Functional Safety Interfaces - SIL ratings
The following table states the maximum ‘SIL capability’ that can be claimed for MTL4500 (backplane-mounted) and MTL5500 (DIN-rail mounted) intrinsic safety isolator modules, in accordance with IEC 61508: 2010 (Edition 2.0).
The table includes columns for Hardware Fault Tolerance (HFT), where HFT = 0 indicates the use of a module in a simplex, non-redundant arrangement, and HFT = 1 indicates the use of a module in a redundant arrangement. Simplex architectures may be referred to as 1oo1 (One out of One); whereas redundant architectures include 1oo2, 2oo3 etc. In redundant, voting architectures, the logic solver must resolve the status.
In the case of MTL intrinsic safety isolators, a redundant arrangement would typically consist of parallel ‘arms’ within the Safety Instrumented Function (SIF), where both the MTL isolator and its associated field instrument are duplicated or triplicated.
Note that the Safety Integrity Level (SIL) correctly applies to the entire safety function. However, a SIL ‘capability’, or SIL ‘attainment’ is often declared for individual elements, such as the MTL intrinsic safety modules. These indicate the highest SIL that is achievable for the overall safety function if the element is used within it. Note however that assembling multiple SILx capable elements does not ensure that the overall safety function will achieve SILx.
The SIL numbers given in the table relate to the IEC 61508: 2010 standard. For process applications, the sector-specific standard, IEC 61511, may require additional levels of hardware redundancy. In particular, Table 6 (“Minimum HFT requirements according to SIL”) of IEC 61511: 2016 (Edition 2.0) requires HFT = 1 for SIL 3 safety functions.
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Module type
|
Number of channels |
Function |
Suitable for use in Safety Functions up to, in accordance with IEC 61508:2010 (Ed. 2):
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|
MTL4500 |
MTL5500 range |
HFT = 0 |
HFT = 1 |
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|
Digital Input |
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|
MTL4501-SR |
MTL5501-SR |
1 |
Fail-safe solid state output + LFD |
SIL3 |
SIL3 |
|
MTL4504 |
1 |
Switch/prox input, phase reversal + LFD |
SIL2 |
SIL3 |
|
|
MTL4511 |
MTL5511 |
1 |
Switch/prox input, c/o relay output |
SIL2 |
SIL3 |
|
MTL4514/B/N/D |
MTL5514/D |
1 |
Switch/prox input, relay + LFD |
SIL2 |
SIL3 |
|
MTL4516 |
2 |
Switch/prox input, relay + LFD outputs |
SIL2 |
SIL3 |
|
|
MTL4516C |
MTL5516C |
2 |
Switch/prox input, c/o relay + LFD outputs |
SIL2 |
SIL3 |
|
MTL4517 |
MTL5517 |
2 |
Switch/prox input, relay + LFD outputs |
SIL2 |
SIL3 |
|
Digital Output |
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|
MTL4521 |
MTL5521 |
1 |
Loop-powered solenoid driver, IIC Gas Group |
SIL3 |
SIL3 |
|
MTL4521L |
1 |
Loop-powered solenoid driver IIC Gas Group, low power |
SIL3 |
SIL3 |
|
|
|
MTL5522 |
1 |
Loop-powered solenoid driver, IIB Gas Group |
SIL3 |
SIL3 |
|
MTL4523/V |
MTL5523/V |
1 |
Separately-powered solenoid driver with LFD |
SIL2 |
SIL3 |
|
MTL4523VL |
1 |
Separately-powered solenoid driver with LFD |
SIL2 |
SIL3 |
|
|
MTL4523L |
1 |
Loop- powered solenoid driver with LFD |
SIL3 |
SIL3 |
|
|
MTL4523R |
1 |
Separately-powered solenoid driver with reverse LFD |
SIL2 |
SIL3 |
|
|
MTL4523Y |
1 |
Separately-powered solenoid driven with voltage control |
SIL2 |
SIL3 |
|
|
MTL4524 |
MTL5524 |
1 |
Separately-powered solenoid driver, switch operated |
SIL2 |
SIL3 |
|
MTL4524S |
1 |
Separately-powered solenoid, 24V override |
SIL2 |
SIL3 |
|
|
MTL4525 |
MTL5525 |
1 |
Separately-powered solenoid driver, switch operated, low power |
SIL2 |
SIL3 |
|
Analogue Input |
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|
MTL4541 |
MTL5541 |
1 |
2/3 wire transmitter repeater, safe area current source |
SIL3 |
SIL3 |
|
MTL4541B |
1 |
2/3 wire transmitter repeater, safe area current source |
Refer AI module Safety Manual |
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|
MTL4541S |
MTL5541S |
1 |
2/3 wire transmitter repeater, safe area current sink |
SIL3 |
SIL3 |
|
MTL4544 |
MTL5544 |
2 |
2/3 wire transmitter repeater, safe area current source |
SIL3 |
SIL3 |
|
MTL4544B |
2 |
2/3 wire transmitter repeater, safe area current source |
Refer AI module Safety Manual |
||
|
MTL4544S |
MTL5544S |
2 |
2/3 wire transmitter repeater, safe area current sink |
SIL3 |
SIL3 |
|
MTL4544D |
MTL5544D |
1 |
2/3 wire transmitter repeater, dual output |
SIL3 |
SIL3 |
|
Analogue Output |
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|
MTL4546 |
MTL5546 |
1 |
4-20mA smart isolating driver + LFD |
SIL2 |
SIL3 |
|
MTL4546C |
1 |
4-20mA smart isolating driver + oc LFD |
SIL2 |
SIL3 |
|
|
MTL4546Y |
MTL5546Y |
1 |
4-20mA smart isolating driver + oc LFD |
SIL2 |
SIL3 |
|
MTL4549 |
MTL5549 |
2 |
4-20mA smart isolating driver + LFD |
SIL2 |
SIL3 |
|
MTL4549C |
2 |
4-20mA smart isolating driver + oc LFD |
SIL2 |
SIL3 |
|
|
MTL4549Y |
MTL5549Y |
2 |
4-20mA smart isolating driver + oc LFD |
SIL2 |
SIL3 |
|
Fire and Smoke |
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|
MTL4561 |
MTL5561 |
2 |
Loop-powered for fire and smoke detectors |
SIL2 Note 1 |
TBA |
|
Vibration |
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|
MTL4531 |
MTL5531 |
1 |
Vibration probe interface |
SIL1 |
SIL1 |
|
Temperature input |
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|
MTL4582B |
MTL5582B |
1 |
RTD isolator |
SIL 1 |
SIL 1 |
Notes
1. MTL Data Declaration only