Suppliers, Distributors, and Exporters of Flame Proof Motors

Flame proof motors are equipment which can perform safely in the following conditions:

Hazardous Area

An installation where inflammable products are continually handled, processed or stored requires special care to ensure the maintenance of property and the personnel safety.

Based on their characteristics, electric equipment can become ignition sources causing sparks, when opening or closing contacts or due to overheating of any component, caused intentionally or originated by fault currents.

Explosive Atmosphere

An atmosphere is considered explosive when the proportion of gas, vapour, dust, fibres, or flyings is such that after sparking caused by short-circuit or overheating of one component causes an ignition and explosion. Three elements are required for an explosion to occur:

Fuel + oxygen + ignition = explosion

Classification of Hazardous Areas

According to IEC/IS Standards, hazardous areas are classified as follows:

Zone 0

Area in which explosive atmosphere is present continuously, or for long periods of frequently. For example, inside a fuel tank the explosive atmosphere is always present.

Zone 1

Area in which an explosive gas atmosphere is likely to occur in normal operation occasionally. The explosive atmosphere is frequently present.

Zone 2

Area in which an explosive gas atmosphere is not likely to occur in normal operation, but if it does occur, will persist for a short period only. This conditions associated with abnormal operation of equipment and process, losses or negligent use. The explosive atmosphere may accidentally be present.

Protection by Enclosure

• Sturdy housing which prevents an internal explosion from spreading to the outside and resists the explosion pressure.
• Robust bearing shields and caps bolted to the frame in such a manner that the gaps remain unaffected in the event of an internal explosion.
• Screen on air intake with a mesh size not exceeding 8 mm.
• External earth terminals.
• Protective earth conductor terminal in the terminal box.
• (Ex) d mark on the motor.
• CMRI certificate no., CCE & DGFASLI certificate no. & ISI licence mark on the name plate.
• PESO Approval mark on the name plate
• Special varnishing and painting treatment to resist highly corrosive atmosphere.

Design of Enclosure

The frame, and shields, terminal boxes and bearing covers of all motors are made of grey cast iron. The motors are so designed that the frame temperature will remain below the ignition temperature of the gas-air mixture involved.

Insulation

All cast iron parts forming the flame proof enclosures are subject to hydraulic pressure test, after final machining as per IS:2148 – 1982.

Cooling

All motors have bi-directional, cast iron or fabricated fans.

Terminal Box

As a standard terminal box is on top for all Flame Proof Motors.

Cable Entries

Motors for mining application (Gas Group I) are provided with cable entries with compound filling sealing boxes suitable for paper insulated lead covered double wired armoured (PILCDWA) PVC cables. Cable entries with flameproof cable glands can also be provided to suit PVC armoured cables.

Motors in all frame sizes can be supplied with termination suitable for plug & socket arrangement, against enquiry.

A cable sealing box is mandatory in the following cases.

a. All motors for use for Gas Group. I & Oil Mines.

b. When cable size is more than 1 inch. for Gas Group. IIA & IIB.

Temperature Classes

The maximum temperature on the outer and/or inner surface of an electric equipment must always be lower than the ignition temperature of the gas or steam. Gases can be classified for temperature classes based on their ignition temperature, where the maximum surface temperature of the corresponding class must be lower than the corresponding temperature of the gases.

As specified according to IEC /IS following are the temperature classes:

TYPE Ex d – FLAMEPROOF (according to IEC 60079-1)

It is a type of protection where the parts that may flame an explosive atmosphere are closed into enclosures which are capable to withstand a pressure during an internal explosion of an explosive mixture and it avoids such explosion to go out from this enclosure to an external explosive atmosphere.

The motor surfaces do not need to be totally enclosed to avoid flame propagation. The minimum opening required to avoid passage of flames depends on the gas or vapour that is present. Therefore, there will always be flame passages through the motor enclosure. The safety level on an explosion proof motor is on the fact that it must ensure that all flame passages never exceed the standardized dimensions and that the motor is physically suitable to withstand an internal explosion without transmitting it to the external environment.

Ex d protection will not allow that an internal explosion propagates to the external environment. To ensure safety to the system, Motors are provided with control of the openings and the finishing of joints once these are responsible for the volume of gases exchanged between inside and outside of the motor. Flame propagation between motor interior and external atmosphere is guaranteed by constructive joints and gaps. Internal pressure that can result of an explosion in the interior of the motor is guaranteed by the enclosure resistance (frame, endshields, internal bearing covers, terminal boxes and some adaptors).

Increased Safety Equipment Type Ex e (according to IEC 60079-1 and IEC 60079-7)

This electrical equipment, under normal operating conditions, does not generate arcs, sparks or sufficient heat to cause ignition of the explosive atmosphere for which it was designed.

Time t_E - time taken for an a.c. rotor or stator winding, when carrying the initial starting current IA, to be heated up to the limiting temperature from the temperature reached in rated service at the maximum ambient temperature.

TYPE Ex nA – NON SPARKING MOTORS (according to IEC 60079-15)

This type of protection is applied to electric equipment which do not cause ignition of an explosive atmosphere under normal operating conditions and in certain abnormal conditions.

The design and constructive principles for these apparatus must guarantee that in normal operation a spark or arc is prevented from causing ignition in a surrounding explosive atmosphere and that the internal and external surfaces temperatures do not overpass the maximum surface temperature certified.

Explosion-Proof Equipment

It is a type of protection where the parts that may ignite an explosive atmosphere are confined within enclosures that can withstand the pressure caused by an internal explosion of an explosive atmosphere and prevents the transmission of the explosion to an explosive atmosphere.

• Oil & Gas Industries
• Chemical Plants
• Industries with Hazardous Environments

Flame Proof Motors

Contact us for more information on Flame Proof Motors or to discuss your requirements. Enquiries are solicited for India, UAE and Africa on following Email id web@aakashpower.com