YB2 Series 6-Pole Explosion-Proof Motor
Six-pole flameproof squirrel-cage induction motor certified Ex d IIB T4 for Zone 1 and Zone 2 hazardous areas, running at approximately 960 rpm on 380 V 50 Hz. High shaft torque at moderate speed makes the 6-pole YB2 the preferred specification for classified-area slow-speed mixers, low-head fans, and applications where a single-stage reduction between motor and load is required within the hazardous zone boundary.
Zone 1 / Zone 2
Speed: ~960 rpm (6P)
Power: 1.1 – 132 kW
Protection: IP55
Insulation: Class F
Slow-Speed Flameproof Motor for Classified Mixer and Fan Drives
The 6-pole YB2 operates at approximately 960 rpm, producing 50% more shaft torque than a 4-pole motor of the same power rating and frame size. In hazardous areas, this torque advantage has a specific practical benefit: it allows the motor to be coupled directly to the driven equipment through a single-stage reduction, eliminating a gearbox unit from inside the classified zone. Each additional mechanical component inside a Zone 1 boundary requires its own maintenance inspection and represents another potential ignition source or fluid leak; removing the gearbox entirely simplifies the safety case for the complete drive assembly.
The flameproof enclosure design and flame path machining follow the same IEC 60079-1 specifications as all other YB2 pole variants. The 6-pole frame runs at a lower surface temperature at full load than a 4-pole motor of the same frame at the same power, because the lower shaft speed reduces windage losses and mechanical friction in the bearings and shaft seal, both of which generate surface heat. This additional thermal margin gives the 6-pole motor a more comfortable compliance band below the T4 surface temperature limit of 135 °C.
Frame sizes cover 90S through 315M (1.1 kW to 132 kW). All units carry IP55 protection, Class F insulation with Class B temperature-rise limits, and CE plus Ex marking. Cast-iron construction throughout all frame sizes provides the wall thickness required for certified flame path geometry.
Browse the complete Ex motor range on the Explosion-Proof Motors page, or compare matched non-hazardous motors in the Three-Phase Induction Motors section.
YB2 6-Pole Model Specifications — Ex d IIB T4
All models: 6-pole, ~960 rpm, 380 V 50 Hz, IP55, Class F insulation, Ex d IIB T4, Zone 1 and Zone 2.
| Model | Frame | kW | Full-Load A | rpm | η % | cosφ | Tst/Tn | Ist/In | kg |
|---|---|---|---|---|---|---|---|---|---|
| YB2-90S-6 | 90S | 1.1 | 3.54 | 910 | 68.0 | 0.70 | 2.0 | 5.5 | 32 |
| YB2-90L-6 | 90L | 1.5 | 4.60 | 920 | 70.0 | 0.71 | 2.0 | 5.5 | 40 |
| YB2-100L-6 | 100L | 2.2 | 6.28 | 930 | 73.0 | 0.72 | 2.0 | 5.5 | 52 |
| YB2-112M-6 | 112M | 3.0 | 8.28 | 940 | 75.5 | 0.73 | 2.0 | 6.0 | 74 |
| YB2-132S-6 | 132S | 4.0 | 10.78 | 945 | 77.0 | 0.74 | 2.0 | 6.0 | 96 |
| YB2-132M1-6 | 132M | 5.5 | 14.36 | 948 | 79.5 | 0.74 | 2.0 | 6.0 | 124 |
| YB2-132M2-6 | 132M | 7.5 | 19.10 | 950 | 81.0 | 0.75 | 2.0 | 6.0 | 142 |
| YB2-160M-6 | 160M | 11 | 27.00 | 955 | 83.5 | 0.76 | 2.0 | 6.5 | 175 |
| YB2-160L-6 | 160L | 15 | 36.50 | 958 | 85.0 | 0.77 | 2.0 | 6.5 | 208 |
| YB2-180L-6 | 180L | 18.5 | 44.50 | 960 | 86.5 | 0.78 | 2.0 | 6.5 | 258 |
| YB2-200L1-6 | 200L | 22 | 52.60 | 962 | 87.5 | 0.79 | 2.0 | 6.5 | 322 |
| YB2-200L2-6 | 200L | 30 | 70.80 | 964 | 88.5 | 0.80 | 1.8 | 6.5 | 368 |
| YB2-225M-6 | 225M | 37 | 86.50 | 966 | 89.5 | 0.80 | 1.8 | 6.5 | 450 |
| YB2-250M-6 | 250M | 55 | 126.00 | 968 | 90.5 | 0.81 | 1.8 | 6.5 | 575 |
| YB2-280S-6 | 280S | 75 | 170.00 | 970 | 91.5 | 0.82 | 1.8 | 6.5 | 728 |
| YB2-315S-6 | 315S | 90 | 202.00 | 972 | 92.0 | 0.82 | 1.8 | 6.5 | 895 |
| YB2-315M-6 | 315M | 132 | 294.00 | 974 | 92.5 | 0.83 | 1.8 | 6.5 | 1100 |
Operating Conditions
| Ambient temperature | −20 °C to +40 °C |
| Altitude | ≤ 1000 m ASL |
| Supply voltage | 380 V ± 5% |
| Frequency | 50 Hz ± 1% |
| Mounting | IMB3 / IMB5 / IMB35 |
| Protection | IP55 |
| Insulation class | Class F |
| Temperature rise | Class B limit |
| Max surface temp | 135 °C (T4) |
Hazardous Area Certification
| Protection method | Ex d (flameproof) |
| Gas group | IIB |
| Temperature class | T4 (135 °C max) |
| Zone suitability | Zone 1, Zone 2 |
| Ex standard | IEC 60079-1 |
| Motor standard | IEC 60034 |
