STAMFORD UC22 Low Voltage Alternator 26-103 kVA

A grid-code capable frame for the 30 to 100 kVA class

The STAMFORD UC22 is the smallest alternator in the UC range, rated 26 to 103 kVA with a maximum continuous output of 85 kVA at 50 Hz and 103 kVA at 60 Hz. STAMFORD describes its proven, robust design as the smallest range offered for grid-code applications. It is a four-pole machine only, with a voltage range of 380 to 690 V, and it suits generator sets for telecom sites, small plants, farms and rental fleets.

The owner manual describes the UC22 and UC27 as brushless rotating-field alternators, built to BS 5000 Part 3 and international standards and available up to 690 V at 50 Hz (1500 rpm) or 60 Hz (1800 rpm). They are self-excited as standard, with excitation power taken from the main output windings through an SX460 or AS440 AVR, and the UC22 can also be supplied with specific windings and a transformer-controlled excitation system.

Technical specifications

Product options

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

UC22 and UC27 compared

The UC27 is the larger frame of the same range. The table below uses the specification and mechanical data printed on the product pages and in the owner manual.

Installation points from the manual

The manual stresses that air inlets and outlets must not be blocked, that the intake-to-outlet pressure difference stays within 6 mm water gauge, and that belt drives require correct tensioning or bearing wear will be excessive. Insulation resistance should be tested before the first start. Recommended service spares to hold with the machine include a diode set (RSK2001) and a spare AVR; the AS440 AVR part number given is E000-24403/1P. A hologram on the tracking label can be checked on the STAMFORD verification page with a unique 7-character code, a useful step when a purchase must be confirmed as genuine, and the nameplate states the intended operating parameters of the alternator.

How the STAMFORD UC22 works

The engine turns the rotor of the alternator. A small exciter on the same shaft gives the rotor field current through rotating diodes, so there are no brushes. The AVR changes the exciter field to hold the output voltage. In the self-excited design the AVR takes its power from the main windings.

Where the UC22 is used

• Telecom site generator sets
• Small industrial plants
• Farms
• Rental fleets
• Sets that need a grid-code capable machine

Selection checklist for the UC22

• Output of 26 to 103 kVA
• Frequency of 50 or 60 Hz
• Voltage of 380 to 690 V
• AVR type
• Single or double bearing
• Air filter need
• Heaters against condensation
• Ambient temperature and altitude

Installation, commissioning and maintenance notes for the UC22

Align the alternator carefully with the engine. Keep the air path clear, as the machine needs a minimum air flow. Dry out the windings if they have been in damp air. Check the bearings and the AVR at each service. Do not use it outdoors without extra protection.

Requesting a quotation for the STAMFORD UC22

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

UC22 power range

The UC22 is rated from 26 to 103 kVA.

UC22 continuous output

The continuous output is 85 kVA at 50 Hz and 103 kVA at 60 Hz.

UC22 poles

It is a four-pole machine only.

UC22 insulation

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

UC22 air flow

The minimum air flow is 0.216 m3/s at 50 Hz and 0.281 m3/s at 60 Hz.

UC22 side load

The maximum side load is 408 kg, and the shaft extension is 110 mm.

UC22 environment

It works at ambient 15 degrees C below zero to 40 degrees C and below 1000 m altitude.

UC22 options

Options include a double bearing, air filters, thermistors, heaters and PMG excitation.

Alternator records for the UC22

Record the winding resistance, the bearing hours and the date of each service.

Choosing the right UC22 AVR

Use the AS440 as standard, or choose an MX321 or MX341 with PMG as the optional AVRs.

UC22 shaft bearings

The service bearing numbers are 45-0867 at the non-drive end and 45-0365 at the drive end.

UC22 excitation

The UC22 is self-exciting, and the AVR takes its power from the main windings.

UC22 noise level

The owner manual gives a noise level of up to 106 dB(A).

Documents and quotation

Seven Star LLC supplies STAMFORD UC22 alternators on request. Send kVA, voltage, frequency, engine and SAE housing, AVR preference and duty. The owner manual is linked on this page. Related components are listed under Diesel Generator Spare Parts; for a complete set see the Cummins C150D5 150 kVA diesel generator set. Confirm winding, rating and mounting data against your final order.

The 78-page owner manual covers safety, installation, coupling to the engine, commissioning, maintenance and recommended service parts, so it also works as the installation and maintenance guide for both UC frames. Read the environmental limits before specifying a site, since the standard rating is for ambient up to 40 degrees C.