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MECHANICAL

Enclosures

An enclosure is required to house and protect the Megablock device coupler and the

F30 Ex ic adaptor for field operation. The type of enclosure must be chosen to suit

both the hazardous atmosphere likely to be encountered and the general conditions

appropriate to its environmental exposure. For installation in hazardous areas, the

enclosure must meet the requirements of a recognised method of protection

according to IEC 60079-0. clause 1.  In addition, the following conditions should

always be considered to ensure safe and reliable operation.

a) Prevent any form of pollution that could compromise the operation.

b) Provide an adequate level of mechanical protection. This can be achieved

by selecting a protected location, a suitable enclosure, or a combination of

both.

c) Ensure that all cable entries and connections are secure by making

provision for the careful routing and securing of all cables.

d)Provide adequate security against unauthorized interference.

e) Conform to the permitted ambient operating temperature range of  –40°C to +70°C.

The F30 adaptor

The F30 adaptor is connected in series with the trunk wiring to the Megablock (see

Figure 2.1) and limits the voltage to ensure that the ‘Uo’ at the Megablock spurs is

less than the 17.5V value required for compatibility with FISCO-certified instruments.

Where the voltage arriving at the F30 is higher than this (for example, if the trunk

cable is only short in length resulting in only a small voltage drop in the cable), the

F30 regulates the voltage to less than 17.5V.  Final current limiting for each spur is

provided by the short-circuit limiting circuits built in to the F300 Megablock, for which

Ex ic approval already exists. As a result, the combination of F30 and F300 meets the

requirements for Ex ic voltage and current limitation.

The F30 is designed for use only with MTL F304. F308 and F312 Megablock types,

typically providing up to twelve Ex ic spurs per fieldbus segment.  These spurs

may be all from one F312 Megablock in one enclosure, or distributed between two

separate enclosures – see Section 4.7.

The spurs are compatible with FISCO and Entity certified fieldbus instruments, and

where FISCO instruments are selected, cable parameter calculations are not required.

Power supplies

For Ex ic spur applications, the F30 and associated Megablock must be supplied by

9192-FP power supply modules in simplex or redundant configuration. The 9192

FP module has the necessary voltage limiting and is designed to fit on one of the

backplanes from the 918x-x2 range of fieldbus power supply systems, all of which

are capable of providing n+1 redundancy for maximum availability.

The 918x family of redundant power supplies contains a range of solutions to suit

different host interfaces, consult Eaton for the model appropriate to the host and

install the chosen model in accordance with the instructions provided with it.

DESCRIPTION

The Ex ic concept

In May 2013 the Ex nL certification method was removed from the IEC60079-15

standard, and replaced by intrinsic safety method Ex ic in IEC60079-11.  Although Ex

ic and Ex nL are broadly similar, Ex ic brings with it additional requirements that are

associated with the wider intrinsic safety approach.

Ex ic is a new level of protection under the intrinsic safety protection method,

suitable for use in Zone 2 only, where Ex ic circuits may be ‘live-worked’ in the

presence of a flammable atmosphere.  It follows the same energy-limitation principles

as all intrinsically safe circuits, but safety is maintained only in ‘normal operation’.

Host H1 control system

In a typical network installation using the F30 Ex ic Adaptor, F300 Megablock and

9192-FP power supply module, the H1 interface of the host control system is

electrically connected in parallel with the fieldbus trunk circuit. The H1 interface

and host control system are not required to carry hazardous area certification in

this application, but they must comply with electrical safety standards IEC61010 or

IEC60950.  Apparatus carrying a CE mark will comply with this requirement. This

requirement also applies to any other apparatus that is connected electrically in

parallel with the fieldbus trunk circuit.

OVERVIEW

This manual explains the installation and maintenance procedures for the F30 Ex ic

Adaptor and should be read in conjunction with the product datasheet that contains

the electrical data.

The F30 Ex ic Adaptor is an accessory that works with MTL F300 range of DIN-rail

mounted, passive device couplers and extends their usage by enabling them to

provide Ex ic spur connections in Zone 2 hazardous areas. The F300 device couplers

provide a simple means of connecting a group of local field devices to the network

trunk cable that carries the signal and provides the necessary power supply.

This manual also introduces the concept of the Ex ic intrinsic safety method of

protection and explains how it applies to the F300 device couplers and the F30 Ex ic

adaptor.  Other topics will include the trunk power supply and suggested enclosures

for housing the adaptor and hubs in the hazardous area.

NOTE

The user/installer should also refer to the following datasheets and installation manuals:

• F300 range of Megablocks data sheet, EPS F300

• F300 range of Megablocks installation manual, INM F300

• 918x  Redundant Power Supply data sheets, EPS 918x

• Redundant Power Supply installation manuals, INM 918x in order to obtain

details of their installation, operating parameters and usage.

Overview

Certifications and compliances

• For a complete listing of certification and approvals across our MTL Megablock range,

download the product datasheets in the resources section of this family page.

Design features

• A green power LED on each unit indicates whether at least 9V dc is present.

