Ordered the wrong unit, or not sure if a product is right for you? Our free exchange policy has you covered! We’ll cover freight both ways and send you a replacement free of charge.

3-Phase 208 D - 480 Y 277 (Step-Up Drive Isolation Transformer)

Size Guide SKU # MIT-DIT-140
NEW:  $1,975.00 IN STOCK CALL FOR LEAD-TIME 866-719-1882
USED: $1,975.00 IN STOCK
(${ savings }% savings!)

Delivers in 5-7 business days

Primary Voltage: 208 D

Secondary Voltage: 480 Y 277 (Drive-Isolation Transformer)

Maddox Drive-Isolation Transformers are designed to meet the rugged demands of both AC and DC variable speed drives and provide the required voltage change.

The separate windings provide electrical isolation between the incoming power and the SCR or VFD load. The windings are designed to withstand overcurrent at 150% of the rated load for 60 seconds or 200% of the rated load for 30 seconds, as well as minor harmonic noise at or below K-Factor 4. Standard duty cycle is one start every two hours.

Drive Isolation Transformers are sized to match standard motor horsepower and voltage ratings.

Standard sizes range from 5 to 600 HP in six standard voltages.

kVA Sizing Recommendation: At least 20% above the rated horsepower on the motor.

Transformer Specifications:

  • CSA and UL Approved
  • 60 Hz Frequency
  • 150°C Temperature Rise
  • 220°C Insulation Class
  • Primary Adjustment Taps 1 above, 1 below in 5% increments
  • Electrostatically Shielded
  • High Efficiency Aluminum Windings
  • Vacuum pressure Impregnated Windings
  • NEMA 3R Outdoor/Indoor Enclosure
  • DOE Exempt
  • Wall Mountable up to 75kVA
  • Lugs included up to 75 kVA

Exact size and shape to vary. Transformers ordered for indoor use may be provided with outdoor enclosure depending on stock. Transformer may appear different than pictured.

Need something different? Contact us for a custom quote: 600vsales@maddoxtransformer.com

Download instruction manual

Buck boost transformer

Approximate Enclosure Dimensions & Weights:

kVA Dimensions Weight (lbs)
11 21.5in(H), 19.38in(W), 20.2in(D) 150
14 21.5in(H), 19.38in(W), 20.2in(D) 180
20 28.75in(H), 23.9in(W), 25in(D) 225
27 28.75in(H), 23.9in(W), 25in(D) 280
34 28.75in(H), 23.9in(W), 25in(D) 305
40 28.75in(H), 23.9in(W), 25in(D) 315
51 28.75in(H), 23.9in(W), 25in(D) 370
63 38in(H), 26in(W), 21in(D) 510
75 38in(H), 26in(W), 21in(D) 570


Shipping Rates
Shipping rates vary, but generally range between 5-10% of the total purchase price.

Shipping From
Transformers shipping from stock deliver within 3-5 business.  Maddox has 22 regional fulfillment centers so delivery is never a few days out!

Maddox Fulfillment Centers

Returns and Exchanges

Our policy lasts 30 days. If 30 days have gone by since your purchase, we unfortunately cannot offer you a refund or exchange. We still may be interested in buying the unit back. We require proof of purchase in order to process a return or exchange.


To be eligible...

Read more here: Shipping, Return and Refund Policy

5 Year Warranty

Buy with confidence. All new and used Maddox transformers are tested and come with a full 5 year warranty against defects. If you experience any problems just give us a call and receive a replacement, free of charge. We'll even pay the shipping!