MK075KB Hammond 75 kVA Transformer, 480V to 208Y/120V, 3-Phase NEMA 3R Direct Replacement

MK075KB Hammond 75 kVA Transformer, 480V to 208Y/120V, 3-Phase NEMA 3R Direct Replacement

When you need to pull 208Y/120V off a 480V three-phase feed, the Hammond MK075KB is the unit that handles it. This 75 kVA dry-type transformer takes 480V delta on the primary and gives you a grounded 208Y/120V wye secondary with a neutral, so you can land your panel feeders and 120V branch circuits straight off the X terminals. The NEMA 3R enclosure means you can set it indoors in a mechanical room or outside on a pad without an extra weather house.

It is aluminum wound with a 150°C rise on a 220°C insulation system, self-cooled, and carries six 2.5% taps on the primary so you can trim for a high or low incoming line. If you are replacing an older 480-208Y/120V dry-type in the same footprint, this drops into the same role.

Common Applications

• Feeding a 208Y/120V panel from a 480V three-phase service
• Adding 120V receptacle and lighting circuits to a 480V-only building
• Direct replacement for an existing 75 kVA 480-to-208Y/120V dry-type transformer
• Outdoor pad or rooftop installs where a 3R-rated unit is required

Key Features

• 480 to 208Y/120V step-down: Delta primary to grounded wye secondary with neutral for 120V loads.
• NEMA 3R enclosure: Rainproof and louvered, so it goes in indoors or outdoors as is.
• Six primary taps: Two above and four below nominal, 2.5% each, to dial in your line voltage.
• Aluminum windings: Full 75 kVA rating. Spec MK075KBC if the job calls for copper.
• Self-cooled: Class AA, no fans, no auxiliary power to run.
• UL Listed and CSA Certified: Passes inspection for general distribution use.

Specifications

• Manufacturer: Hammond Power Solutions
• Catalog Number: MK075KB
• Power Rating: 75 kVA
• Phase: 3-Phase
• Frequency: 60 Hz
• Primary Voltage: 480V Delta
• Secondary Voltage: 208Y/120V
• Winding Material: Aluminum
• Temperature Rise: 150°C
• Insulation System: 220°C
• Cooling Class: AA (self-air-cooled)
• Impedance: Approximately 5%
• Primary Taps: Six 2.5% taps (2 above, 4 below nominal)
• Enclosure: NEMA 3R, ANSI 61 grey finish
• Mounting: Floor mount
• Certifications: UL Listed, CSA Certified

Product Identification

• UPC/GTIN: 803423013905
• Dimensions (H x W x D): 38 in x 26 in x 21 in
• Weight: Approximately 575 lb

FAQ

What does the MK075KB step down to? It takes 480V three-phase delta on the primary and puts out 208Y/120V on the secondary, giving you both 208V three-phase and 120V single-phase.

Can I mount the MK075KB outside? Yes. The NEMA 3R enclosure is rated for outdoor use, so it can sit on a pad or rooftop without additional weather protection.

Is this aluminum or copper wound? The MK075KB is aluminum wound. If your spec requires copper, order the MK075KBC.

Does it have taps? Yes. It comes standard with six 2.5% primary taps, two above and four below nominal, to compensate for high or low incoming voltage.

Is the MK075KB a direct replacement for an older 480-208Y/120V transformer? In most cases yes, for a same-rated 75 kVA dry-type. Confirm the enclosure footprint and lug locations against your existing unit.

What is the current-production version? The NMK075KB is the DOE 2016-compliant successor with the same ratings. Use it where current efficiency code applies.