YB2 Series 4-Pole Explosion-Proof Motor

Four-pole flameproof squirrel-cage induction motor certified Ex d IIB T4 for Zone 1 and Zone 2 hazardous areas. Running at approximately 1460 rpm on 380 V 50 Hz, the 4-pole YB2 is the most widely specified explosion-proof motor across the full range — covering the majority of hazardous area pump, compressor, agitator, and conveyor drives where moderate speed and high torque are both required.

Ex d IIB T4 Certified
Zone 1 / Zone 2
Speed: ~1460 rpm (4P)
Power: 0.55 – 200 kW
Protection: IP55
Insulation: Class F

Categoria: Explosion-Proof Motors

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Ex d Flameproof

Group IIB T4

4-Pole 1460 rpm

IP55 Protection

IEC 60079-1

ISO 9001 Certified

YB2 Series 4-Pole Explosion-Proof Motor Ex d IIB T4 Korea Ever-Power

YB2 Motor IEC Mounting Methods IMB3 IMB5 IMB35

The Most Widely Used Explosion-Proof Motor in the YB2 Range

The 4-pole YB2 is the default specification for hazardous area motor installations. At 1460 rpm, it matches the operating speed of the largest range of centrifugal pump impellers, compressor stages, and fan rotors designed for direct coupling to 50 Hz induction motors. This eliminates the need for belt or chain drives between motor and driven equipment, which would themselves present additional potential ignition sources in a classified area and require their own hazardous-area safety assessment.

The flameproof enclosure design follows IEC 60079-1 exactly as for the 2-pole variant, with all flame path joints machined to certified dimensions. The 4-pole winding produces twice the shaft torque of the 2-pole motor at the same power rating, giving the 4-pole motor a significant advantage in direct-coupled agitator and mixer applications where high starting torque under viscous load is required alongside the moderate operating speed.

The power range extends from 0.55 kW (frame 71) through 200 kW (frame 315M), the widest range in the YB2 series. All units carry IP55 protection, Class F insulation, and both CE and Ex marks. The terminal box accommodates flameproof cable glands for the cable sizes appropriate to each frame, with sufficient internal volume for safe termination of armoured cables without deforming the cable gland assembly.

View the full explosion-proof range on the Explosion-Proof Motors page, or compare with the Three-Phase Induction Motors for non-hazardous area equivalents.

YB2 4-Pole Model Specifications — Ex d IIB T4

All models: 4-pole, ~1460 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
YB2-71M-4	71M	0.55	1.68	1380	69.5	0.75	2.2	5.5	14
YB2-80M1-4	80M	0.75	2.22	1390	72.5	0.76	2.2	6.0	22
YB2-80M2-4	80M	1.1	3.14	1400	75.5	0.77	2.2	6.0	24
YB2-90S-4	90S	1.5	4.14	1410	77.5	0.78	2.2	6.0	30
YB2-90L-4	90L	2.2	5.78	1420	80.0	0.79	2.2	6.5	38
YB2-100L1-4	100L	3.0	7.50	1430	82.0	0.80	2.2	6.5	48
YB2-100L2-4	100L	4.0	9.80	1440	83.5	0.80	2.2	6.5	54
YB2-112M-4	112M	5.5	12.80	1445	85.0	0.82	2.2	7.0	72
YB2-132S-4	132S	7.5	16.90	1448	86.5	0.83	2.2	7.0	92
YB2-132M-4	132M	11	24.20	1450	87.5	0.83	2.2	7.0	120
YB2-160M-4	160M	15	32.00	1455	88.5	0.84	2.0	7.0	160
YB2-160L-4	160L	18.5	38.80	1458	89.5	0.84	2.0	7.0	188
YB2-180M-4	180M	22	45.40	1460	90.5	0.85	2.0	7.0	235
YB2-180L-4	180L	30	60.50	1460	91.0	0.86	2.0	7.0	282
YB2-200L-4	200L	37	73.50	1462	92.0	0.86	2.0	7.0	345
YB2-225S-4	225S	45	88.00	1464	92.5	0.87	2.0	7.0	410
YB2-225M-4	225M	55	106.00	1465	93.0	0.87	2.0	7.0	480
YB2-250M-4	250M	75	143.00	1468	93.5	0.88	2.0	7.0	605
YB2-280S-4	280S	90	170.00	1470	94.0	0.88	2.0	7.0	720
YB2-315S-4	315S	132	248.00	1472	94.5	0.89	2.0	7.0	950
YB2-315M-4	315M	200	372.00	1475	95.0	0.89	2.0	7.0	1180

