Enclosure for potentially explosive atmospheres

What is ATEX?

 

 It is a term commonly used to describe potentially explosive atmospheres

(ATmosphères EXplosibles in French) and standards for protection systems

and equipment.

 

 Two European directives, ATEX 99/92/CE and ATEX 94/9/CE, and

international standards IEC 60079 and IEC 61241, harmonized with

EN European standards, apply to this field.

 

How is an potentially explosive atmosphere defined

according to ATEX?

 

 An potentially explosive atmosphere is defined as a mix of flammable

substances in the form of gas, vapour, dust (cloud or deposit) which, in air

and under normal atmospheric conditions, can completely or partially catch

fire in the form of an explosion when exposed to a source of ignition.

 

Equipment for potentially explosive atmospheres

Degree of protection In hazardous areas, equipment is required to

offer a minimum degree of protection of IP54, but it can be tested or

certified with a higher degree of protection.The final solution must be certified by a notified body

 

 Since 1st July 2003, European directive ATEX 94/9/CE has made it compulsory to use certified electric or

non-electric equipment when it must be installed in zones with explosive atmospheres (gas or dust).

 Certification must be provided by a body which is notified according to the same directive.

 The body notifies its assessment of the quality of the production and certifies that the product complies

with the health and safety demands defined in the directive and the international standards.

 The certificate shows the category of the product by marking, and thus the zone and atmosphere in

which it can be used.

 The standards define the following types of protection for electric equipment:

Enclosures are certified as components. They will be assembled with other ATEX electrical, pneumatic

and hydraulic components, among others to form a final solution which, in turn, must be ATEX-certified

and subject to a declaration of conformity

 

More info.

http://www.schneiderelectric.pt/documents/product-services/involucros-universais/ATEX.pdf

 

Control Panel - Technical Guide - How can the deterioration of electrical equipment installed in an outdoor enclosure be prevented?

DOWNLOAD :

 

http://download.schneider-electric.com/files?p_Reference=CPTG004_EN&p_EnDocType=Technical%20leaflet&p_File_Id=18000086&p_File_Name=CPTG004_EN+%28web%29.pdf

 

ASTA Type Test Certification

ASTA Type Test Certificates provide authoritative objective evidence that your bespoke equipment is compliant to relevant safety standards. The certificate can be used for supporting technical files related to CE Marking for the European Union.

ASTA Type Test Certification is best suited for low volume or ‘bespoke’ equipment. ASTA Type Test Certification provides you with an independent compliance test certificate for one or a number of samples when tested against the requirements of the product safety standard. The document issued is known now as an ‘ASTA Type Test Certificate.’  

Type test certification does not involve inspection of the manufacturing facility and the production processes. In some markets type test certification may be sufficient to satisfy the legislative or commercial requirements but in others, particularly where the safety and compliance of mass-produced products is concerned, additional guarantees may be required i.e. full certification. All test reports and certificates are verified by independent Intertek engineers. The ASTA Type Test Certificate issued is sealed and bound to prevent misuse. 

Network of Global ASTA Recognized Laboratories

Shipping heavy bespoke equipment to testing laboratories can be a costly exercise. In order to assist our customers, Intertek has a global network of ASTA recognized laboratories. These recognized laboratories may carry out tests to support the issue of ASTA Certificates and Test Reports in accordance with ASTA’s rules and regulations. Mandated ASTA Observers witness the type tests on behalf of ASTA and the ASTA Observers draft the ASTA reports and certificates which are then sent to the ASTA office for verification and issue. 

Products for which ASTA Type Test Certificates can be issued include: 

Product	Standard
LV Assemblies	IEC 60439-1 / IEC 61439-2
LV Busbar Trunking Systems	IEC 60439-2
LV Distribution Boards	IEC 60439-3
LV Fuses / Fuse holders	IEC 60269 Series
LV Circuit Breakers	IEC 60947-2
LV Fuse Switches	IEC 60947-3
LV Starters / Contactors	IEC 60947-4-1
Miniature Circuit Breakers	IEC 60898
Power Transformers	IEC 60076 Series
HV Circuit Breakers	IEC 62271-100
HV Metal Enclosed Switchgear & Controlgear	IEC 62271-200
Internal Fault (Arc) Tests	IEC 62271-200 Annex A

Copyright :

http://www.intertek.com/

 

Salt mist test

This test serves to demonstrate that under the influence

of a saline atmosphere no damage (corrosion) is caused

to the components of the equipment under test and no

functional affections occur. This test is only performed

on products which are to be installed on the open deck

area.

Cold & Damp Heat test

Cold

This test serves to demonstrate that under the influence

of cold no damage is caused to the equipment under

test and no permanent or temporary malfunctions occur.

