MACX MCR-EX-SL-RPSSI-I-UP(-SP)

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12

7

Safety-related applications (SIL 2)

SIL regulations apply to the following modules:

The safety-related repeater power supply and input signal

conditioners listed above are certified as conform with

DIN EN 61508-1:11.2002. Test certificate: BVS Pb 09/08

7.1

Safety function and safety demand

The device performs the safety function of electrically

isolated forwarding of a 4...20mA standard signal with a

maximum deviation of 5% maximum.

Output values outside this range of 3.6 … 21 mA are

considered as the safe state, which is detected by the

subsequent controller.

Safe failures in the device are therefore those errors where

the repeater power supply and input signal conditioner

sends an output signal that deviates from the input signal by

no more than 5%.

Dangerous, non-detectable failures are errors where the

repeater power supply and input signal conditioner does not

follow a change in the input signal or deviates from the input

signal by more than 5% and is not outside the range.

Dangerous, detectable failures are those that send a

signal outside the range (< 3.6 mA and > 21 mA).

7.2

Safety integrity requirements

Failure rates

–

Type A device (according to IEC/EN 61508-2)

–

Safety Integrity Level (SIL) 2

–HFT = 0

–

MTTR = 24 h

–

1oo1 structure

–

Ambient temperature: 40 °C

Operation as a repeater power supply

The total failure rate is 622 FIT.

The MTBF is 183 years.

The probability of a dangerous failure per hour for

“continuous demand” mode and the average probability of

failure of the specified function for “low demand” mode are

determined based on the error rates:

PFD

PFH = 5.83 * 10

-8

/h

This fulfills the requirements for the PFH value for a SIL 2

system.

The boxes marked in gray show that the calculated PFD

avg

values are within the permissible range for SIL 2 in

accordance with Table 2 of IEC/EN 61508-1. They fulfill the

requirement to not cover more than 10% of the safety circuit,

i.e., to be better than or equal to 1.00E-03.

The box marked in white shows that the calculated PFD

avg

values are within the permissible range for SIL2 in

accordance with Table 2 of IEC/EN 61508-1. However, they

do not fulfill the requirement to not cover more than 10% of

this safety circuit, i.e., to be better than or equal to 1.00 E03.

Failure limit

The data is based on an operating mode with low demand

rate. The device covers less than 10% of the PFH/PFD of

the entire safety circuit.

Figure 6

Safety circuit

Designation

Order No.

MACX MCR-EX-SL-RPSSI-I-UP

2865793

MACX MCR-EX-SL-RPSSI-I-UP-SP

2924029

MACX MCR-SL-RPSSI-I-UP

2865968

MACX MCR-SL-RPSSI-I-UP-SP

2924210

λ

SD

λ

SU

λ

DD

λ

DU

SFF

DC

D

0 FIT

557.7 FIT

0 FIT

58.3 FIT 90.55%

0%

T

1 year

3 years

4 years

PFD

2.53E-04

7.66E-04

1.02E-03

Sensor

25%

Device

< 10%

Processing

15%

Actuator

50%