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Fieldbus. Accessing all Areas. Scope of presentation. Safe Area Applications. Non-Arcing Systems. Zone 2. Non-Incendive Systems. Zone 2. FNICO. Zone 2,1,0. Intrinsic Safety Systems. FISCO. Non-hazardous area. Fieldbus Host. T. T. 18-30 volt Power. Generalised Fieldbus connection.

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slide1

Fieldbus

Accessing all Areas

slide2

Scope of presentation

Safe Area Applications

Non-Arcing Systems

Zone 2

Non-Incendive Systems

Zone 2

FNICO

Zone 2,1,0

Intrinsic Safety Systems

FISCO

slide3

Non-hazardous area

Fieldbus

Host

T

T

18-30 volt

Power

Generalised Fieldbus connection

Hub

  • General fieldbus application in safe area
    • terminated at both ends of bus
slide4

Non-hazardous area

Fieldbus

Host

T

T

18-30 volt

Power

Non-hazardous area

Hazardous area

Fieldbus

Host

T

T

T

T

Generalised Fieldbus connection

Hub

  • Need for hazardous area protection
    • suitable certified interface applied
mtl5995 power supply
For general purpose applications in 31.25 kbit/s fieldbus systems

terminate at both ends of fieldbus

switched internal terminator option

Isolated power conditioning

19V, 350mA output

Suitable for Safe Area & Hazardous Area applications

Certified for installation in Zone 2 hazardous areas

Needs suitable certified interface eg, MTL791, for intrinsically safe field connection

MTL5995 Power Supply

ATEX II 3 G

EEx n A IIC T4

redundant fieldbus power system
Redundant Fieldbus Power System
  • Backplane connects to :
    • bus terminator
    • input power supplies
    • host system
    • fieldbus trunk
    • alarm circuitry
  • Load sharing by redundant supplies
  • Up to 8 units may be daisy-chained
    • with common alarm
    • carrier jumper supplied
  • version without segment terminator available
slide7

Fieldbus

Host

T

System

Alarm

Supply

‘A’

Supply

‘B’

18-30 volt

Power

Fieldbus

Redundant Fieldbus Power System

  • Power Conditioning
    • high impedance to fieldbus network
  • Redundant DC Power Inputs
  • Power Isolation to fieldbus
    • 250 V ac galvanic isolation
  • Redundant Output Power
  • 25 Volt, 350mA output per module
  • LED indicates bus is powered
  • Hot-swappable
    • modules & / or input supply can be replaced without affecting fieldbus operation
  • Alarm Circuitry
    • input power or unit failure
    • galvanic isolation from other functions
  • Certification
    • FM Class 1 Div2
    • ATEX II 3 G EEx nA IIC T4
      • Zone 2 Mounting
slide8

Common connections

within addressing

limitations

Fieldbus

Host

Fieldbus

Host

System

Alarm

T

T

Supply

‘A’

Supply

‘B’

18-30 volt

Power

Fieldbus

Fieldbus

Redundant Fieldbus Power System

redundant fieldbus power system1
Redundant Fieldbus Power System
  • Note :
    • the fieldbus connection is certified as non-arcing EEx nA IIC T4
    • It is NOT a FISCO / FNICO field connection
    • an added interface would be necessary to achieve this end
slide10

Hazardous area

Safe area

MTL5053

T

T

31.25kbit/s fieldbus

MTL5053 Isolator / Power Supply

  • The MTL5053 extends 31.25kbit/s fieldbus networks into hazardous areas
  • Provides power to the highway & for communication to field devices
  • Separate power may be required for safe-area field devices
  • Supply voltage 20 to 35Vdc
  • Isolation : 250V ac between
    • safe area fieldbus circuits
    • hazardous area fieldbus circuits
    • power supply
  • Provides 18.4 volts at max 80 mA
  • Safety description 22V, 102, 216mA
  • Isolator transparent to fieldbus, hence termination at isolator is not a pre-requisite
  • Switchable safe area terminator

