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- Function test – carried out when switching on the power supply of the monitoring circuit
a) Before switching on the monitoring circuit, check whether the fault alarm relay has fallen away
b) Switching on the power supply of the flashing monitor with flashing light not switched on, the fault
alarm relay activates for max. 3,5s.
c) Check whether the fault alarm relay falls away correctly thereafter
d) Switching on the flashing light channel, the fault alarm relay must have activated after a maximum of
2.5s
e) Switching off the operational voltage of the flashing light channel, the fault alarm relay must have fall-
en away (high-resistance) after 3.5s at the latest
f)
Switching off the flashing monitor
It is important for the system test that the switch of the relay contacts dependent on the flashing light genera-
tion is detected. With which distances a system test has to take place is dependent on the eventual use in
which the flashing light is involved. The equipment specific check intervals must be defined in the respective
proof of safety.
4.8. Function test (starting alarm)
The algorithm, as described in section 4.7, must be carried out immediately before every time the machine is
switched on.
Note: in doing so the functionality of the monitoring channel (diagnosis channel) is tested according to the
IEC61508 required frequency.
4.9. Process safety time
Conclusions for the required process safety time can be drawn depending on use according to the function
time diagram (Fig. 10). The reaction times for the generation of the optical warning signal and the switching
status of the alarm relay depending on the switching on time of the operational voltage and in the case of a
fault (despite demand, the warning signal is not generated) are illustrated here.
After activating the operating voltage, the flashing light generates the first flash after approx. 1 to 1.5s. This
means the 'generation of a warning signal' safety function has been activated.
Further explanations of the reaction times of the alarm relay can be found in section 4.5.
4.10.
Proof test and lifetime
Checks of the electrical function, the visual condition and the determining of the operating hours of the warn-
ing lights are to be carried out at regular intervals. Proof tests serve to identify non-automatically diagnosa-
ble, dangerous faults and the procedure of the lifetime of flashtubes and flash capacitors.
If the proof test is not carried out in the required, defined, timely intervals this leads to the loss of the reacha-
ble SIL evaluation.
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