machines for hazardous areas

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Machines for hazardous areasExp & Exd

BU Machines UpdateFebruary 24 G. Pedrinoni

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According to European Directives 94/9/EC (ATEX), IEC 60079-10, EN 60079-10 and NEC 505, hazardous environments are classified, relating to the presence probability of flammable substances, in ZONES:

Zone “0” ( Gas presence > 1000 Zone “0” ( Gas presence > 1000 hours/year)hours/year)

Area where an explosive gas mixture is present continuously, for long period or frequently

(Zone “20” for dust) Zone “1” ( Gas presence 10 - 1000 Zone “1” ( Gas presence 10 - 1000 hours/year)hours/year)

Area where an explosive gas mixture is likely to occur under normal operations(Zone “21” for dust)

Zone “2” ( Gas presence < 10 hours/year)Zone “2” ( Gas presence < 10 hours/year)Area where an explosive gas

mixture is unlikely to occur (or occur only under abnormal conditions)

(Zone “22” for dust)

Hazardous environments - Group II

PRESENCE DURING NORMAL OPERATIONS

PRESENCE JUST IN CASE OF FAILURE OR ABNORMAL OPERATIONS

CONTINUOUS PRESENCE

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Gas and Vapor Subdivisions

SubdivisionMax ExperimentalSafe Gap (MESG)

IEC 60079-10Products

A > 0. 9 mm~120 gases and Vapors :ethane-propane-butane

benzene-methanepetroleumdiesel oil-ethanethiol

B 0.55 mm - 0.9 mm~30 gases and vapors :ethylene-dimethyl ether

coke oven gas

C < 0.5 mm3 gases

hydrogen H2 - acetylene C2H2 carbon disulphide CS2

Gases are classified by groups based on the maximum gap that still prevents any transmission of an explosion in 10 tests made, the conditions specified in the standards IEC and EN.

Three groups have been defined: A - B - C according to the value of Maximum Experimental Safety Gap (MESG).

25 mm

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Temperature Classes and Gas Groups

Flammable substances are divided into six Temperature Classes according to their Auto Ignition Temperature (AIT):

Air mixtures, gas and vapors are grouped in function of the highest explosion pressure, in two groups and three subgroups

Group II (other than mines)IIA Propane

IIB Ethylene

IIC Acetylene, Hydrogen

Hazardous environments

Group I (mines)

AIT >450 °C 450...300°C 250° C 190° C 90° C

Temp. of the 450 °C 300° C 200° C 135°C 85°Cnearest class

Temp. class

Compond or Ammonia, Ethylen, Petroleum Ethyl Ether Ethyl Nitrate

GAS Hydrogen Acetylene

T1 T2 T3 T4 T6T1 T2 T3 T4 T6

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Hazardous environments

Based on these values the appropriate temperature class will be determined for an equipment installed safely in the area containing a combustable substance which does not exceed the auto-ignition temperature of the substance. This temperature class is mostly not exceeding 80% of the AIT, and in many industries may be even lower to provide a bigger safety margin.

Classification of gases and vapours in explosion groups and temperature classes

T1 T2 T3 T4 T5 T6

I Methane -

IIA AcetoneEthaneEthylacetateAmmoniaBenzolAcetic AcidCarbon monoxideMethanolPropaneToluene

EthylalcoholI-amyl acetateN-buthaneN-btylalcohol

PetrolDiesel fuelAviation fuelHeathing oilN-hexane

Acetaldehyde -

IIB Town gas(lamp gas)

Ethylen -

IIC Hydrogen Acethylene - Carbon disulphide

Comparison between Division and Class Grouping

Typical Gas

Dision System

NEC 505

Zone System

EN & IEC

Acetylene

Group A

Hydrogen

Group B

Group IIC

Ethylene

Group C

Group IIB

Propane

Group D

Group IIA

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Apparatus groups Group IGroup I - Mines susceptible to firedamps - Mines susceptible to firedamps Group IIGroup II - Other places - Other places

Gas groups ((needed only for Ex d and Ex ineeded only for Ex d and Ex i))

IIAIIA (e.g. Propane) (e.g. Propane) IIBIIB (e.g. Ethylene) (e.g. Ethylene) IICIIC (e.g. Acetylene and Hydrogen) (e.g. Acetylene and Hydrogen)

