Function Test (Low Demand Mode); Function Test (Starting Alarm); Process Safety Time; Proof Test And Lifetime - Pfannenberg PMF 2015-SIL Instructions De Service

4.7. Function test (low demand mode)

For the application in 'low demand mode' with safety requirements an automatic function test should be car-
ried out with regular intervals. The test intervals can be seen for evaluation in section 4.4.
Both part systems, the flashing light channel and the monitoring circuit, have separate power supply connec-
tions. This means that a check of the function is possible and can be carried out as follows (time dependen-
cies see also Fig. 9):
- Function test, if power supply is applied to the monitoring circuit permanently (Stand-by mode).
a) Check whether the fault alarm relay falls away when flashing light is switched off (no flash is generat-
ed)
b) Switching on the power supply of the flashing light, the fault alarm relay must have activated after a
maximum of 2.5s
c) 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
- 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 test that the switch of the relay contacts dependent on the flashing light generation is
detected. With which distances a test has to take place is dependent on the eventual use in which the flash-
ing 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. 9). 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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