Eaton MD550E91 Motor drive isolation transformer - UL Listed
Part Number: MD550E91
Quick Summary
The Eaton MD550E91 motor drive isolation transformer delivers clean, isolated power for industrial motor drives. Engineers often confront voltage spikes, startup transients, and overheating that jeopardize uptime and equipment life. UL Listed safety, the DT-3 dry-type design, and 150°C rise tolerance support compliant, reliable installations. As a three-phase, vented transformer with WS35 options, it enhances efficiency, reduces maintenance, and simplifies upgrades. This translates to lower lifecycle costs, easier compliance audits, and faster commissioning. Designed for industrial automation environments, it integrates with standard WS35 enclosures and supports global specifications. Its vented dry-type design minimizes heat buildup in crowded electrical rooms, improving cooling efficiency and safety.
Product Information
Extended Description
MD550E91 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, 550 kVA, Al windings, Frame: 919, uses WS35
Product Name
Eaton Motor drive isolation ventilated transformer
Catalog Number
MD550E91
UPC
786680331558
Product Length/Depth
36.23 in
Product Height
75 in
Product Width
44.2 in
Product Weight
2400 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
919
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
550 kVA
Weathershield
WS35
Commercial Distribution, Transformers, Volume 2, Tab 2
Eaton Specification Sheet - MD550E91
Selling Policy 25-000 - Distribution and Control Products and Services
Feature isIsolation capability that reduces transients and electrical noise, delivering a safer input to motor drives. Business impact is fewer VFD faults, lower cooling needs, and extended component life, especially for pumps, fans, and conveyors in harsh factory environments. Application spans industrial automation panels where reliable motor control is critical. Feature isVentilated dry-type design that improves cooling and allows higher continuous ratings in warm environments. Business impact includes reduced derating, lower fan loads, and easier compliance with ambient-temperature specs. Application includes outdoor or semi-enclosed switchgear and distribution panels within WS35-rated enclosures. Feature isHigh-capacity 550 kVA, 3-phase 60 Hz, 460 V primary and 230Y/133 V secondary with aluminum windings, frame 919. Business impact is robust headroom for motor starting, energy efficiency, and longer transformer life; Application includes large drives and process equipment. Feature isVoltage taps plus 5% and minus 5% options (1 at +5% FCAN, 1 at -5% FCBN) enabling precise site tuning. Business impact is reduced commissioning time and better local voltage matching. Application covers facilities with fluctuating supply or near-code requirements. Feature isDT-3 dry-type design with WS35 compatibility and UL Listed certification; Frame 919 supports straightforward mounting in standard racks. Business impact includes simplified installation, proven safety, and broad supplier support for maintenance. Application includes retrofit projects and new builds in industrial automation. Feature isWarranty and service policy aligned with Eaton’s 25-000 terms, ensuring parts availability and support. Business impact is lower risk during installation and predictable long-term costs; Application includes multi-site deployment and value-based procurement.
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FAQs
Install MD550E91 in a ventilated, UL Listed panel designed for dry-type transformers. Ensure adequate clearance for 75 inch height and 44.2 inch width, secure mounting for frame 919, and compatible WS35 enclosures where weather protection is needed. Verify 36.23 in depth alignment with cabinet spaces and provide proper ventilation to maintain the 150°C rise rating without derating.
The 460 V primary and 230Y/133 V secondary windings suit three-phase motor drives rated for standard factory supply and VFD inputs. This configuration supports common drive voltage requirements and enables voltage conversion for compatible motors, reducing startup transients and protecting drive electronics. Ensure the motor and drive combination remains within the 550 kVA rating for peak loading scenarios.
Yes. The DT-3 dry-type design is engineered for industrial rooms with elevated temperatures, and the WS35 weathershield option provides enclosure versatility for outdoor or semi-exposed installations. With aluminum windings and a 150°C rise rating, the transformer maintains performance under demanding loads while minimizing cooling demands in constrained spaces.
The MD550E91 is UL Listed, signifying compliance with safety and performance standards. Eaton offers a one-year warranty from installation or 18 months from shipment, whichever occurs first, under policy 25-000, providing coverage for manufacturing defects and delivering peace of mind during installation and operation.
The transformer delivers predictable maintenance needs with a robust dry-type design and modular frame 919 mounting. ROI comes from improved uptime, reduced drive faults, and simplified commissioning, especially in multi-site deployments. With premium efficiency and durable aluminum windings, long-term operating costs stay controlled while meeting regulatory requirements.