Ex II (1) GD

[EEx ia] IIC

some definitions

Safe Area

system

NA

system

NI

system

Some definitions

Zone 2

Zone 1

Zone 0

Safe area

Division 2

Division 1

Non-Arcing Systems

Non-Incendive Systems

slide12

Ethylene group

Propane group

Methane group

Hydrogen group

The principle of

live working

Limit the energy

in the circuit

Current

Power = volts x amps

Resistive Curves

Voltage

slide13

Hydrogen group

230 mA

Apply a

Safety Factor

24 Volts

Safety Factor

Unity : Zone 2

1.5 : Intrinsic Safety

Fault-tolerant

components not required for Zone 2

Current

Resistive Curves

Voltage

types of circuit in zone 2

NON-ARCING CIRCUITS :

  • High energy & mains circuits
  • No systems concept
  • Not live-workable
Types of circuit in Zone 2

NON-INCENDIVE CIRCUITS :

Energy-limited

  • Unity Safety Factor
  • Low energy circuits
  • Systems concept
  • Live-workable
  • User must NOT permit arcing
complete hazardous area capability

Safe Area

system

NA

system

NI

system

IS

system

Zone 0

system

Complete hazardous area capability

Safe area

Zone 2

Zone 1

Zone 0

Unclassified location

Division 1

Division 2

safe area or non arcing installation

Max output :

    • 32 V
    • 1.5 A
  • MTL5995
  • FPS-I
Safe Area or Non Arcing Installation
  • Live working NOT permitted in a hazardous area
  • Installation in => IP54

‘nA’

  • All trunks & spurs
    • EEx nA IIC T4
    • Vmax 32 V
    • Imax 1.5 A

‘nA’

  • System Certification :
    • Ex nA IIC T4
    • Class 1, Div 2, Groups A,B,C,D, T4
  • FF-816 specification :
    • 32 V
    • 1.5 A
  • Terminator : FBT-1
    • Vmax 32 V
non incendive spurguard legs

Max output :

    • 32 V
    • 1.5 A
  • MTL5995
  • FPS-I
Non Incendive / ‘Spurguard’ legs
  • Live working NOT permitted on ‘nA’ trunk
  • Installation in => IP54

‘nA’

  • Main trunks :
    • EEx nAL IIC T4
    • Vmax 32 V
    • Imax 1.5 A

‘nL’

  • Spurguard legs :
    • EEx nL IIC T4
    • Vmax 32 V
    • Imax 60 mA

‘nA’

‘nL’

  • Live working safe on ‘NI’ spurs
  • System Certification :
    • Ex nA [nL] IIC T4
    • Class 1, Div 2, Groups A,B,C,D, T4
  • FF-816 specification :
    • 32 V
    • 1.5 A
  • Terminator :
    • Vmax 32 V
non incendive system
Non Incendive System
  • Live working permitted throughout
  • Installation in => IP54
  • MTL9111
  • Max output :
    • 14 V
    • 233 mA

‘nL’

‘nL’

  • All trunks & spurs
    • EEx nL IIC T4
    • Vmax 14 V
    • Imax 233 mA

‘nL’

  • MTL9112

option for IIB

with appropriate

safety parameters

‘nL’

  • System Certification :
    • Ex nL IIC T4
    • Class 1, Div 2, Groups A,B,C,D, T4
  • Terminator :
    • Vmax 32 V
non incendive spurguard legs1
Non Incendive >> ‘Spurguard’ legs
  • Live working permitted throughout
  • Installation in => IP54
  • MTL9111
  • Max output :
    • 14 V
    • 233 mA

‘nL’

  • All trunks & spurs
    • EEx nL IIC T4
    • Vmax 14 V
    • Imax 233 mA

‘nL’

  • Spurguard legs
    • EEx nL IIC T4
    • Vmax 14 V
    • Imax 60 mA

‘nL’

  • MTL9112

option for IIB

with appropriate

safety parameters

‘nL’

  • System Certification :
    • Ex nL IIC T4
    • Class 1, Div 2, Groups A,B,C,D, T4
  • Terminator :
    • Vmax 32 V
intrinsically safe non fisco installation

into Zone 0

Intrinsically Safe (Non-FISCO) Installation
  • Live working permitted throughout
  • Installation in => IP54

‘IS’

  • MTL5053

‘IS’

  • Available output :
    • 18.4 V 80 mA
  • Safety parameters :
    • 22 V 216 mA

