Eaton MTL

MTL Instruments Group

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.

Module type

Number of channels

Function

Suitable for use in Safety Functions up to, in accordance with IEC 61508:2010 (Ed. 2):

MTL4500
range

MTL5500 range

HFT = 0

HFT = 1

Digital Input

 

MTL4501-SR

MTL5501-SR

1

Fail-safe solid state output + LFD

SIL 3

SIL 3

MTL4504

1

Switch/prox input, phase reversal + LFD

SIL2

SIL 3

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

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

MTL4522

 

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

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

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

MTL4546

MTL5546

1

4-20mA smart isolating driver + LFD

SIL2

SIL2 Note 1

MTL4546C

1

4-20mA smart isolating driver + oc LFD

SIL2

SIL2 Note 1

MTL4546Y

MTL5546Y

1

4-20mA smart isolating driver + oc LFD

SIL2

SIL2 Note 1

MTL4549

MTL5549

2

4-20mA smart isolating driver + LFD

SIL2

SIL2 Note 1

MTL4549C

 

2

4-20mA smart isolating driver + oc LFD

SIL2

SIL2 Note 1

MTL4549Y

MTL5549Y

2

4-20mA smart isolating driver + oc LFD

SIL2

SIL2 Note 1

Fire and Smoke

MTL4561

MTL5561

2

Loop-powered for fire and smoke detectors

SIL2 Note 2

TBA

Vibration

MTL4531

MTL5531

1

Vibration probe interface

SIL1

TBA

Notes

1. SIL 3 pending. Consult us

2. MTL Data Declaration only