
PNOZ 8
Operating Manual PNOZ 8
22152-EN-03 9
Function Description
The safety relay PNOZ 8 provides a safety-oriented interruption of a safety circuit. When
supply voltage is supplied the "POWER" LED is lit. The unit is ready for operation when the
feedback loop Y1-Y2 and the start circuit S12-Y1 are closed.
}Input circuit is closed (e.g. E-STOP pushbutton not operated):
– Safety contacts 13-14, 23-24 and 33-34 are closed, auxiliary contact 41-42 is open.
The unit is active.
– The LEDs "CH.1" and "CH.2" are lit.
– A high signal is present at the semiconductor output switch state Y32.
}Input circuit is opened (e.g. E-STOP pushbutton operated):
– Safety contacts 13-14, 23-24 and 33-34 are opened redundantly, auxiliary contact
41-42 is closed.
– The LEDs "CH.1" and "CH.2" go out.
– A low signal is present at the semiconductor output switch state Y32.
Semiconductor output fault Y35
}A low signal is present at semiconductor output Y35 if the supply voltage is present and
the internal fuse (circuit breaker) has not blown. If there is a fault on the safety relay, a
high signal is present at Y35, the "FAULT" LED lights. Once the cause of the fault has
been removed, the fuse must be reset via the reset pushbutton.
Operating modes
}Single-channel operation: No redundancy in the input circuit, earth faults in the start
and input circuit are detected.
}Dual-channel operation with detection of shorts across contacts: Redundant input cir-
cuit, PNOZ 8 detects
– earth faults in the start and input circuit,
– short circuits in the input circuit,
– shorts across contacts in the input circuit.
}Dual-channel operation without detection of shorts across contacts: Redundant input
circuit, detects PNOZ 8
– earth faults in the start and input circuit,
– short circuits in the input circuit.
}Automatic start: Unit is active once the input circuit has been closed.
}Manual start: Unit is active once the input circuit and the start circuit are closed.
}Monitored start: Unit is active once
– the input circuit is closed and then the start circuit is closed and opened again.
– the start circuit is closed and then opened again once the input circuit is closed.
}Increase in the number of available contacts by connecting contact expander modules
or external contactors/relays.