Eaton MD51D91BCU Motor drive isolation transformer - UL
Part Number: MD51D91BCU
Quick Summary
Eaton MD51D91BCU motor drive isolation transformer delivers clean, reliable power for industrial motor drives. Power disturbances in automation lines can cause nuisance tripping, equipment stress, and costly downtime. UL Listed safety certification underpins reliability; the DT-3 dry-type design and WS19 weather shield enhance durability in harsh environments. This solution pairs seamlessly with standard three-phase power systems, delivering predictable performance, easier maintenance, and stronger protection for sensitive drives—supporting OEMs and end users with improved uptime and energy-management potential.
Product Information
Extended Description
MD51D91BCU Eaton: Dry Type Distribution Motor Drive Isolation Transformer DT-3 Three-phase 460 DELTA 2 at +2.5% FCAN 2 at -2.5% FCBN 230Y/133V 80°C 51 kVA Copper windings 916A 266S WS19 60 Hz 40 hp
Product Name
Eaton Motor drive isolation ventilated transformer
Catalog Number
MD51D91BCU
UPC
786680111037
Product Length/Depth
23.42 in
Product Height
48.56 in
Product Width
28.22 in
Product Weight
802 lb
Warranty
Eaton Selling Policy 25-000, one (1) year from the date of installation of the Product or eighteen (18) months from the date of shipment of the Product, whichever occurs first.
Certifications
UL Listed
Coil material
Copper
Design
DT-3
Frame
916A
Tap size
2 at +2.5% FCAN 2 at -2.5% FCBN
Type
Dry Type Distribution Motor Drive Isolation Transformer
Wiring connection
266S
Frequency rating
60 Hz
Kva Rating
51 kVA
Phase
Three-phase
Primary voltage
460 V
Secondary Voltage
230Y/133 V
Temperature rise
80 °C rise
Weathershield
WS19
The 51 kVA rating provides ample headroom for motor drives and related controls, reducing voltage sag during startup and load surges, which translates to fewer nuisance trips and smoother operation. This translates to measurable business impact: higher production continuity and lower maintenance intervention costs in automated lines, packaging, and processing plants. The MD51D91BCU features a 460 V primary and 230Y/133 V secondary, enabling direct integration with common plant power networks while supporting efficient power distribution and effective control of motor drive loads. Copper windings offer superior conductivity and thermal efficiency, while the DT-3 dry-type construction and WS19 weather shield deliver safe, maintenance-friendly installation in factory floors, switchgear rooms, or outdoors where permitted. The 80 °C rise rating provides robust thermal margins under high-load conditions, enhancing reliability. Tap changes at +2.5% and -2.5% allow tight voltage regulation to accommodate small supply fluctuations, improving drive performance and reducing risk of under- or over-voltage operation. Compatibility with standard wiring connection 266S and frame 916A simplifies mounting, reduces retrofit risk, and supports serviceability. Typical installation benefits include a compact footprint relative to capacity (23.42 in L × 28.22 in W × 48.56 in H) and a substantial 802 lb weight that signals solid, vibration-resistant construction. In practice, these features translate to lower total cost of ownership through improved reliability, easier spares management, and consistent drive performance across batches and shifts.
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FAQs
The MD51D91BCU is a three-phase, dry-type transformer designed for standard plant power distribution. Connect to a 460 V three-phase supply on the primary and tie the secondary to the motor drive input at 230Y/133 V. The unit uses 266S wiring and sits in a DT-3 enclosure with WS19 weather shield where required. Plan for proper clearance, cooling, and vibration isolation—mounting footprint is 23.42 in by 28.22 in with a 48.56 in height, and weight around 802 lb. Ensure compliance with local electrical codes and UL Listed safety requirements.
Key specs include a 51 kVA rating, 460 V primary, and 230Y/133 V secondary, 60 Hz, three-phase operation, and an 80 °C rise. These features support higher startup current handling and efficient energy transfer to drive systems while maintaining thermal margins. Copper windings improve conductivity and reduce losses, contributing to better overall efficiency. The +2.5%/−2.5% taps give limited voltage regulation to counteract supply fluctuations, helping maintain consistent motor performance.
This transformer is ideal for manufacturing environments that deploy motor drives for conveyors, pumps, and automated machining, where consistent power quality and drive isolation are critical. Industries such as packaging, metals, plastics, and food & beverage plants benefit from reduced electrical noise, improved drive reliability, and easier integration with existing Eaton components. The WS19 weathershield extends outdoor or harsh-floor installation viability, while the DT-3 dry-type design supports safe indoor use without oil.
The MD51D91BCU carries UL Listed certification, reflecting compliance with recognized safety standards for electrical equipment. When procuring, verify UL listing status and ensure the device is installed per UL guidelines, local electrical codes, and your plant’s safety policies. Consider enclosure protection, grounding, and clearances to maintain safe operation in automated environments and to preserve the transformer’s UL-listed status.
Maintenance is typically limited to periodic inspection of cooling paths, wiring connections, and enclosure integrity, given the oil-free DT-3 dry-type design. The transformer’s robust copper windings and copper windings reduce resistance losses, contributing to lower operating temperatures and fewer failures. ROI is driven by reduced downtime from voltage-induced drive faults, improved motor longevity, and easier spares management with a standard 51 kVA, 460 V to 230Y/133 V configuration.