D6038
- SIL3 Line-Fault Transp. Switch/Prox. Repeater
G.M. International ISM0433-0
5
Testing procedure at T-proof
The proof test shall be performed to reveal dangerous faults which are undetected by diagnostic. This means that it is necessary to specify how dangerous undetected fault,
which have been noted during the FMEDA, can be detected during proof test.
Note for switch input: to detect a broken wire, or a short circuit condition, in the input connections it is necessary to mount, close to the switches, the end of line resistors:
R1=1 K
Ω
typical (470
Ω
to 2 K
Ω
range) resistor in series and R2=10 k
Ω
typical (5 K
Ω
to 15 K
Ω
range) resistor in parallel to the contacts.
The Proof test
consists of the following steps:
Steps
Action
1
Bypass the safety-related PLC or take other appropriate action to avoid a false trip.
2
For each channel, change the state conditions of the input sensors/contacts coming from field and verify, by ohmmeter connect to output terminals, that output
resistance change value from RL to RH or vice versa (according to direct or reverse function setting up by Dip-switches). RL and RH measured values must be
equivalent to RL and RH values within ±5% tolerance, defined on related product instruction manual .
3
For each channel, if input line fault detection is enable by Dip-switches specific set up, disconnect the input wiring coming from the field sensor/contact and check,
by ohmmeter connect to output terminals, that output resistance goes to RH value. Then, put in short condition the input connections and verify again that output
resistance goes to RH value. RH measured values must be equivalent to RH values within ±5% tolerance, defined on related product instruction manual.
In both case the related channel alarm LED, on the front panel, must be turned on with red light.
4
Restore the loop to full operation.
5
Remove the bypass from the safety-related PLC or restore normal operation.
This test will reveal approximately 99 % of possible Dangerous Undetected failures in the repeater.
