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HC / HCI Series UCI / UCM Series UCD / UCDI Series P / PI Series How to Order
Frame Series
HC / HCI Series
Single bearing, drip-proof alternator ends for smaller commercial and industrial generator sets. The HC and HCI series are among the most widely deployed Stamford frames in the 8–100kVA range.
Single Bearing
HC4
4-Pole Single Bearing Alternator End

Compact single-bearing alternator end for smaller standby and prime power sets. Suitable for single-phase and three-phase output configurations. Widely used on light commercial generator sets.

Output Range8–22 kVA
Poles4
Voltage110–480V configurable
Frequency50 / 60 Hz
HC4
Single Bearing
HCI4
4-Pole Single Bearing Alternator End

Higher-output single-bearing end in the HC family. The HCI4 is a standard choice for commercial standby sets in the 25–65kVA range. Available in multiple voltage configurations.

Output Range25–65 kVA
Poles4
Voltage110–480V configurable
Frequency50 / 60 Hz
HCI4
Single Bearing
HCI5
4-Pole Single Bearing Alternator End

The largest frame in the HC single-bearing family. The HCI5 handles outputs up to 100kVA, making it suitable for mid-range commercial standby applications including hospitals and commercial buildings.

Output Range65–100 kVA
Poles4
Voltage110–480V configurable
Frequency50 / 60 Hz
HCI5
Frame Series
UCI / UCM Series
The UCI and UCM are Stamford's most widely deployed two-bearing alternator ends, covering 10–250kVA. They are the standard choice for commercial standby sets at hospitals, data centers, and commercial buildings.
Two Bearing
UCI2
4-Pole Two Bearing Alternator End

Entry-level two-bearing UCI frame for smaller commercial sets. Provides greater mounting flexibility than the single-bearing HC series and suits a wide range of engine configurations.

Output Range10–30 kVA
BearingTwo bearing
Voltage110–480V configurable
Frequency50 / 60 Hz
UCI2
Two Bearing
UCI3
4-Pole Two Bearing Alternator End

Mid-range UCI frame delivering 30–100kVA. One of the most common replacement ends in the market — found on generator sets from all major OEMs. Available new and remanufactured.

Output Range30–100 kVA
BearingTwo bearing
Voltage110–480V configurable
Frequency50 / 60 Hz
UCI3
Two Bearing
UCI4
4-Pole Two Bearing Alternator End

The UCI4 is the workhorse of the commercial standby market — covering 100–200kVA, it is found on the majority of hospital, data center, and commercial building generator sets in the US.

Output Range100–200 kVA
BearingTwo bearing
Voltage110–480V configurable
Frequency50 / 60 Hz
UCI4
Two Bearing
UCM5
4-Pole Two Bearing Alternator End

Upper range of the UCI/UCM family, delivering up to 250kVA. The UCM5 suits larger commercial standby sets and light industrial prime power applications requiring higher continuous output.

Output Range150–250 kVA
BearingTwo bearing
Voltage110–480V configurable
Frequency50 / 60 Hz
UCM5
Frame Series
UCD / UCDI Series
High-output two-bearing alternator ends delivering up to 500kVA. The UCD and UCDI series are specified for large commercial standby and prime power applications where higher continuous ratings are required.
Two Bearing
UCD5
4-Pole Two Bearing Alternator End

Entry-level UCD frame delivering 250–350kVA. A step up from the UCM family for applications requiring higher sustained output ratings. Common on large commercial standby installations.

Output Range250–350 kVA
BearingTwo bearing
Voltage110–480V configurable
Frequency50 / 60 Hz
UCD5
Two Bearing
UCD6
4-Pole Two Bearing Alternator End

Upper-range UCD frame for demanding commercial and light industrial applications. The UCD6 delivers up to 500kVA and is commonly specified for large hospital, data center, and utility standby sets.

Output Range350–500 kVA
BearingTwo bearing
Voltage110–480V configurable
Frequency50 / 60 Hz
UCD6
Two Bearing
UCDI Series
Industrial Two Bearing Alternator End

Industrial-specification UCD frame for continuous prime power and demanding duty cycles. The UCDI features enhanced insulation systems and a higher ingress protection rating for industrial environments.

Output Range250–500 kVA
DutyPrime / Continuous
InsulationClass H enhanced
Frequency50 / 60 Hz
UCDI
Frame Series
P / PI Series
Stamford's premium single-bearing range for high-output prime and standby power applications, covering up to 2000kVA. The P and PI series are specified for large industrial, utility, and mission-critical facilities.
Single Bearing Premium
P7
4-Pole Premium Single Bearing End

Entry-level P series alternator end, delivering 500–800kVA in a robust single-bearing design. Suited to large commercial standby and prime power applications requiring high output in a compact package.

Output Range500–800 kVA
BearingSingle bearing
InsulationClass H
Frequency50 / 60 Hz
P7
Single Bearing Premium
P8
4-Pole Premium Single Bearing End

Mid-range P series delivering 800–1250kVA. The P8 is a common specification for large data center and industrial standby sets. Available with PMG excitation for enhanced fault-ride performance.

Output Range800–1250 kVA
BearingSingle bearing
PMG OptionAvailable
Frequency50 / 60 Hz
P8
Single Bearing Premium
P9
4-Pole Premium Single Bearing End

High-output P series delivering 1250–2000kVA. Specified for the largest commercial and industrial generator sets — utility substations, large data centers, and mission-critical facilities requiring the highest output in a single alternator end.

Output Range1250–2000 kVA
BearingSingle bearing
PMG OptionAvailable
Frequency50 / 60 Hz
P9
How To Order

What We Need From You

To supply the correct replacement alternator end, we need a few details from your existing unit's nameplate. The more information you can provide, the faster we can quote.

Frame / Model Number
The Stamford frame designation (e.g. UCI274E, HCI434F). Found on the nameplate on the alternator body.
kVA Rating
Standby and/or prime power rating in kVA. This ensures the replacement end matches the capacity of the original.
Voltage & Frequency
Output voltage (e.g. 120/208V, 277/480V) and frequency (50 or 60Hz). Critical for correct winding configuration.
Coupling Type
Single or two-bearing, SAE disc size, and engine bell housing size. Ensures the replacement end mates correctly to your engine.
Serial Number
The Stamford serial number allows us to look up the exact factory specification of your original alternator end.
New or Remanufactured
We supply both new OEM-specification ends and fully remanufactured units. Let us know your preference and we will quote both options.
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