‘IS’

‘IS’

  • System Certification :
    • Ex ia IIC T4
    • Class 1, Div 1, Groups A,B,C,D, T4
  • Terminator :
    • Vmax 24 V
    • Imax 250 mA
  • FF-816 specification :
    • 24 V
    • 250 mA
intrinsically safe fisco installation
Intrinsically Safe (FISCO) Installation
  • Live working permitted throughout
  • Installation in => IP54

‘IS’

  • MTL9121 IS : IIC
    • 14.0 V
    • 180 mA
  • MTL9122 IS : IIB
    • 14.8 V
    • 380 mA

‘IS’

  • Megablock rating :
    • Vmax 14.8 V
    • Imax 380 mA

‘IS’

‘IS’

  • System Certification :
    • Ex ib IIC T4
    • Class 1, Div 1, Groups A,B,C,D, T4
  • Use in appropriate gas group
  • Limited to Zone 2 & 1
  • All devices to be approved for FISCO
  • Terminator :
    • Vmax 24 V
    • Imax 250 mA
slide23

Network

Calculations

slide24

T

T

T

T

Multiple power supply configuration

Host

  • Sufficient current capacity ?
slide25

T

T

T

Basic configuration

9121 & 9122

Host

L

N

E

24V

supply

Host trunk

2- 3+

4- 5 S 6+

T

Safe Area

7+ 8 S 9 -

Zone 1 / Div1

Hazardous Area

6 devices (120 mA) in IIC

13 devices (260 mA) in IIB

if 20 mA consumption each device

slide26

T

T

T

T

  • The Fieldbus signal, which is superimposed on the IS voltage, is fed via the interface device to & from the field devices
  • The 24 volt power supply is converted to an intrinsically safe supply to feed the IS trunk

Host

Power

& data

L

N

E

24V

supply

2- 3+

4- 6+

Safe Area

7+ 8 S 9 -

Zone 1 / Div1

Hazardous Area

slide27

8913

8914

Power

Units

Zone2 / Div2

Mains

5991

Power

Unit

T

T

T

T

Safe

Area

Mains

Mains or 24-volt

power supply

Host

Power consumption

9121 : 190mA

9122 : 300mA

8914 : 10 A

5991 : 2 A

slide28

Model Apparatus Useable

Number Class Output

V mA

9121-IS IIC 12 120

9122-IS IIB 12.8 260

Design Parameters

  • System design determined from :
    • power supply output voltage
    • power supply available current
    • knowledge of current consumption of each field device
      • survey shows a range of 10 to 28 mA
      • 20 mA is assumed
    • application of Ohm’s Law to the cable network
    • assessment for adequate voltage at each field device
  • Line resistance of 50 /km is assumed
    • within the FISCO range of 15 to 150 /km

Parameter Value

Loop resistance 15 ohm to 150 ohm / km

Loop inductance 0.4 mH to 1 mH / km

Capacitance 80 nF to 200 nF / km

Spurs are in addition to permitted maximum cable length

FISCO cable parameters

slide29

Model

9121-IS : IIC

Useable

Output

V mA

12 120

3 volts

100 mA

Hydrogen

Gas Group

Typical IIC calculation

5 connected

field devices at end of trunk

Eg :