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 4-Pole Explosion-Proof Motors

YB2 4-Pole Motor Hazardous Area Pump Application

API Process Pumps

API 610 and API 676 process pumps for refinery and chemical plant duties are designed for direct coupling to 4-pole motors at 1460 rpm. The YB2-4 is the standard motor specification for these pumps in classified Zone 1 process areas across the majority of oil and gas engineering standards.

YB2 4-Pole Motor Hazardous Compressor Application

Gas Compressor Drives

Screw and reciprocating compressors in natural gas gathering stations, LPG terminals, and biogas upgrading plants use 4-pole Ex d motors as the primary drive because most compressor designs are optimised for input speeds in the 1200 to 1500 rpm range matching the 4-pole motor.

YB2 4-Pole Motor Pharmaceutical Hazardous Application

Pharmaceutical Reactors

Top-entry agitators on classified pharmaceutical synthesis reactors use 4-pole Ex d motors for the combination of moderate impeller speed, high starting torque for viscous batches, and Ex d flameproof protection required by ATEX zone classification of solvent-handling reaction areas.

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Zone 1 Conveyor Drives

Screw conveyors and belt conveyors inside chemical storage warehouses, flour mills, and grain silos classified as Zone 1 or Zone 2 for combustible dust and flammable vapour use 4-pole Ex d IIB motors as the standard drive motor throughout the classified area boundary.

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Offshore Platform Equipment

Seawater lift pumps, firewater pumps, and injection water pumps on oil and gas production platforms operate in Zone 2 classified areas and require Ex d IIB T4 motors that also meet offshore environmental requirements for salt air, vibration, and corrosion resistance.

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Solvent Recovery Systems

Distillation column reboiler pumps, reflux pumps, and solvent condensate pumps in solvent recovery and recycling plants handle flammable liquids at elevated temperatures, requiring Ex d IIB T4 motors throughout the classified area surrounding each distillation column.

Why the 4-Pole Configuration Dominates Hazardous Area Motor Specifications

Equipment Speed Compatibility

The majority of centrifugal pumps, fans, compressors, and agitators used in the process industries are designed with specific-speed characteristics optimised for direct coupling to 4-pole motors at 1440 to 1480 rpm. Pump hydraulic design, impeller geometry, and shaft seal assembly dimensions are all coordinated around this speed in IEC-aligned markets. Specifying a 4-pole Ex d motor therefore eliminates the need for a belt or gear drive between motor and driven equipment, which would itself require hazardous area assessment and add maintenance complexity inside the classified zone.

Torque Advantage Over 2-Pole for Agitators

A 4-pole motor produces twice the shaft torque of a 2-pole motor at the same power rating, because torque equals power divided by angular velocity. For top-entry agitators starting under full viscous load, this additional torque margin allows reliable cold-batch starting without star-delta starting or soft-starter intervention. In classified areas, minimising auxiliary starting equipment inside the zone boundary reduces both the total number of certified components required and the inspection load during periodic maintenance shutdowns.

Thermal Management at IP55

Ex d motors operate at IP55 as standard, which means the cooling fin surface must transfer all winding heat to the ambient air without any ingress of external air through the motor enclosure. The 4-pole motor at 1460 rpm delivers full rated cooling fan airflow and fin surface velocity, maintaining the motor within T4 surface temperature limits at full rated load. This self-contained cooling arrangement is essential in hazardous areas where external forced cooling blowers would require their own Ex certification and separate power supply.