| Quality management | ISO 9001 |
| Marking | CE / Ex |
Typical Applications for YB2 6-Pole Explosion-Proof Motors
Classified Zone Agitators
Side-entry and top-entry agitators on storage tanks and reaction vessels in Zone 1 classified areas use 6-pole Ex d motors for their high torque at low speed, avoiding the need for a gearbox inside the hazardous zone and reducing the total component count requiring Ex certification.
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Large-Diameter Hazardous Fans
Large-diameter axial and centrifugal fans for classified area ventilation at 960 rpm use the 6-pole YB2 to achieve the fan tip speed required for efficient airflow without belt or gear drive, simplifying the installation inside the classified zone boundary.
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Mining Zone 1 Drives
Coal preparation plant conveyors and underground mine auxiliary equipment in Zone 1 methane-classified areas use 6-pole Ex d IIB motors. IIB certification covers methane (Group IIA by upward compatibility) with margin, satisfying the typical mine electrical safety specification.
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Paint Booth Exhaust
Exhaust plenum fan motors in automotive paint booths classified Zone 1 for solvent vapours use 6-pole Ex d IIB T4 motors to drive large-diameter low-pressure fans at 960 rpm, providing the required air change rate without excessive noise from high blade tip speeds.
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Flare Gas Compressors
Low-pressure flare gas recovery screw compressors at refineries and chemical plants operate in Zone 1 areas and require Ex d IIB motors at moderate speed. The 6-pole motor at 960 rpm is commonly used with a belt drive to match the compressor rotor speed in this duty.
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Ballast Water Pumps
Ballast water pump motors in the classified cargo hold areas of chemical tankers and LNG carriers must carry Ex d certification. The 6-pole motor provides the torque needed for large-bore low-speed ballast pumps without the space penalty of a gearbox between motor and pump casing.
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Thermal Advantage of Lower Speed in Ex d Motor Design
T4 Compliance Margin
The T4 temperature class limits the maximum surface temperature of the motor to 135 °C under any operating condition. A 6-pole motor at 960 rpm generates less windage heat and lower bearing friction losses than a 4-pole motor at 1460 rpm or a 2-pole motor at 2900 rpm at the same rated power. This lower mechanical heat generation means the 6-pole motor has a wider margin below the 135 °C T4 ceiling at full rated load in maximum ambient temperature, making T4 compliance easier to maintain under overload conditions and in ambient temperatures approaching 40 °C.
Shaft Seal Integrity at Lower Speed
The flameproof shaft seals at both ends of the motor are critical flame path elements. Seal lip wear rate increases with shaft surface speed; at 960 rpm, the shaft surface speed through the seal contact zone is approximately 34% of the speed at 2900 rpm. Reduced wear means the certified seal gap dimension is maintained for longer, extending the period between mandatory seal inspections and replacements. This is a meaningful maintenance cost saving in hazardous areas where even seal inspection requires a hot-work permit and area isolation in Zone 1.
Noise and Vibration in Classified Areas
Ex d motors operating in classified areas are often located adjacent to gas detectors, pressure relief valves, and instrumentation that is sensitive to vibration. The 6-pole motor at 960 rpm produces substantially lower vibration than a 4-pole or 2-pole motor at the same power because both the unbalance force and the aerodynamic fan noise scale with speed. Reduced vibration lowers the transmitted force to flanges and pipework connected to motor-driven pumps, reducing the risk of fatigue failure at pipe joints — which would themselves generate an unplanned flammable release.
Frequently Asked Questions — YB2 Series 6-Pole Explosion-Proof Motor
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Informazioni aggiuntive
| Editor | Cxm |
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