Eaton MD51E91 Motor isolation transformer - UL Listed
Part Number: MD51E91
Quick Summary
The Eaton MD51E91 Motor isolation transformer provides drive isolation for three-phase motor drives in industrial automation applications. Engineers often struggle with voltage transients and startup surges that shorten drive life and increase maintenance. UL Listed certification ensures safety compliance for control gear and distribution panels. The DT-3 dry-type design with 150°C rise and a 914D frame delivers reliable operation in harsh manufacturing environments, while the WS39 weather shield option helps protect equipment in dirty or damp facilities. This unit integrates with standard motor drives and control systems, supporting straightforward procurement, reduced downtime, and long-term uptime through proven isolation, voltage stability, and dependable performance in demanding production lines.
Product Information
Extended Description
MD51E91 Eaton: Drive Isolation Transformer, Ventilated, Dry Type Distribution, DT-3, Three-phase, PV: 460 delta, Taps: 1 at +5% FCAN, 1 at -5% FCBN, SV: 230Y/133V, 150°C, 51 kVA, Al windings, Frame: 914D, uses WS39
Product Name
Eaton Motor drive isolation ventilated transformer
Catalog Number
MD51E91
UPC
786680331350
Product Length/Depth
22 in
Product Height
39 in
Product Width
29 in
Product Weight
535 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
Aluminum
Design
DT-3
Frame
914D
Tap size
1 at +5% FCAN, 1 at -5% FCBN
Type
Dry Type Distribution, Drive Isolation Transformer
Frequency rating
60 Hz
Phase
Three-phase
Primary voltage
460 V
Secondary Voltage
230Y/133 V
Temperature rise
150 °C rise
Volt ampere rating
51 kVA
Weathershield
WS39
Commercial Distribution, Transformers, Volume 2, Tab 2
Eaton Specification Sheet - MD51E91
Selling Policy 25-000 - Distribution and Control Products and Services
Drive isolation reduces fault currents and voltage spikes between the power source and motor drives, protecting expensive drives and controllers. The impact is lower maintenance costs, reduced unplanned downtime, and improved safety in critical production lines. Dry-type DT-3 ventilation with a 914D frame supports reliable cooling in hot factories, and the 150°C rise spec helps maintain performance under load, while aluminum windings offer corrosion resistance. This combination translates to lower cooling costs and longer service intervals in continuous-operation environments. Voltage regulation via taps at +5% FCAN and -5% FCBN enables precise compensation for line drop and load changes, ensuring motors run at intended speed and torque. This reduces nuisance tripping and prolongs motor life in variable-load applications. Three-phase 460 V primary and 230Y/133 V secondary enable seamless integration with standard industrial power networks, with 60 Hz alignment simplifying compatibility with existing drives and panels. Weathershield WS39 option and UL Listed certification provide operational resilience and regulatory confidence for panel builders and end users. The 51 kVA rating supports moderate-to-large drives, while the 22 in / 39 in / 29 in footprint suits many enclosure configurations.
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FAQs
Install MD51E91 in a properly sized enclosure or footprint that accommodates its frame 914D and the 22 x 39 x 29 in dimensions. Connect the 460 V primary to the incoming three‑phase supply and land the 230Y/133 V secondary to the controlled loads. Use the +5% and -5% taps to fine‑tune voltage under load, and follow UL Listed wiring practices for control circuits and grounding.
Key specs include a 51 kVA VA rating, 60 Hz frequency, three‑phase configuration, primary 460 V, secondary 230Y/133 V, aluminum windings, DT‑3 dry‑type design, frame 914D, 150°C rise, and taps at +5% FCAN and -5% FCBN. It weighs approximately 535 lb and uses WS39 weather shielding to enhance protection in harsher environments.
Yes. MD51E91 provides drive isolation for three‑phase motor drives, helping to mitigate transients and startup surges common in conveyors and pumping systems. Its 51 kVA rating supports medium‑ to large‑duty drives, and the 460 V to 230Y/133 V voltages align with typical industrial power networks and control voltages used in these applications.
MD51E91 is UL Listed, confirming compliance with key electrical safety standards for distribution and control equipment. This certification supports safer integration in control panels and helps satisfy procurement and regulatory review requirements for industrial installations.
Expect low ongoing maintenance due to the dry‑type DT‑3 design and robust aluminum windings. The isolation function reduces drive faults and downtime, delivering a favorable return on investment through extended drive life, fewer field repairs, and improved system availability in demanding production environments.