5.1 Test procedure

Basis: IEC publication 60068-2-1

– Test A): for products inside the ship

– Test B): for products on the open deck or in

cold areas.

5.2 Test conditions

The functional tests are performed at the rated operational

voltage Ue.

 

Damp heat

This test serves to demonstrate that under the influence

of damp heat no damage is caused to the equipment

under test and no permanent or temporary malfunctions

occur.

7.1 Test procedure

Basis: IEC publication 60068-2-30

– Test Db

7.2 Test conditions

The functional tests are performed at the rated operational

voltage Ue.

Design verification

Design verification is a prerequisite for all assemblies

provided. It is fundamental to ensuring every assembly

meets its defined design requirements. There is flexibility

in the way in which this is achieved within the new standard,

and some new concepts have been introduced, but the

options are defined and where necessary their use is

restricted and a design margin applied.

 

Examples of the limitations and margins applied to verification without type test include;

 All assemblies connected to a supply with a prospective short circuit current in excess of 10kA

 rms or having a cut-off current of 17kA peak must be of a type-tested design or the verification

 must be an interpolation from a reference design. Under no circumstances can the assigned

 short circuit current rating be higher than that of the reference design.

 So as to take account of the air temperature within the enclosure, thermal interactions and

 possible hot spots; components within a circuit that has not been temperature rise tested,

 must be de-rated to 80% of their free air current rating.

 Comparison of the power loss of the components within an assembly with the known heat

 dissipation capability of an enclosure, is restricted to assemblies having a rating of 630A.

 Confirmation of temperature rise performance by calculation is limited to assemblies with a

 rating not exceeding 1600A. Test or interpolation from a tested design must be used to verify

 higher ratings.

EMC Environment

Assemblies can emit and the must be immune to external

 electromagnetic disturbances. IEC defines two categories

 

 a) Environment A - relates to low-voltage non-public or industrial

 networks / locations / installations including highly disturbing sources.

 b) Environment B - relates to low-voltage public networks such as

 domestic commercial and light industrial locations / installations.

 This environment does not cover highly disturbing sources such as

 arc welders.

 The specifier should detail a requirement for either Environment A or B.

 In exceptional applications, for example, some rail applications, it is

 necessary to specify a higher level of immunity.

Rated diversity factor

In reality all circuits within an assembly will not be called upon to carry

their rated current simultaneously and continuously. Diversity is the

 proportion of their rated current each circuit within a group of outgoing

 circuits or all outgoing circuits within the assembly can carry,

 continuously and simultaneously, without the assembly overheating. In

 the absence of any other information in the assembly specification the

 manufacturer will assume the standard diversity factors for the whole

 assembly.

 

Typical RDF

Number of main outgoing circuits	Diversity factor
2 and 3	0.9
4 and 5	0.8
6 to 9 inclusive	0.7
10 and more	0.6
SCHNEIDER ELECTRIC

 

ABB circuit breakers inside LV switchboards

DOWNLOAD :

 

http://www05.abb.com/global/scot/scot209.nsf/veritydisplay/40a2505a059a1f0e48257a700024aa1d/$file/1SDC007103G0202.pdf

Defined IP ratings for different type of environment

Type of assemblies / Type of environment                                         Standards and sub-clause                                            Minimum degree of protection

Switchgear and control gear assembly: enclosed switchboard     IEC 60439-1 sub-clause 2.3.3 Not defined

Assemblies for outdoor installation                                                         IEC 60439-1 sub-clause 7.2.1.3                                    IPX3

Assemblies with protection by total insulation                                    IEC 60439-1 sub-clause 7.4.3.2.2                                IP2XC

Installations in normal environments

Live parts which are not be touched intentionally                             IEC 60364-4 sub-clause 412.2.1                   IPXXB (IP2X)

Live parts which are readily accessible (horizontal top)                   IEC 60364-4 sub-clause 412.2.2                                   IPXXD (IP4X)

Installations in locations containing a bath tube or shower basin

Zones 1 and 2                                                                                                    IEC 60364-7 sub-clause 701.512.2                              IPX4

Zone 3                                                                                                                  IEC 60364-7 sub-clause 701.512.2                              IPX1

Zones 1–2–3 public baths where water jets are used for

cleaning purposes                                                                                           IEC 60364-7 sub-clause 701.512.2                              IPX5

Installations for swimming-pools

Zone 0                                                                                                                  IEC 60364-7 sub-clause 702.512.2                              IPX8

Zone 1                                                                                                                  IEC 60364-7 sub-clause 702.512.2                              IPX5

Zone 2 for indoor locations                                                                          IEC 60364-7 sub-clause 702.512.2                              IPX2

Zone 2 for outdoor location                                                                         IEC 60364-7 sub-clause 702.512.2                              IPX4

Zone 2 where water jets are used for cleaning purposes               IEC 60364-7 sub-clause 702.512.2                              IPX5

Installations for rooms and cabins containing sauna heaters         IEC 60364-7 sub-clause 703.512.2                              IP24

Assemblies for construction sites (ACS)                                                                 IEC 60439-4 sub-clause 7.2.1.1                                    IP44

Heat Dissipation in Electrical Enclosures

The accumulation of heat in an

enclosure is potentially damaging

to electrical and electronic devices.

