LSA 40S3 1-Phase - Leroy Somer | 15 kW

Model. The LSA 40S3 1-Phase is a Leroy Somer LSA 4-pole alternator. In Leroy Somer's LSA nomenclature 40 is the frame and S3 is the core length: the frame fixes the stator bore and shaft centre height, and the core code fixes how much active iron is stacked into that bore. This one uses the short core, stack position 3 within that family. A longer core in the same frame buys more output at the same temperature rise, which is why the same frame number appears across a spread of ratings. It is wound for single-phase service at 50 Hz. Electrical rating. At 0.8 power factor lagging this machine is rated 15 kW, which is 18.8 kVA, delivered as single-phase at 230 V 50 Hz. At 230 V that is 81.5 A through the line and the neutral. Small frames like this are sensitive to load power factor: running them well below 0.8 PF pushes the field current up and the stator current up at the same kW, so the nameplate kVA is the number to design to. The 1500 rpm figure is synchronous speed, so there is no slip and no speed-dependent voltage droop. Frame and core. The 40 frame carries the S3 core. Frame size fixes the stator bore and the shaft centre height; the core length fixes how much active iron sits in that bore, and therefore how much output the machine can make at a given temperature rise. The exact finished weight and outline drawing depend on the winding and the coupling, so they are confirmed on the certified datasheet issued with the order. The cooling circuit is direct air cooled, IC01, 0.9 m3/s at 47.2 frame, and the frame is steel frame with cast iron end shields. Single-phase winding. This is a single-phase machine, so the winding is laid out to produce one sinusoid across the output terminals rather than a three-phase set. Single-phase alternators of this size are almost always fitted with a capacitor or a compounded excitation arrangement to hold the voltage steady as the load swings, because the pulsating armature reaction of a single-phase load pulls the terminal voltage around far more than a balanced three-phase load does. The practical consequence for the buyer is that single-phase kVA and three-phase kVA of the same frame are not interchangeable: the single-phase machine is derated for the same iron, and the wiring, the circuit breaker and the cable all have to be sized on the single-phase current, which is roughly 1.7 times the three-phase current for the same kVA at the same voltage. Four-pole build. A four-pole machine turns at 1500 rpm on 50 Hz and 1800 rpm on 60 Hz. That is the standard choice for generator sets from a few tens of kVA up to the low megawatt range, because the lower rotor speed gives a longer bearing life, a quieter fan, a higher subtransient reactance that is easier to coordinate with downstream protection, and a rotor that can carry a substantial damper cage for parallel operation. The trade is weight: a four-pole machine of a given kVA is roughly twice the mass of a two-pole one. Excitation and voltage regulation. The excitation system is SHUNT (R250) standard; AREP (R450 / D510C) or PMG optional, regulated by R250 shunt / R450 AREP / D510C AREP, holding steady-state voltage to +/-0.5%. Leroy Somer builds the LSA around three excitation levels. Plain SHUNT excitation with the R250 regulator is the default and is entirely adequate for a single set carrying a stable load. AREP — the Auxiliary winding, Regulated, Excitation, Protection arrangement, run through the R450 or D510C regulator — adds a separate auxiliary stator winding that keeps the excitation supply independent of the main output voltage, so the machine sustains about 300% of full load current into a short circuit for up to ten seconds. That is what lets a downstream breaker clear a fault selectively. PMG excitation goes one step further with a permanent magnet pilot exciter and is normally specified where the load is heavily non-linear or where the set has to ride through a sustained fault. Mechanical build. The frame is steel frame with cast iron end shields. Bearings are permanently lubricated ball bearings. Mounting is IM 1201 (single bearing, SAE flange + drive discs) or IM 1001 (two bearing, SAE flange + keyed shaft). Maximum overspeed is 2250 rpm, and the machine is rated for 1000 m without derating. The rotor is dynamically balanced to ISO 1940 and IEC 60034-14. The single-bearing arrangement couples through a SAE flange and drive discs, so the alternator rotor is carried partly by the engine flywheel housing; the two-bearing arrangement carries its own shaft extension and takes a conventional coupling. Where it fits. Small standby work: a shop till and lighting circuit, a telecom cabinet, a remote monitoring station, or a single-phase domestic changeover. At this size the alternator is usually the cheapest way to get clean power onto a load that the grid only abandons a