Brand: STAMFORD

STAMFORD UC27 Low Voltage Alternator 75-312 kVA

Name: STAMFORD UC27 Low Voltage Alternator – Manual & Quote
Brand: STAMFORD
SKU: STAMFORD UC27

Description

A 75 to 312 kVA alternator for gensets, CHP and marine duty

The STAMFORD UC27 is the larger frame of the UC range, with a kVA range of 75 to 312 and a maximum continuous rating of 250 kVA at 50 Hz and 312 kVA at 60 Hz. The product page lists grid code, combined heat and power, marine, mobile construction, utility works and the telecom industry as the applications for this four-pole, 380 to 690 V machine.

It follows the same UC platform as the UC22: brushless rotating field, built to BS 5000 Part 3, self-excited by default using the AS440 or SX460 AVR, and available with PMG excitation through the MX341 or MX321. A dedicated UCD version exists for the UC27 only, according to the model naming table in the manual, and a UCG type denotes grid-code compliance.

Technical specifications

Parameter	Specification
Range	STAMFORD UC27
kVA range	75-312 kVA
50 Hz continuous	250 kVA
60 Hz continuous	312 kVA
Voltage range	380-690 V (low voltage)
Poles	4
AVR	AS440 as standard; SX460 per owner manual
Winding pitch	2/3
Insulation class	H
Excitation system	Self-exciting
Ingress protection	IP23
Environment	Ambient -15 to 40 degrees C, humidity below 70 percent, altitude below 1000 m
Minimum air flow	0.514 m3/s at 50 Hz; 0.617 m3/s at 60 Hz (UCD27: 0.58 / 0.69)
Maximum side load	510 kg (5000 N); shaft extension 140 mm
Service bearings	NDE 45-0868; DE 45-0367
Noise	Up to 106 dB(A) maximum (manual)

Options and regulators

AVR options are the MX321 with PMG, MX341 with PMG, no AVR, or the VITA 05 digital regulator. Build options: double bearing, IP23 air filters, thermistors, 1-phase re-connection, 3-phase sensing, anti-condensation heaters and PMG excitation.

UC22 and UC27 side by side

Core letters C to H are used in the UC27 name, and the manual publishes per-core winding data for the UC27C to UC27H. Use these only for testing against a measured machine, not for selection.

Maintenance and spares

The manual recommends holding service spares in critical applications: a diode set, an AVR and bearings. For the UC27 the bearing numbers are NDE 45-0868 and DE 45-0367. AVR numbers given in the manual are E000-24403/1P (AS440), E000-23212/1P (MX321), E000-23412/1P (MX341) and E000-24602/1P (SX460). The main vibration frequencies are 25 Hz at 1500 rpm and 30 Hz at 1800 rpm, and set designers must keep vibration within BS 5000-3 and ISO 8528-9 limits. Before a first start the manual asks for an insulation resistance test and, where an anti-condensation heater is fitted, a 500 V test of the heater element with a minimum of 10 megohms for a new heater. The hologram on the tracking label carries a 7-character code that can be entered on the STAMFORD verification page to confirm the machine is genuine.

How the STAMFORD UC27 works

A prime mover turns the rotor of the alternator. The AVR feeds a small exciter, and the exciter feeds the main field through a rotating rectifier. This makes a field in the rotor and a voltage in the stator windings. The AVR watches the output and adjusts the exciter to hold the voltage steady as the load changes.

Where the STAMFORD UC27 is used

Diesel and gas gensets
Combined heat and power plants
Marine installations
Mobile construction power
Telecom sites and utility works

Selection checklist for the STAMFORD UC27

Power in kVA at 50 or 60 Hz
Voltage in the 380 to 690 V range
Core size C to H
Self-excited or PMG
AVR type
Single or double bearing
Air filters and heaters
Grid code need

Installation, commissioning and maintenance notes for the STAMFORD UC27

Align the alternator with the engine and check the side load on the shaft. Connect the output cables and the AVR leads. Set the voltage with the AVR trimmer at no load. Run a load test and watch the voltage. Keep the cooling air path clear and follow the bearing service intervals in the manual.

Requesting a quotation for the STAMFORD UC27

Please send the kVA rating, the voltage, the frequency and the excitation type. Seven Star LLC serves industrial customers in Oman and the GCC and replies with a quotation based on the information provided.

STAMFORD UC27 power range

The UC27 covers 75 to 312 kVA.

STAMFORD UC27 continuous rating

The continuous rating is 250 kVA at 50 Hz and 312 kVA at 60 Hz.

STAMFORD UC27 poles

The alternator has four poles.

STAMFORD UC27 insulation

The insulation is class H and the winding pitch is 2/3.

STAMFORD UC27 protection

The ingress protection is IP23.

STAMFORD UC27 ambient conditions

The ambient range is minus 15 to plus 40 degrees C, below 1000 m altitude.

STAMFORD UC27 cooling air

Minimum air flow is 0.514 m3/s at 50 Hz and 0.617 m3/s at 60 Hz.

STAMFORD UC27 AVR options

The options are the MX321 and MX341 with PMG, no AVR, or the VITA 05 digital regulator.

STAMFORD UC27 bearings

The service bearings are NDE 45-0868 and DE 45-0367.

STAMFORD UC27 side load

The maximum side load is 510 kg.

Alternator records for the STAMFORD UC27

Record the running hours, the bearing change date and the winding test results.

Choosing the right STAMFORD UC27 build

Choose PMG excitation when the set must hold voltage under heavy motor starting.

Documents and quotation

Seven Star LLC supplies STAMFORD UC27 alternators on request. Send kVA, voltage, frequency, engine, SAE housing, AVR preference and duty. The owner manual is attached here. See Diesel Generator Spare Parts for related parts or the Cummins 312/315 kVA diesel generator set for a complete 312 kVA set. Confirm all data against the nameplate and your final order. For the UC27 the product page lists grid code, combined heat and power, marine, mobile construction, utility works and telecom use.

The side load and air flow figures above come from the owner manual tables, and the 78-page manual also covers safety, installation, coupling to the engine, commissioning, maintenance and recommended service parts. Read its environmental limits before specifying a site, since the standard rating assumes ambient up to 40 degrees C and altitude below 1000 m.

Datasheets & Documents

Manual STAMFORD UC22 and UC27 alternators owner manual A040J848 Issue 9 (EN, 78 pages) Download

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About brand

STAMFORD, branded STAMFORD | AvK, is the alternator maker of Cummins Generator Technologies, building brushless AC alternators and automatic voltage regulators from 7.5 to 11,200 kVA. Its heritage runs back to 1904, when the Cutting Brothers started an electrical engineering business in Stamford, England. Seven Star LLC, an independent supplier in Muscat, sources these alternators and regulators for generator builders and plant owners in Oman and the GCC.

Alternators and AVRs listed here

The pages cover the S-Range alternators S0, S1, S4, S5, S6, S7K and S9LV, the UC22 and UC27 frames, and the AS480, MX321, MX341, MX342, SX460 and DM110 voltage regulators. Each page carries the ratings and specification from the maker brochure, datasheet or owner manual, including options as printed.

Where these alternators are used

The maker names data centres, marine, telecoms, standby and critical protection, combined heat and power, rail and prime power as typical applications, on diesel and gas engines. In the Gulf these are the same standby and prime-power sets used on camps, plants and pumping stations.

Ordering parts and alternators: what we need

For an alternator, send the model, serial number, winding number, kVA, voltage and frequency from the nameplate. For a regulator, send the code printed on the existing board and the alternator model, because the right replacement depends on the excitation system.