Zones Zone 0Zone 0

- continuously- continuously Zone 1Zone 1

- occasionally- occasionally Zone 2Zone 2

- in abnormal conditions- in abnormal conditions

Temperature classesT1 T2 T3 T4 T5 T6

450 C 300 C 200 C 135 C 100 C 85 C

IEC and EN standardsNot suitable for motors

Ex dEEx dEx eEEx eEx pEEx p

Ex nAEEx nAEx dEEx dEx eEEx eEx pEEx p

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Marking according to IEC

Ex – Explosion protected apparatus

”d”, ”e”, ”p”, ”nA” – Type of protection

IIA, IIB, IIC – Gas group Used only wiyh protection types ”d” and

”i”

T3, T4, T5, T6 – Temperature class

Ex d IIC T4

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NEMA / NECNEMA / NEC

CSA / CEC CodeCSA / CEC Code

JSIJSI

ENEN

National and International Standards

AS/NZSAS/NZS

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Testing of Samples (Type Test)

Initial Assessment of Manufacturer’s Quality System (factory audit)

On-going Surveillance (factory audits)

Core elements of IECExScheme Certification

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Connection facilities and earthing orbonding conductors Requirements of connection facilities are specified

in the std. All surfaces, which can charge electrically, shall

be earthed or equipotential bonded

General Requirements (IEC 60079-0 and EN50014)

Enclosures shall be designed that a electrostatic charges are avoided

These rules are valid for all protection modes

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General Requirements (IEC 60079-0 and EN50014)

Cable and conduit entries Cable and conduit entries shall be constructed and fixed so that they do not alter the specific characteristics of the type of

protection. They are already Ex-certified!

Ventilation openings for external fan IP20 on the air inlet side IP10 on the air outlet side

Clearance and material of external fan and fan hood Clearance between fan and fan hood must be at least 1% of the diameter of fan (min.1mm,max.5mm) The insulation resistance of the fans, fan hood or ventilation screen shall not exceed 1G if v > 50m/s The fans, fan hood or ventilation screen shall not contain by mass

more than 6% of magnesium if they are realized in alloy metals

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What does it mean Pressurized enclosure ?

Parts which could ignite an explosive gas mixture are housed in an enclosure which is flushed and pressurized by a

protective gas, e.g. clean air.

Outlet inert gas

Inlet

inert gas

Pressurized Motors – EEx p

po

p > po

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Pressurised motors EEx p(e) II T1-T4

Induction motors Output up to 18 MW Frame sizes: 315 - 1120

Category 2 EquipmentZone 1Standards EN 50016

Synchronous motors Output: up to 55 MW Frame sizes: IEC 710 - 1250

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Cooling type possible for Exp machines

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Pressurization System’s Components

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EnclosureEnclosure Ingress protection shall

be at least IP40 Shall withstand a pressure

equal to 1.5 times the maximum over-pressure

Temperature limits Temperature limits Temperature of the external surface shall not be over temperature

class limit during any operation Temperature of internal point shall not be over temperature class

limit during the normal service

Over-pressure and protective gasOver-pressure and protective gas The over-pressure shall be all the time at least 50 Pa The protective gas can be clean pressurized air, supplied from non-

hazardous area

Ex p / EEx p standard Ex p / EEx p standard (IEC60079-2 / EN60079-2)(IEC60079-2 / EN60079-2)

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PurgingPurging The basic idea is to remove an explosive gas mixtures before

starting of the motor Duration of purging shall be tested, so that concentration of

flammable gas after purging shall not exceed 25 % of the LEL (Lower Explosion Limit)

Accessories and certificationAccessories and certification Internal accessories must be Ex-certified for zone 1 area, if they

can be switch on before motor is purged (e.g. space heater). Other internal accessories can be non-certified.

External accessories shall be always Ex-certified for zone 1 area

Third party certificate is always required

Ex p / EEx p standard Ex p / EEx p standard (IEC60079-2 / EN60079-2)(IEC60079-2 / EN60079-2)

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What does mean Flameproof enclosure ?

