D5095S - 5 A SIL 3 NC contact Relay Out Module for NE or F&G/ND Load G.M. International ISM0307-1
6
Configuration
For configuration of T-proof relays testing, some DIP Switches are located on component side of pcb. These switches allow the T-proof relays test (SW1 dip-switch: 1-2-3-4 set “ON” and
see “Testing procedure at T-proof” section for more information).
WARNING: after T-proof test, dip-switch 1-2-3-4 must be set
to “OFF” position for normal operation.
SW1 Dip switch configuration
1234
ON
T-proof relays enable
123
123
Normal Operation
ON ON
OFF
ON
OFFOFF
T-proof relays (dip1 = relay1;
dip2 = relay2; dip3 = relay3;
dip4 = relay4)
4
OFF
ON
4
This is factory settings
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 faults, which
have been noted during the FMEDA, can be revealed during proof test.
Before of Specific Proof Test, execute the following General Proof Test: connect the load supply lines to terminal blocks “7” (for +/AC) and “8” ( for -/AC) and the NE of F&G / ND load to
terminal blocks “11” (as the positive terminal) and “12” (as the negative terminal); finally, connect the DCS/PLC signal to input channel terminal blocks “1” (as the positive terminal) and
“2” (as the negative terminal). Then, verify the input to output functionality: the output NE load is normally energized by shutdown the input channel, while supplying of the input channel
de-energizes (safe state) the load; on the other hand, the output F&G / ND load is normally de-energized by energizing of the input channel, while shutdown of the input channel
energizes (safe state) the load. The channel functionality must be verified for a minimum to maximum input voltage change (from 21.6 to 27.6 Vdc) .
Then, disconnect the load supply lines from terminal blocks “7” - “8” and the output load from terminal blocks “11” - “12”. Then, connect an ohmmeter (Ohm. A) between terminal blocks
“7” - “11” and another one (Ohm. B) between terminal blocks “8” - “12”. In addition, the use of four relays for a single channel requires to control each relay coil by means of the internal
SW1 dip-switches (no. 1, 2, 3, 4) and to check the ohmic continuity of the contacts, as described in the following Specific Proof Test.
The Specific Proof Test consists of the following steps:
Testing procedure at T-proof
Steps Action
1Bypass the safety-related PLC or take any other appropriate action to avoid a false trip when removing the unit for test.
21. Do not supply the input channel (terminals “1” - “2”) of the unit under test and verify that ohmmeters Ohm. A and Ohm. B measure presence of ohmic
continuity (so that both +/AC and -/AC load lines are not interrupted because the NC contacts are closed: the 1st requisite is verified). For both ohmmeters,
Ohm. A or Ohm. B, these measures could also be true if only one of the two relay contacts in parallel is closed and the other one is blocked (for welding) in
the closed position (this can be verified by testing the channel when input is supplied, as described in point 2 of this procedure) or in the open position (this
can be verified by testing the channel when the input is supplied, as described in point 3 of this procedure). On the other hand, the absence of ohmic
continuity measured by ohmmeter Ohm. A or Ohm. B implies that two relay contacts are blocked (for welding) in the open position.
2. Supply the input channel (terminals “1” - “2”) of the unit under test and verify that ohmmeters Ohm. A and Ohm. B measure absence of ohmic continuity
(so that both +/AC and -/AC load lines are interrupted because all NC contacts are open: the 2nd requisite is verified). The presence of ohmic continuity
measured by ohmmeter Ohm. A or Ohm. B implies that at least one relay contact is blocked (for welding) in the closed position: this can be verified only by
disassembling and individually testing each relay.
3. Always supply the input channel (terminals “1” - “2”) of the unit under test in order to verify if a single relay contact is blocked (for welding) in the open
position. Considering the measure of ohmmeter Ohm. A, set ON the internal SW1 dip-switches (no. 1 or 2) to put in short circuit one relay coil at a time
(starting with the 1st coil by dip-switch no. 1, then going on with the 2nd coil by dip-switch no. 2), verifying that ohmic continuity is always present between
terminals “7” - “11”. Considering the measures of ohmmeter Ohm. B, set ON the internal SW1 dip-switches (no. 3 or 4) to put in short circuit one relay coil at
a time (starting with the 3rd coil by DIP-switch no. 3, then going on with the 4th coil by dip-switch no. 4), verifying that ohmic continuity is always present
between terminals “8” - “12”. In these situations, the absence of ohmic continuity implies that a relay contact (the one with the de-energized coil being
its dip-switch set ON, while the other one is energized) is blocked (for welding) in the open position.
3Remove the bypass from the safety-related PLC or restore normal operation inserting the unit.
This test reveals almost 99 % of all possible Dangerous Undetected failures in the relay module.
ON