Overheating can shorten the life

expectancy of costly electrical

components or lead to catastrophic

failure. It is therefore important that

system designers are aware of the

temperature implications of their

designs prior to implementation.

 

Enclosure Temperature Rise The

temperature rise illustrated by the curve in the

graph below is the temperature difference

between the air inside the enclosure and the

air outside the enclosure (or ambient air

temperature).This value is described in the

graph as a function of input power in watts per

square foot. In order to predict the

temperature inside the enclosure, the

temperature rise indicated in the graph must

be added to the ambient temperature where

the enclosure is located.

The enclosure temperature rise is not

dependent on the ambient temperature; rather,

the temperature rise for a given enclosure and

heat input are constant. For example, if the

graph indicates a temperature rise of 30° F, the

interior of the enclosure will be 30° F warmer

than the temperature in the surrounding area.

If the temperature in the surrounding area

reaches a maximum of 100° F then the

enclosure interior will reach a maximum

of 130° F.

Since temperatures in an environment often

vary widely, temperatures within enclosures

will also vary. In general, industrial

environments are warmer in the summer than

in the winter.Therefore, when calculating the

warmest enclosure temperature, use the

maximum ambient temperature that is attained

in a given environment.

 

Enclosure Heat Input For any temperature

rise calculation, the heat generated within the

enclosure must be known.This information

can be obtained from the supplier of the

components mounted in the enclosure. Heat

input values are usually given in watts, but may

also appear in BTU/hour. BTU/hour can be

converted to watts by dividing the value by

3.414 (for example, 341 BTU/hour = 100 watts).

It is not possible to approximate the heat input

for a particular application based on enclosure

size. Heat input varies from application to

application for all enclosure sizes.The system

designer must obtain estimates of heat

input from the information that is available.

Safety factors should be considered if any

uncertainty exists.

 

Enclosure Surface Area The physical size

of the enclosure will be the primary factor in

determining its ability to dissipate heat.

The larger the surface area of the enclosure,

the lower the temperature rise due to the heat

generated within it.

To determine the surface area of an enclosure

in square feet, use the following equation:

Surface Area = 2[(A x B) + (A x C) + (B x C)]÷

144 where the enclosure size is AxBxC

This equation includes all six surfaces of the

enclosure. If any surface is not available for

transferring heat (for example, an enclosure

surface mounted against a wall), it should not

be included in the calculation. It is also

noteworthy that enclosure volume cannot be

used in place of surface area

 

Other Enclosure Materials The graph

below applies to enclosures that are gasketed,

non-ventilated, and constructed of painted

steel. Paint color has little effect on enclosure

temperature rise, except when exposed to sun

(see “Outdoor Applications”). Higher

temperature rises can be expected with

aluminum and stainless steel enclosures due to

the poor radiant heat transfer effects of their

metallic finishes.To find the temperature rise of

these enclosures, multiply the results found in

the graph by 1.5. Non-metallic enclosures have

similar heat transfer characteristics to those

constructed of painted steel, so the graph can

be used directly despite the difference in

material.

What is IP69K?

What is IP69K?

 

The IP69K rating is for applications where high

pressure and high temperature washdown is used to

sanitize equipment.

The IP69K test specification was initially developed

for road vehicles, especially those that need regular

intensive cleaning (dump trucks, cement mixers, etc),

but has been widely adopted in the Food & Beverage

industries as a test of products to withstand sanitary

washdown.

 

What does IP69K mean?

 

In the IEC 60529 rating system, IP6 refers to the product’s ability to resist

ingress of dust. The 69K refers to the product’s ability to resist ingress of

high temperature (Steam) / high pressure water.

 

How is the product tested?*

 

• Products rated to IP69K must be able to withstand high-pressure and

steam cleaning.

• The test specifies a spray nozzle that is fed with 80 °C water at 80–100

bar (~1160-1450) and a flow rate of 14–16 L/min.

• The nozzle is held 10–15 cm from the tested device at angles of 0°, 30°,

60° and 90° for 30 seconds each.

• The test device sits on a turntable that rotates once every 12 seconds