The enclosure is designed in such a way that an explosion inside the motor will not cause any permanent deformation and will prevent

the flame propagation outside

seals and labyrinths

strong housing

(frame and shields)

Ex d or EEx d standards (IEC 60079-1 / EN50018)

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Flameproof motors EEx d(e) IIB/IIC T4-T6

Low voltage motors Output: 0.55 - 630 kW Frame sizes: IEC 80 - 400 Larger frame sizes and higher

outputs also available

Category 2 EquipmentZone 1Standards EN 50018/IEC 60079-1

High voltage motors Output: 160 - 4500 kW Frame sizes: IEC 355 - 710

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What is Flameproof enclosureWhat is Flameproof enclosure

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Cooling type possible for Exd machines IC411 IC511

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Ex d machines are designed to guarantee the protection x d machines are designed to guarantee the protection in normal operation, in start and in fault conditions. in normal operation, in start and in fault conditions.

1. In case of an explosion inside the motor, the explosion is not transmitted outside the enclosure

2. The maximum surface temperature outside the motor lower than the temperature class

3. No sparks outside the enclosure

4. Hot gases can't pass to the outside, or when occur, they have to be cool enough to be at a temperature which is below the temperature class limit.

Ex d / EEx d standard Ex d / EEx d standard (IEC60079-1 / EN60079-1)(IEC60079-1 / EN60079-1)

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Temperature limits Temperature limits Temperature of the external surface shall not be over the

temperature class limit for which the motor is certifiedEnclosures designEnclosures design Insulation resistance of the enclosure does not exceed

1G (EN/IEC). All electrostatic charges are avoided. All surfaces, which

can charge electrically, shall be earthed or equipotential bonded .(Requirements of connection facilities are specified in the std.)

Enclosures are designed and tested to withstand the pressure in case of an internal explosion.


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Stator and Rotor designStator and Rotor design The stator and rotor design is the same as standard

machines. No special limitation for rotor temperature

Degree of mechanical protection Degree of mechanical protection IP54 where there are bare live parts (terminal boxes) IP44 where there are insulated live parts (frame)

Cable and conduit entriesCable and conduit entries Cable and conduit entries shall be constructed and

fixed so that they do not alter the specific characteristics of the type of protection.


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Clearance and material of external fan and fan hoodClearance and material of external fan and fan hood The prescription of the General Rules about the clearance, insulation

resistance of the materials and the material characteristics must be followed.

Fan is always Non-Sparking

Accessories and certificationAccessories and certification Internal accessories can be non-certified. External accessories shall be always certified. Third party certificate is required for motor series (prototype

tested only).

VSD ApplicationVSD ApplicationNo need to carry out the system test for VSD application


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FAQ

Different way of protecting the motor... Which type of protection is better for Main Terminal Box? Exe or Exd

Sleeve bearings are not allowed by international standards. for gas group IIC

Why ABB cannot deliver motors with sleeve bearings for gas group IIC?

International standards do not set any limit for tE time for Exp and Exd machines

Is the tE time relevant for pressurized or flameproof machines?

The motor shall be “de-rated” to fulfill max. 80K temperature rise. Major attention shall be paid to the bearings

What happens if the ambient temperature is above 40C

Typically ca. 10 min for TEFC (IC411) and ca. 30min for large TEAAC (IC611) and TEWAC (IC81W) motors.

Yes, the purging air can be supplied from instrument air ntework

What is typical purging time for Ex p motor before starting. And, can the purging air be the standard instrument air

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Apparatus groups Group IGroup I - Mines susceptible to firedamps - Mines susceptible to firedamps Group IIGroup II - Other places - Other places

Gas groups ((needed only for Ex d and Ex ineeded only for Ex d and Ex i))

IIAIIA (e.g. Propane) (e.g. Propane) IIBIIB (e.g. Ethylene) (e.g. Ethylene) IICIIC (e.g. Acetylene and Hydrogen) (e.g. Acetylene and Hydrogen)

Zones Zone 0Zone 0

- continuously- continuously Zone 1Zone 1

- occasionally- occasionally Zone 2Zone 2

- in abnormal conditions- in abnormal conditions

Temperature classesT1 T2 T3 T4 T5 T6

450 C 300 C 200 C 135 C 100 C 85 C

IEC and EN standardsNot suitable for motors



Ex nAEEx nA

machines for hazardous areas

Engineering