STAMFORD S9LV Low Voltage Alternator 2430-4400 kVA

Digital regulation and PMG excitation for multi-megawatt sets

The STAMFORD S9LV is the low-voltage version of the S9 alternator, rated 2430 to 4400 kVA at 50 Hz and 2132 to 4220 kW at 60 Hz across class H, class F continuous and standby ratings. The brochure gives a maximum continuous output of up to 4250 kVA at 400 V and 50 Hz, with optimised efficiency and power density that let the same power fit a smaller alternator footprint.

It is the alternator for data-centre standby halls, combined heat and power plants and large prime-power stations. The DM110 digital AVR is fitted as standard with PMG excitation, giving the sets paralleling capability and the control functions that large installations expect, such as power factor control built into the regulator.

Technical specifications

S9LV ratings at 400 V, 50 Hz (winding 311 unless noted)

Ratings are subject to change according to the brochure; windings 312 are marked separately.

Choosing between the S-Range frames at the top end

The S9LV covers the largest low-voltage sets in the S-Range. Below it, the S7K handles about 3 MVA, and the S6 about 1.4 MVA. At this size the voltage regulator choice matters: DM110, DECS150 and UNITROL are all shown with current sensing, controlled short circuit, frequency detection and built-in power factor control, and a no-AVR build is also listed. For rating selection, use the class H 125/40 column for prime or continuous sets, the standby 150/40 column only for emergency-only duty, and the class F 105/40 column when a lower temperature rise is wanted from the same frame, for example on a hot site.

Build options

Factory options include an anti-condensation heater, bearing RTD on each bearing, an air inlet filter at the non-drive end and terminal box (which needs the P80 terminal box), a radio-frequency interference suppressor kit, an excitation loss module and a diode failure detector.

How the STAMFORD S9LV works

A diesel or gas engine turns the rotor of the alternator. A small permanent magnet generator on the same shaft gives power to the DM110 regulator. The regulator feeds the exciter, which sets the rotor field and holds the output voltage steady as the load changes.

Where the S9LV is used

• Data-centre standby halls
• Combined heat and power plants
• Large prime-power stations
• Paralleled generator sets
• Diesel and gas engine sets

Selection checklist for the S9LV

• Core size from C to G
• Continuous or standby rating
• Voltage from 380 to 690 V
• Frequency of 50 or 60 Hz
• Voltage regulator
• Bearing arrangement
• Winding temperature sensors
• Engine type

Installation, commissioning and maintenance notes for the S9LV

Couple the alternator to the engine through the SAE adaptor and align the shafts. Connect the six terminals and the regulator wiring. Check the winding resistance before the first run. Set the voltage and test the paralleling. Keep the air inlets clean.

Requesting a quotation for the STAMFORD S9LV

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

STAMFORD S9LV kVA range

The range is 2430 to 4400 kVA at 50 Hz.

STAMFORD S9LV continuous rating

The continuous rating at 400 V and 50 Hz is 2800 to 4250 kVA.

STAMFORD S9LV 60 Hz rating

The continuous rating at 480 V and 60 Hz is 2680 to 4080 kVA.

STAMFORD S9LV voltage range

The voltage range is 380 to 690 V.

STAMFORD S9LV poles and winding

The alternator has four poles and a wire wound design.

STAMFORD S9LV regulator

The DM110 digital regulator is standard, with DECS150 and UNITROL as options.

STAMFORD S9LV excitation

The excitation system is the DM110 with a PMG.

STAMFORD S9LV bearings

A double bearing is standard and a single bearing is optional.

STAMFORD S9LV insulation

The insulation is class H.

STAMFORD S9LV ingress protection

The ingress protection is IP23.

Alternator records for the STAMFORD S9LV

Record the frame, the winding number and the insulation resistance at each test.

Choosing the right STAMFORD S9LV core

Choose the core from the kVA column that matches the duty, using the class H column for prime sets.

Documents and quotation

Seven Star LLC supplies STAMFORD S9LV alternators for large genset builds, against a full specification. Provide kVA, voltage, frequency, engine and coupling, AVR and options. See Diesel Generator Spare Parts for related components, or the Cummins C1000D5B 1000 kVA diesel generator set for a 1 MVA reference set. Confirm ratings and drawings against the final data supplied with the quotation.

The brochure also shows the S-Range overview from 7.5 kVA up to 5,600 kVA across the S0, S1, S4, S5, S6, S7 and S9 families, with standby, combined heat and power and prime power as the applications named for the S9LV. Ratings are subject to change, and the 312 windings are marked separately.