 I = 100 mA

600 metres

30 

= 3 volts

12 volts

If current drawn < 20 mA then instrument population can be increased

600 metre

IS trunk

30m spur

= 1.5 

carrying 20 mA

volt drop

= 30 mV

9 volts

NODE

each

instrument

draws 20 mA

600 metre

IS trunk

T

slide30

Model

9121-IS : IIC

Useable

Output

V mA

12 120

T

9.25 V

Hydrogen

Gas Group

Typical IIC calculation

5 distributed

field devices

12 volts

 I = 100 mA

12.5 

= 1.25 volts

each

instrument

draws 20 mA

250 metres

10.75 V

 I = 80 mA

12.5 

= 1.0 volt

250 metres

9.75 V

 I = 40 mA

12.5 

= 0.50 volts

250 metres

750 metre

IS trunk

slide31

Model

9122-IS : IIB

Useable

Output

V mA

12.8 260

3.8 volts

240 mA

Ethylene

Gas Group

Typical IIB calculation

12 connected

field devices at end of trunk

 I = 240 mA

= 3.8 volts drop

thru 316 metres

of 15.8 

12.8 volts

316 metres

316 metre

max

IS trunk

12

instruments

each

drawing

20 mA

9 volts

NODE

Trunk length will increase if device population is reduced

T

slide32

24

volts

Power,

Repeater &

Ex protection

Power drawn

in either direction

1.8 kms

316 metres

24

volts

Power Supply as a IIB Repeater

Safe Area

Zone 2 / Div 2

Zone 1 / Div 1

316 metres

Power &

Ex protection

only

12 instruments

Cable protection

required

A similar scenario exists for a IIC repeater

slide33

Power drawn

in either direction

Power Supply as a Repeater

Safe Area

Zone 2 / Div 2

Zone 1 / Div 1

  • Host probably has no Ex protection in powering the 912x device :
    • Cable is a non-arcing circuit due to incendive level of energy
    • Cable protection required - hazardous area wiring may not be disconnected to reveal floating wires
    • Repeater terminals carry limited energy; hence circuit is non-incendive and power plug may be removed
  • 912x device may power host equipment (max 30 mA) and power plug may be removed

Power,

Repeater &

Ex protection

1.8 kms

slide34

The ‘CE’ Mark

Confirms compliance with all

relevant Community directives

Conformite European

ex

The ‘Explosive Atmosphere’ Mark

Confirms compliance with

ATEX

or previous

Flammable Atmosphere Directive

ATEX Certification

equipment marking 9121 power supply

Referenced to ambient

of -20 to +40 OC unless

indicated as above

  • Temperature Class (Group II)
  • Apparatus Group (Hydrogen)

T1 : 450 OC

T2 : 300 OC

T3 : 200 OC

T4 : 135 OC

T5 : 100 OC

T6 : 85 OC

  • Type of protection code
  • Explosion protection symbol
  • Conformity with European Standard
Equipment Marking - 9121 Power Supply

CENELEC / IEC

[E Ex ib] IIC T4 -40 OC < Tamb < +70 OC

equipment marking 9121 power supply1

Referenced to ambient

of -20 to +40 OC unless

indicated as above

  • Temperature Class (Group II)
  • Apparatus Group (Hydrogen)

T1 : 450 OC

T2 : 300 OC

T3 : 200 OC

T4 : 135 OC

T5 : 100 OC

T6 : 85 OC

  • Type of protection code
  • Explosion protection symbol
  • Conformity with European Standard
Equipment Marking - 9121 Power Supply

CENELEC / IEC

[E Ex ib] IIC T4 -40 OC < Tamb < +70 OC

[ ] indicates the apparatus is safe area

mounted ‘associated apparatus’ suitable

for connection to Ex ib equipment

equipment marking 9121 power supply2

G : Gas, vapour, mist

D : Dust

0600

  • Type of explosive atmosphere (Group II)

II (2) GD

M1 : energised

M2 : de-energised

1 : Zone 0, 20

2 : Zone 1, 21

3 : Zone 2, 22

  • Equipment Category

I : Mining

II : Non-Mining

  • Equipment Group
  • EU Explosive Atmosphere Symbol
  • Ref to Notified Body responsible for testing
  • CE mark
Equipment Marking - 9121 Power Supply

ATEX

9121 baseefa certification

0600

II (2) GD

9121 - BASEEFA Certification

ATEX

[E Ex ib] IIC T4 -40 OC < Tamb < +70 OC

CENELEC / IEC

BAS 02 ATEX 7276

EC-type examination

certificate

ATEX Category 2 certification

  • Additional information on product :

Safety parameters, where applicable

Year of manufacture & Serial No.

