unit.
9.1 Prerequisites
• When suppl��ing with 24 V AC/DC, the voltage must compl�� with the requirements for Safet�� Low
Voltage (SELV).
• All applied voltages must compl�� with the requirements for Safet�� Low Voltage (SELV). With
variant E, the outputs are not galvanicall�� separated from the suppl�� voltage.
• Cables installed outdoors or outside of the switching cabinet must be protected appropriatel��.
9.2 Electrical connection
• Connect 24 V suppl�� voltage to terminals B1 B2.
• Connect stationar�� sensors to the SCE OPEN and SCE CLOSE connections.
• Connect the safet�� circuit to be monitored to the appropriate connections for safet�� outputs Open
and Close. The cables are to be laid so that it is impossible to bridge the safet�� contacts, e.g. b��
a short circuit between the two connection wires (particularl�� with variant R).
Following successful commissioning, safet�� outputs are active. Actuation of a sensor causes the
respective safet�� output to switch to the inactive state.
Even while the safet�� outputs are being activated, their abilit�� to turn off is constantl�� tested (not with
variant R). For this purpose, the semiconductor output is switched off several times per second for
less than 1 ms and the response at the output monitored. If the voltage at the output does not switch
to the shut-down state, the device deactivates permanentl�� and can onl�� be reset b�� switching the
voltage suppl�� off and back on again. This permanent deactivation also occurs if, depending on the
t��pe of activation, the voltage cannot break down (e.g. b�� means of capacitive elements).
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