background image

I

f the internal diagnosis system detects a failure

,

the measuring

system goes into fault mode

.

A

dangerous undetected failure exists if the measuring system

switches neither to the de

ned safe condition nor to the failure

mode when the process requires it

.

I

f the measuring system delivers output currents of

"

fail low

"

or

"

fail high

"

,

it can be assumed that there is a malfunction

.

T

he processing unit must therefore interpret such currents as a

malfunction and output a suitable fault signal

.

I

f this is not the case

,

the corresponding portions of the failure

rates must be assigned to the dangerous failures

.

T

he stated

values in chapter

"

S

afety

-

relevant characteristics

"

can thus

worsen

.

T

he processing unit must correspond to the

SIL

level of the

measurement chain

.

I

f the demand rate is only once a year

,

then the measuring

system can be used as safety

-

relevant subsystem in

"

low

demand mode

"

(

IEC

61508

-

4

,

3

.

5

.

12

).

I

f the ratio of the internal diagnostics test rate of the measuring

system to the demand rate exceeds the value

100

,

the

measuring system can be treated as if it is executing a safety
function in the mode with low demand rate

(

IEC

61508

-

2

,

7

.

4

.

3

.

2

.

5

).

A

n associated characteristic is the value

PFD

avg

(

average

P

robability of dangerous

F

ailure on

D

emand

).

I

t is dependent

on the test interval

T

P

roof

between the function tests of the

protective function

.

N

umber values see chapter

"

S

afety

-

related characteristics

"

.

I

f the

"

low demand rate

"

does not apply

,

the measuring system

as safety

-

relevant subsystem in

"

high demand mode

"

should

be used

(

IEC

61508

-

4

,

3

.

5

.

12

).

T

he fault tolerance time of the complete system must be higher

than the sum of the reaction times or the diagnostics test
periods of all components in the safety

-

related measurement

chain

.

A

n associated characteristic is the value

PFH

(

failure rate

).

N

umber values see chapter

"

S

afety

-

related characteristics

"

.

C

on

guration of the process

-

ing unit

L

ow demand mode

H

igh demand mode

6

VEGAPULS

series

60

-

4

20

m

A

/

HART

F

unctional safety

31338

-

EN

-

070510

Summary of Contents for VEGAPULS 61

Page 1: ...Safety Manual VEGAPULS series 60 4 20 mA HART Radar...

Page 2: ...1 2 Planning 5 1 3 Instrument parameter adjustment 7 1 4 Setup 9 1 5 Reaction during operation and in case of failure 9 1 6 Recurring function test 9 1 7 Safety related characteristics 10 2 VEGAPULS s...

Page 3: ...le up to SIL2 in a single channel architecture 1oo1D and up to SIL3 in a multiple channel diverse redundant architecture The use of the measuring system in a multiple channel homogeneous redundant arc...

Page 4: ...for the process industry sector Part 1 Framework de ni tions system hardware and software requirements Failure limit values for a safety function depending on the SIL class of IEC 61508 1 7 6 2 Safety...

Page 5: ...signal is transmitted to a connected processing unit to monitor the following conditions l Exceeding a preset level l Falling below a preset level When the switching point set on the processing unit i...

Page 6: ...3 5 12 If the ratio of the internal diagnostics test rate of the measuring system to the demand rate exceeds the value 100 the measuring system can be treated as if it is executing a safety function i...

Page 7: ...t used for transmission of safety relevant information The measuring system should be used appropriately taking pressure temperature density dielectric value and chemical properties of the medium into...

Page 8: ...fter connecting the instrument the output signal jumps to the set interference current at the end of the switch on phase l In mode Simulation the signal current can be simulated independent of the act...

Page 9: ...anual If due to a detected failure the electronics or the complete sensor is exchanged the manufacturer must be informed incl a fault description 1 6 Recurring function test The recurring function tes...

Page 10: ...7 Safety related characteristics The failure rates of the electronics the mechanical parts of the transmitter as well as the process tting are determined by an FMEDA according to IEC 61508 The calcula...

Page 11: ...executable sensor software 15 h VEGAPULS 68 and VEGAPULS 61 62 63 with increased sensitivity E013 no measured value available 2 36 min depending on the application E042 E043 hardware error 4 min E036...

Page 12: ...5 years 4 PFDavg after 10 years Multiple channel architecture If the measuring system is used in a multiple channel architecture the safety relevant characteristics of the selected structure of the m...

Page 13: ...VEGAPULS series 60 4 20 mA HART 13 Functional safety 31338 EN 070510...

Page 14: ...14 VEGAPULS series 60 4 20 mA HART Functional safety 31338 EN 070510...

Page 15: ...VEGAPULS series 60 4 20 mA HART 15 Functional safety 31338 EN 070510...

Page 16: ...om www vega com ISO 9001 All statements concerning scope of delivery application practical use and operating conditions of the sensors and processing systems correspond to the information avail able a...

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