Operating Behaviour Of The Monitoring Equipment; Time Dependencies - Pfannenberg PMF 2015-SIL Instructions De Service

4.5. Operating behaviour of the monitoring equipment

For the evaluation of the monitoring a superior control system, which is in accordance with the functional
safety requirements of IEC/EN61508, must be available. The control system must be capable of carrying out
a fault analysis according to the capacity of failure in connection with the operational condition of the flashing
light. The following dependencies between operational condition and capacity of failure are therefore possi-
ble. Please also take note of the possible switching status as shown in Fig. 9.
a) Switching on the power supply of the flashing light channel whilst there is simultaneous supply to the
monitoring circuit, in a fault-free condition, results in the switch of the relay contacts S1 and S2. If the
switch does not take place, then a fault has occurred in the diagnosis channel or the connection lines
(see also the time dependencies in Fig. 9). This also affects switching off the power supply of the
flashing light channel and the monitoring circuit.
b) Should, during the operating phase of the light, it become the case that the flashes stay off, then the
alarm relay is set off within 1.5 - 3.5 seconds.
c) Please note! When activating the monitoring equipment before the activation of the flashing light, the
alarm relay immediately activates and deactivates after a maximum of 3.5s. The diagnosis switch is
then in stand-by mode. If flashes are recognised then the alarm relay activates again after a maxi-
mum of 2.5s. If the flashing light channel is activated withing 1s has passed after switching on the
operational voltage of the diagnosis channel, then the alarm relay does not deactivate.
d) Broken cables or short circuits at the capacity of failure can be detected in addition because of the
forcibly guided relay contacts NC and NO by a superior control system.
e) If there are 'sticking' relay contacts and simultaneous further faults to the light in the operating phase,
then the fault of the light cannot be immediately recognised as the contacts do not switch in this
case. This fault can be recognised by switching off the power supply, as at this point a switch of the
fault alarm contacts is expected.

4.6. Time dependencies

In the following, time dependencies and possible switching status are shown:
Fig. 9 Function time diagram
Datei/ file name:085501931f D-E-F.doc
Fault, no flash
24 / 44 Zeichnungsnr./ Drwg-no.: 11516-42e