STAMFORD S1 Low Voltage Alternator 35-62.5 kVA

Step up from the S0 for 35 to 62.5 kVA gensets

The STAMFORD S1 takes the S-Range from 35 up to 62.5 kVA at 50 Hz and 42 to 75 kVA at 60 Hz. It is the alternator for the 40 to 60 kVA generator sets that supply workshops, camps, clinics, telecom hubs and light industrial plant, and it shares the S0 platform: four poles, wire-wound construction, a single bearing and the analogue AS540 AVR.

All S1 models use the S1L2 core. The brochure lists the three-phase ratings in five steps, from S1L2-J1 to S1L2-Y1, so a set builder can match the alternator closely to the engine output instead of over-sizing. STAMFORD describes the S-Range as lighter and more compact than the earlier alternators it replaces, with a robust steel and cast iron exterior and enhanced motor starting capability without added length.

Technical specifications

Three-phase ratings at 400/415 V, 50 Hz, continuous 125/40

At 480 V, 60 Hz the same five models are rated 42, 48, 54, 60 and 75 kVA. * Auxiliary winding option available (winding 711).

Matching the S1 to the engine and the duty

Choose the rating from the engine kW at the generator frequency, then check which duty column applies. The brochure gives continuous 125/40, continuous 105/40, standby 150/40 and standby 163/27 figures for each model; for example the S1L2-R1 is 50.0 kVA continuous at 125/40 and 55.0 kVA in the 163/27 standby column at 400/415 V, 50 Hz. Select a standby figure only when the set will not run as a prime unit.

Service life and testing

Each alternator is tested for declared performance before despatch, and the components went through 9,000 hours of highly accelerated life testing. The stated design life is a minimum of 20,000 hours. IP23 protection is standard; for humid sites the optional anti-condensation heater listed in the brochure is worth specifying at order stage.

Single-phase S1 machines are listed too: at 50 Hz and 230 V the S1L2-K1 is rated 25 kVA and the S1L2-R1 30 kVA, and at 60 Hz and 240 V the S1L2 models run from 27 kVA (G1) to 36.5 kVA (N1) on winding 06. STAMFORD lists compliance with codes and standards globally, with UL certification and IEC and NEMA compliance, a choice of AVR position and centre height, and accessories that include space heaters, a diode failure detector and a remote trimmer.

How the STAMFORD S1 alternator works

The STAMFORD S1 is a four-pole alternator driven by a diesel or gas engine. A small exciter on the same shaft makes the field current for the main rotor, so no brushes are needed. The AS540 analogue AVR senses the output voltage on two phases and adjusts the exciter field to hold the voltage steady as the load changes. The single bearing design bolts directly to the engine flywheel through the SAE adaptor, which keeps the set short.

Where the STAMFORD S1 is used

• Generator sets of 40 to 60 kVA
• Workshops and camps
• Clinics and small hospitals
• Telecom hubs
• Light industrial plant

Selection checklist for the STAMFORD S1

• Rating in kVA at 50 Hz or 60 Hz
• Voltage of 400/415 V or 480 V
• Model from S1L2-J1 to S1L2-Y1
• Duty: continuous or standby
• SAE adaptor: 3, 4 or GM
• Auxiliary winding option for motor starting
• Anti-condensation heater
• Current transformers if needed

Installation, commissioning and maintenance notes

Match the SAE adaptor and the coupling to the engine flywheel and align the set with care. Connect the twelve terminals for the voltage needed. Run the set unloaded and check the voltage and frequency. Then apply load in steps. Keep the air path clean and dry, as the IP23 enclosure is not made for wet locations, and fit the heater where the set sits idle in damp air.

Requesting a quotation for the STAMFORD S1

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

STAMFORD S1 ratings

At 400/415 V and 50 Hz the five models are 35, 40, 45, 50 and 62.5 kVA. At 480 V and 60 Hz they are 42, 48, 54, 60 and 75 kVA.

STAMFORD S1 construction

It has four poles, wire-wound construction, insulation class H and IP23 protection. It is self-exciting, and an auxiliary winding is optional.

STAMFORD S1 duty columns

The brochure gives continuous 125/40, continuous 105/40, standby 150/40 and standby 163/27 figures. The S1L2-R1 is 50.0 kVA continuous at 125/40 and 55.0 kVA in the 163/27 standby column.

STAMFORD S1 options

Options include one-phase reconnection, an anti-condensation heater and flexible foot mounting for the S1L2 180-225 mm frame.

Alternator records for STAMFORD S1

Keep the nameplate data, the insulation resistance readings and the load test results with the set file.

Choosing the right STAMFORD S1 model

Choose the rating from the engine kW at the generator frequency, and use a standby figure only when the set is not a prime unit.

Documents and quotation

Seven Star LLC supplies STAMFORD S1 alternators against your genset specification. Send kVA, voltage, frequency, engine model with SAE housing and whether the set is standby or continuous. See Diesel Generator Spare Parts for other generator components, or the Cummins C150D5 150 kVA diesel generator set for a complete set. Verify the winding, adaptor and foot dimensions against the confirmed order data.