Name & address of manufacturer

Manufacturers type identification

9121 mtl declaration of conformity

II 3 GD

9121 - MTL Declaration of Conformity

ATEX

E Ex nA IIC T4 -40 OC < Tamb < +70 OC

CENELEC / IEC

MTL 02 ATEX 9121X

MTL Declaration of Conformity

ATEX Category 3 certification justifying

mounting the 9121 power supply in Zone 2

9121X refers to special conditions of use : > power supply is installed in an appropriate enclosure > it must be protected from large supply transients

slide40

0600

II (2) GD

9122 - BASEEFA Certification

ATEX

[E Ex ib] IIB T4 -40 OC < Tamb < +70 OC

CENELEC / IEC

BAS 02 ATEX 7277

EC-type examination

certificate

ATEX Category 2 certification

slide41

II 3 GD

9122 - MTL Declaration of Conformity

ATEX

E Ex nA IIB T4 -40 OC < Tamb < +70 OC

CENELEC / IEC

MTL 02 ATEX 9122X

MTL Declaration of Conformity

ATEX Category 3 certification justifying

mounting the 9122 power supply in Zone 2

slide42

YES

9321-SC

Fieldbus Intrinsically Safe Concept (FISCO)

  • Adopting FISCO raises the issue :
  • Can Entity certified fieldbus equipment (non-FISCO) be incorporated into a FISCO network ?

9323-SC

slide43

I.S. Entity Spur Connections

(non-FISCO devices)

9321-SC

Zone 1

Entity IS certified

device

9121-IS : IIC

output safety

parameters :

14 V; 180 mA; 2.52 W

deliver 12.0 V; 110 mA

9321-SC

Entity spur connector

EEx ib IIC T4

II 2 (2) G

Live working

throughout

FISCO

devices

HUB

Entity device to FF-816 has

an input safety description of

24 V; 250 mA; 1.2 watts

T

slide44

YES

9322-SC

Fieldbus Intrinsically Safe Concept (FISCO)

  • The use of active current limitation restricts the categorisation to ‘EEx ib’, ie, connection to Zone 1 only
    • Can a fieldbus device be installed in a Zone 0 by adding further protection to achieve ‘ia’ status ?
slide45

9322-SC

Zone 1

ia : Zone 0

energy limit

Zone

0

T

Networking into Zone 0

9322-SC

Zone 0 spur connector

Useable

with either

9121-IS : IIC

9122-IS : IIB

II 2 (1) G EEx ib IIC T4

II (1) G EEx [ia] IIC

FISCO

devices

NODE

slide46

Wiring

Components

slide47

Wiring Components - Megablock Series

  • Megablocks :
    • DIN-rail mounting Fieldbus network hubs
    • connect multiple field devices to trunk network
      • minimise hand wiring
    • network integrity maintained during connection / disconnection of individual devices
    • LED indicates minimum 9 volts present at hub
    • Megablocks available in 2, 4 & 8-way (10-way) versions
    • Megablock terminator available

Terminator

  • Short-circuit protection option using SpurGuard
slide48

Megablock Series

Trunk /

Home run

Power LED >= 9V

Field

device

connection

Optional

SpurGuard

short circuit protection

- visual indication of fault

Trunk /

Home run

Securable, pluggable connectors

8-way

Megablock

megablock series
4 + 8 drop = 12 drop

Easy to retrofit

Junction box for specific application

Megablock Series

Choice of junction box

Use site standard

suitable for environment

trunk

standard

instrument cable

spur

terminator

slide50

Relcom SpurGuards™

  • System reliability and availability may be affected
    • by the shorting of the fieldbus highway,
    • by the failure of any individual fieldbus device,
    • thus interrupting data communication across the entire bus segment
    • could occur during installation or routine instrument maintenance
  • A SpurGuard™ is a current-limiting device that provides short circuit protection to the fieldbus segment
  • By attaching a SpurGuard™ at each point where a field device is attached to the segment home run cable, isolation of the network from individual device failures is achieved
  • SpurGuards™ are available with any Megablock
    • a red LED indicates when a SpurGuard™ is providing overcurrent protection
  • Because a SpurGuard™ leg draws power from the segment when in short circuit mode, their short circuit current consumption must be taken into account during segment design
  • The SpurGuard™ short-circuit current is nominally 60 mA
  • Trunk to Spur max. voltage drop = 0.4 volts
slide52

Lightning Strikes

Handling

the

effect

slide53

I (100 kA)