few hours a year. On a single-phase machine of 15 kW the practical constraint is usually the downstream protection and the cable, not the alternator itself. Core stack position. The S3 core is stack position 3 of 6 in the LSA family, roughly 50% of the way along the family's lamination length range. It sits between the shorter VS2 and the longer S4. Mid-stack builds are the general-purpose choice. The lamination length is long enough to hold flux density at a moderate level and keep efficiency up at part load, while the machine still fits a standard skid or an ISO 20 ft container footprint without a custom base frame. Where it sits in the range. The LSA family is catalogued from 6.4 kW up to 1680 kW, and this page covers the 15 kW / 18.8 kVA point. The step below it is the LSA 40M5 3-Phase at 14.8 kW, 18.5 kVA. The step above it is the LSA 40S4 1-Phase at 17 kW, 21.2 kVA. If your load sits between two steps, take the higher one and let the engine run at part load rather than pushing the smaller machine to its limit on a hot afternoon. Reading the model code. A Leroy Somer designation is read as the LSA or TAL series, the frame size, and the core stack code (VS, S, M, L or VL plus a stack number). Here that gives LSA 40S3 1-Phase for the model, 40 for the frame, S3 for the core and single for the phase count, so the code on the nameplate and the code on this page match one for one. Quoting the full code rather than just the frame matters on this family, because the same frame number is built in several core lengths and the winding changes with the voltage. Frame position. The LSA range is built on 2 frame sizes — 40, 50 — and the 40 frame is number 1 of them. No other frame in this range carries exactly this rating, so the 40 is the only build at 15 kW and there is no cross-frame decision to make. What the nameplate means once it is wired in. At 15 kW and 18.8 kVA this machine pushes 82 A down each line on a 230 V single-phase supply. That current, not the kVA figure, is what the switchgear and the cable have to survive, so the outgoing breaker should be a 160 A frame device set to trip above 102 A, and the run from the alternator terminals to the first panel should be 35 mm2 copper per phase for a normal 25 to 30 m span. Longer runs, aluminium conductors or tray-installed cable all move that number up, and the volt drop at full load is what decides it in the end. On the mechanical side the prime mover has to deliver about 16.8 kW at the coupling. The usual 1.10 to 1.15 margin over the alternator rating covers the fan, the excitation loss and the governor droop, and it is the reason a 15 kW alternator is normally quoted against a 16.8 kW engine rather than a 15 kW one. Fuel burn follows the electrical load almost linearly in this range. At a realistic 0.29 L per kWh for a modern common-rail set, running this alternator at full rating takes roughly 4 L per hour; at 75 per cent load it drops to about 3 L per hour and at half load to about 2 L per hour, because the fixed losses stay put while the variable ones fall away. Quote the breaker frame, the cable size and the engine rating together with the alternator, because a set that is right on paper and undersized on the cable is the most common way a good alternator gets blamed for a bad installation. Where this rating sits in the frame ladder. Within the 40 frame LSA carries 12 distinct ratings, and this is number 8 of them at 15 kW. The step below is the LSA 40M5 3-Phase at 14.8 kW / 18.5 kVA, 0.2 kW under this one; the step above is the LSA 40S4 1-Phase at 17 kW / 21.2 kVA, 2 kW over it. Every step inside one frame is one more lamination stack length. The shaft, the bearings, the foot pattern, the terminal box and the AVR are the same part across the whole ladder, and only the core length and the winding change. That is why the price gap between two neighbouring steps is small while the gap between the last step of one frame and the first step of the next is large. It also sets the value-engineering rule: dropping one core size inside the frame saves money and axial length but eats the margin to the load, while stepping up one size costs far less than jumping to the next frame and buying a bigger skid, a bigger breaker and a bigger cable with it. Supply. Supplied as a genuine Leroy Somer unit — Nidec Industrial Solutions, built in France. LSA and TAL ranges are built in Europe and carry a European certificate of origin. Each alternator ships with the routine test certificate, the winding connection diagram, and the AVR commissioning sheet. Export packing is seaworthy plywood on a pallet sized to the frame, and the machine is strapped and shrink-wrapped inside it. Tell us the engine make and model, the coupling arrangement (single or two bearing), the voltage and frequency, and whether you need a PMG, and we will confirm the build before it leaves the works.