• Available in two, four, eight, ten and twelve drop versions

• Multiple Megablocks are easily wired to one another to allow larger segments to be

constructed

• Choice of rising cage-clamp screw terminal or spring clamp type connections simplifies

commissioning and maintenance

• Available with built-in SpurGuard™ protectors that prevent a short circuit in any of the

individual transmitters or spur

cable runs from bringing the entire fieldbus segment down

• A red LED near each spur connection indicates that a spur is shorted and is in

“over-current” mode

Standard materials

• Housing:  Polycarbonate

Crouse-Hinds series MTL Megablock™ is a DIN-rail mounted passive hub

designed for use in FOUNDATION™ fieldbus H1 and Profibus PA networks.

Megablocks minimize hand wiring and allow individual devices to be added

to and removed from the segment without disrupting network communication.

The SpurGuard™ option provides short circuit protection for the segment.

Hazardous area approvals permit installation in a variety of configurations in

Zone 1 or 2 and Division 1 or 2. Within Zone 2 or Division 2. Megablocks may

be installed as part of non-sparking (non-arcing) or energy-limited

(non-incendive) circuits.

• F2xx-IS models: Intrinsically Safe Megablocks for Zone 1 applications

• F2xx-XE models: Megablocks for Zone/Div 1 applications

• F300 models: Megablocks for Safe Area and Zone/Div 2 applications

CERTIFICATION

MTL7000 Series barriers protect devices located in all normally

occurring explosive atmospheres, including air/flammable gas

mixtures, dusts and fibres.  MTL7000 Series barriers are certified [EEx

ia] IIC (except MTL7129P+, certified IIB) BY BASEEFA to CENELEC

standards, by FM in the USA, CSA in Canada and also by other

authorities, providing worldwide certification. MTL7000 Series

barriers are designed to the same safety descriptions as MTL700

Series equivalents (in some cases slightly stricter) and can therefore be

used for the same applications.

HOW THEY WORK

All MTL7000 Series barriers are based on the same simple principle.

Each channel contains three stages of Zener or forward-connected

diodes and an ‘infallible’ terminating resistor. In the event of an

electrical fault in the safe area, the diodes limit the voltage that can

reach the hazardous area and the resistor limits the current: active

output-current limiting circuits are not used. An internal fuse protects

the diodes, and the three stages of voltage limitation ensure continued

safety if the first or second stage should fail. MTL7100 barriers have

an additional replaceable fuse which protects the internal fuse.

The MTL7000 Series includes seven key barrier types which cover the

majority of applications, simplifying barrier selection and the

maintenance of spares stocks.

Secondary replaceable fuse versions of

many barriers are available and form the

MTL7100 sub-series. These are useful where there is

a possibility of faults occurring during commissioning

which would otherwise blow the barriers’ internal

safety fuses. One secondary replaceable fuse for

each barrier channel is provided and is lower in

value than the related safety fuse. Fuses are

packaged in small mouldings which can be latched

in a ‘disconnect’ position to break the safe and

hazardous areas during commissioning,

maintenance or fault finding, thus avoiding the need

for additional disconnect terminals.

Where a fuse is less likely to be

necessary, the MTL7200 sub-series uses a latching

out link only, to provide the basic loop disconnection

of the MTL7100 sub-series.

SUB-SERIES

MTL7000 Series barrier circuits are based on the well-proven designs

originally developed for the MTL700 Series. To simplify identification

for those familiar with the latter, part numbers are the same for

equivalent barriers, but with a ‘0’, ‘1’ or ‘2’ inserted after the initial

‘7’ to identify the relevant sub-series:

MTL7000 standard

MTL7100 fuse-disconnect

MTL7200 link-disconnect

◆ Exceptionally high packing densities – only 7mm barrier width

◆ 24V dc supply connections simplified – optional power comb

feeds many barriers

◆ Direct connection of cable screens and 0V lines – third terminal

on both hazardous and safe sides

◆ Patent US 5838547

MTL7000 Series award-winning, intrinsic safety shunt-diode

safety barriers are innovative devices designed to provide

exceptionally high packing densities, straightforward

‘single-operation’ installation and simplified

connection, commissioning and maintenance

facilities. Many of the MTL7000 Series features

duplicate the functions of conventional field terminals

and the barriers can, therefore, ‘double up’ as

terminals for many applications, saving even more space.

A barrier width of only 7mm enables

maximum packing densities due to the use of surface

mount and thick-film hybrid circuit technologies

(subjects of patent applications).

Barrier identification is provided by one or both

of two methods. The first consists of tagging strips

mounted on posts located at each end of a row of

barriers while the other consists of separate

identifiers attached to the tops of individual barriers.

Of these, the first can be used to tag locations as well

as barriers and is recommended for large

installations while the second is better suited to

installations of a few barriers only.

An optional power comb simplifies

installations where multiple barriers are powered

from a common 24V dc source (via a power feed

module or a dummy barrier). The comb replaces

individual power supply connections to each barrier,

yet allows single barriers to be removed without

affecting the others. The power feed module powers

up to 40 barriers and incorporates a trip which

switches off the supply to the barriers if a fault (such

as an overvoltage) occurs in the power source

circuit.