PK

90%

50%

10%

t

8µs

20µs

Lightning Strikes

  • There is no remedy for direct lightning strikes
    • the energies involved are too high
    • but measures can be taken to minimize the effects of near-lightning strikes on Fieldbus networks
  • Lightning is a short burst of very intense voltage and current.
    • Even when a direct lightning strike is shunted to ground by a lightning rod, it induces high voltages and currents in metal components nearby eg, the conductors & shield of Fieldbus cable
  • The purpose of lightning surge protection in Fieldbus wiring is to minimize the induced voltages & currents and hence to minimise damage to Fieldbus equipment
    • a lightning strike might produce 100,000 Amps in a lightning rod
    • induced currents in nearby grounded metal objects may be several thousand Amps
    • induced current in the shield of a fieldbus cable might be several hundred Amps
slide54

Flash-over

100kA

Local Ground

Strike

Flash-over

Fieldbus

High localpotential on

building earth

system

High potential across insulation on field instrument

Local ‘ground’

Principles & Practicalities

Induced Voltage V = L x I/ t

slide55

Centralised control

equipment

Shield

Transient Surge

Suppressor

Transient Surge Suppression

  • The shield of the Fieldbus cable is grounded
    • but according to the installation standard, in only one place
  • Single-point grounding eliminates current loops in the shield
    • reduces induced noise in the signal concerned
    • is a pre-requisite for an intrinsically safe circuit
    • the shield is normally grounded at the control room
  • Any lightning strike in the field could produce a large current in the shield that needs to travel to the control room to pass to ground
    • in a long network a large shield voltage could occur
    • by capacitive coupling a large voltage might appear on the internal twisted pair
  • A surge may be minimized by using a Transient Surge Suppressor
slide56

Differential Voltage Suppression

  • The next consideration is to minimize the voltage that might be induced in the twisted-pair inside the shield
  • Due to the capacitance between the shield & each of the wires in the twisted pair,
    • a voltage change on the shield will induce a voltage on the wires
  • Using twisted-pair cable, the shield-to-wire capacitances for the two wires are nearly equal
    • hence the voltage induced in each of the wires in the twisted pair will be identical (Common Mode Voltage effect)
  • The Fieldbus standard requires that the common mode immunity of Fieldbus devices should be of a high order, eg, Surge Protection Devices :
      • FP32 = 225 volts DC trigger point
      • TP32 = 120 volts DC trigger point
slide57

Protection Devices

  • The FP32 surge protection device prevents surges & transient overvoltages conducted along the Trunk or Spurs of fieldbus systems from damaging the associated electronics
    • may be used at any point on a Trunk to safely divert any surges to ground
  • The TP32 is the protection equivalent installed at an instrument
  • Fully automatic in operation, the devices react instantly to make sure that equipment is never exposed to damaging surges between lines or between lines & earth
    • Reacting instantaneously to surges they then reset automatically

FP32 TP32

slide58

Line

inductors

Circuit fuses

Signal

lines

Protected

equipment

Gas

discharge

tube

Circuit

earth

Solid-state

limiters

Surge Protection Device

I (100 kA)

PK

90%

  • The multi-stage elements of the FP32 / TP32 use a combination of solid state electronics and a gas filled discharge tube (GDT) to provide surge protection up to 20kA

50%

10%

t

20µs

slide59

Power problems due to transient spikes

Surge < 10%

Sag < 10%

Outage < 1%

Transient 85% to 90%

slide60

Power

conditioner

Hub

T

T

Trunk

Terminator

Generalised Fieldbus connection

Power

supply

Power

distribution

panel

Incoming

AC supply

slide61

FP32

MA 4000

Host System protection

Power

conditioner

Hub

T

T

Trunk

Terminator

Power

supply

Power

distribution

panel

Incoming

AC supply

slide62

FP32

Field Device Protection - ‘compact’

Hub

Trunk

T

Terminator

  • All spurs less than :
    • 50m horizontal or
    • 10m vertical
  • Surge invasion from host end of trunk
  • all devices are protected by one surge protection device in trunk

Spurs

< 50m horizontal

< 10m vertical

slide63

FP32

Field Device Protection - ‘widespread’

Hub

Trunk

T

Terminator

Spurs

> 50m horizontal

> 10m vertical

  • Spurs greater than :
    • 50m horizontal or
    • 10m vertical
  • surge invasion from Host end of trunk
  • surge protection installed to each device