Rotor Production Line

Precision Flame-Path Machining

QC and Certification Inspection

Ex and ISO Certifications

Frequently Asked Questions — YB2 Series 4-Pole Explosion-Proof Motor

Why is the 4-pole YB2 power range wider than the 2-pole range?

The 4-pole range starts at 0.55 kW (frame 71) versus 0.75 kW (frame 80) for the 2-pole, and extends to 200 kW (frame 315M) versus 132 kW for the 2-pole. At the small end, the 4-pole winding is physically easier to wind in small frames at 1460 rpm than a 2-pole winding at 2900 rpm, because the longer conductor in the 4-pole winding improves slot-fill efficiency at small wire gauges. At the large end, the higher torque demand per unit power of large agitator and conveyor applications favours 4-pole motors over 2-pole, so market demand for large-frame 4-pole Ex d motors is significantly higher.

What inspection and maintenance regime applies to Ex d motors in service?

IEC 60079-17 defines the inspection regime for electrical installations in hazardous areas. Initial inspection (before first energisation) verifies correct installation, cable gland type and tightness, stopping plugs in unused entries, and legibility of Ex markings. Periodic inspection (typically annual for Zone 1, every 3 years for Zone 2) checks flame path joint condition and gap dimensions, surface temperature marking legibility, and absence of unauthorised modifications. Insulation resistance testing should be performed annually. All inspection records must be retained as part of the installation safety documentation. Korea Ever-Power can provide the required flame path dimensions and surface finish specifications for inspection reference.

Can I install additional temperature monitoring devices on the YB2-4?

PTC thermistors can be factory-fitted in the stator winding as a standard option, with leads routed through the flame-path gland in the terminal box cover. Adding any sensor leads through the terminal box after factory build requires use of a certified Ex d cable gland and an appropriate stopping plug for any unused sensor entries. Adding accessories to the outside of the Ex d enclosure (mounting brackets, terminal box adaptors) must not impair the flame path integrity of any joint. Any modification must be assessed against the original Ex certification and may require re-submission to the certification body if the modification is not covered by the existing certificate.

Is the YB2-4 available in dual-voltage winding (for 380V/660V or 230V/400V)?

Yes. Korea Ever-Power can supply the YB2-4 with dual-voltage windings for markets where the supply voltage is different from the standard 380 V or where future supply infrastructure changes are anticipated. Common dual-voltage configurations are 380 V Y / 660 V Y (for star only on both voltage levels), and 220 V Δ / 380 V Y (the classic delta-star dual-voltage arrangement). The terminal box is sized to accommodate the additional terminal links required for dual-voltage connection. Specify the required voltage combination at time of order. Dual-voltage models carry the same Ex d IIB T4 certification as single-voltage variants.

How does the YB2-4 compare to a standard Y2-4 in weight and dimensions?

The YB2-4 uses a cast-iron frame (not aluminium) for all frame sizes, because the additional wall thickness required to achieve the flameproof enclosure flame path geometry cannot be achieved with aluminium at standard IEC frame dimensions. The YB2-4 is therefore heavier than a Y2 motor of the same frame: typically 15 to 25% heavier, depending on frame size. The external frame dimensions and mounting hole pattern follow IEC 72-1 and are interchangeable with Y2 motors of the same frame designation, so the YB2-4 is a physical fit replacement for a Y2-4 in any installation. Terminal box position and cable entry location may differ and should be verified before ordering.

What is the lead time for large frame YB2-4 motors above 132 kW?

Frame sizes 250M through 315M in the YB2-4 range (75 kW to 200 kW) are typically built to order rather than held in finished goods stock. Standard lead time is 8 to 12 weeks from order placement. For project requirements with fixed delivery schedules, Korea Ever-Power recommends placing orders with at least 16 weeks lead time to allow for production scheduling, Ex certification documentation preparation, and pre-shipment factory acceptance testing. Contact Korea Ever-Power at the enquiry page with your required delivery schedule for a firm lead time commitment.

Request a Quote for YB2 4-Pole Explosion-Proof Motors

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Editor	Cxm