1

Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

The Intrinsically Safe

High Power Trunk

Thomas Klatt

Pepperl+Fuchs GmbH

Business Development Manager

E-mail: tklatt@de.pepperl-fuchs.com

Phone: +49 621 776 2130

Multaqa 2011, Abu Dhabi

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Agenda

Developments of fieldbus in hazardous area

application

Purpose of the new concept

Topology of an intrinsically safe high power trunk

Technical values

Validating of intrinsic safety

Conclusion

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Enhancements in Fieldbus Technology

Ex-i (Entity) Concept

Very low No. of instruments, very

short trunk cable length, complex

proof of intrinsic safety

• Developed early 90’s

Ex-i (FISCO) Model

Low No. of instruments, short trunk

cable length, simple proof of intrinsic

safety

• Delevoped late 90’s

High Power Trunk Concept

Change-over to IS in the field

In acc. with FISCO Model

Redundancy for the first time

• Developed 2000s

Physical layer for hazardous area application

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Limitation of Full FISCO

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Purpose of a new concept

Provide a choice combining

FISCO's Simplicity of intrinsic safety with the

Benefits of the High-Power Trunk:

Cable distance

High device count

Real power supply redundancy with load

sharing

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Realization of IS today (simplified)

In case the input voltage is too high the Zener-diode becomes

conductive and the fuse will blow

The Zener-diode limits the max. voltage available to the field

The resistor limits the max. current available in the field

This is a power limitation

Sparks will be avoided

IS today

Fie

ld

sid

e

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Basic idea

Ignition requires energy

Energy for gas ignitions is well known

E.g. Hydrogen 20 µJ resp. 20 µWs

Energy is

tIUW ** for DC signals

dttitutw )(*)()( for AC signals

Today the time is not considered in intrinsic

safety

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Basic idea

Interrupt the flow of power when energy

escapes the electric circuit

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Simple Circuit

Ex ib IIC

Time to turn-off: 5 to 10 µs

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Typical Spark – Physics

IF

UF

PF

Initial

Phase Critical Phase

Spark duration tF: long t

U, I,

P

di/dt

Investigated by PTB

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Typical Spark – Turned off

IF

UF

PF

Initial

Phase Critical Phase

Spark duration with Power-i tF (small)

U, I,

P

t

Investigated by PTB

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

The Power Supply – Block Diagram

S1

Rstart

V VO

I-

Detector

overcurrent

+di-

Detector

-di-

Detector

undervoltage

break spark make spark

Monoflop

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

U

I

X

Output characteristic Power Supply

1 Power Off

2 Initial On – S1 open

3 Threshold – S1 closes

4 Overload condition

Turning On

1 2

3

4

RL1

RL2 Ulim

Uthres

Ilim

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

U

I

X

Output characteristic Power Supply

Turning Off RL1

RL2 Ulim

Uthres

1

1 Switch S1 will

open in ≤ 2 µs

2 Provided power is

below the limits

safe status

2

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

General Purpose Area

Zone 2 To DCS

Zone 1

Intrinsically safe High-Power Trunk

Redundant, three-port isolated

I.S. HPT Power Supply

I.S. HPT Segment Protectors

The intrinsically safe High-Power Trunk

protected by Power-i/DART

Intrinsically safe spurs

“conventional IS”

Ex ib IIC

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Overview – Intrinsic Safety

In an I.S. High Power Trunk fieldbus application only

the TRUNK is protected by the new technology

Today's intrinsically safe field devices and standard

H1 controllers are supported!

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Comparison of Technical Data

FISCO

I.S. High

Power

trunk

High Power

trunk

Rating Ex ia IIC Ex ib IIC Ex ib IIB Ex ib IIC

Typ.

operating

voltage

12.8 V 12.4 V 13.1 V 22 V 28 V

Max. supply

current 100 mA 120 mA 265 mA 360 mA 500 mA

Compared to the FISCO solutions I.S. High Power Trunk

provides

More voltage longer cable runs

More current more instruments per segment

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Overview

I.S. High Power Trunk fieldbus

Supports trunk/spur topology

Allows up to 4 segment protectors per segment

– The limitation of IEC 61158-2 applies to IS HPT fieldbus as

well (32 communication elements per segment)

The overall cable length is limited to 1900 m

– Limitation is coming from IEC 61158-2

The trunk cable length is limited to 1000 m

– Limitation is coming from I.S. requirements

The spur cable length is limited to 120 m

– Limitation is coming from IEC 61158-2

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

I.S. High Power Trunk Fieldbus Segment

IS HPT FBPS protects the trunk

Extinguishes a spark before it becomes

incendive

Live disconnect permitted without hot work

permit

Power redundancy with load sharing

Intrinsically Safe Outputs

IS HPT wiring block:

For any existing standard fieldbus

instrument complying to the safety

parameter requirements

Short-circuit protection

=> Intrinsically Safe Ex ib IIC

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

IS HPT Fieldbus Power Supply

Redundant Power Supply with load

sharing

With Advanced Diagnostic Module

Works as I.S. Barrier with three-

way galvanic isolation of DCS,

bulk power and fieldbus segment

Technical Data

Trunk Output

Power-i/DART

Fieldbus Power

Supply

Rated power 22 V / 360 mA

DCS supply 10.2 V / 40 mA

Max.trunk cable length 1000 m

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

IS HPT Wiring Block

Connections for field instrument

Outputs intrinsically safe Ex ib IIC

With short-circuit protection

Live disconnect on trunk and spurs

Technical Data

IS HPT

wiring block

Rated power (spur) min 10.5 V @ 34 mA

IS Power rating

Trunk

Only for connection to IS HPT fieldbus

power supply

Spur (Uo / Io) 23 V / 47 mA

Spur length

(acc. to

IEC 61158 -2)

120 m (1 – 12 communication elements)

90 m (13 – 14 communication elements)

60 m (15 – 18 communication elements)

30 m (19 – 24 communication elements)

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Validating Intrinsic Safety

Four certificates will be required

Certificate for the for the I.S. fieldbus power supply

Certificate for the Motherboard of FBPS

Certificate for the Power-i/DART wiring block

System approval

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Validating Intrinsic Safety

On the Trunk – As fast as easy

Use only type 'A' fieldbus cable

Ensure trunk cable length is max. 1000 m

Use only IS HPT fieldbus power supplies and IS HPT

Segment Protectors according to the certificate

That's All! – Easy to understand, easy to engineer.

Certified ATEX and IECEx acc. to IEC 60079-11

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

<

Status of

Certification

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

About the Spurs

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Multaqa 2011,

Abu Dhabi, VAE

© 1994 – 2011 Fieldbus Foundation

Conclusion

The intrinsically safe High-power Trunk Concept…

Is certified in acc. with international standards (IEC 60079-11)

Support today's intrinsically safe instruments

Provides higher power (compared to FISCO) for

– Longer cable runs

– More instruments per segment

Features power supply redundancy with load sharing

Permits validation of I.S. without calculations

… is a solution for applications where the trunk is

required to be intrinsically safe