ECP32-3L/4 - Mecc Alte | 65 kW

Model. The ECP32-3L/4 is a Mecc Alte ECP32 4-pole alternator. Mecc Alte reads the model as series ECP32, frame 32 and winding 3L. The trailing 4 is the pole count. Within a frame the winding letter S, M or L sets the stack length, so S is the shortest core and L the longest. It is wound for three-phase service at 50 Hz. Electrical rating. At 0.8 power factor lagging this machine is rated 65 kW, which is 81.2 kVA, delivered as three-phase at 400 V 50 Hz. At 400 V line-to-line that is 117.3 A per line. 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. As built, this machine weighs 480 kg (B3/B14 form), inertia J = 0.24 kgm2. The cooling circuit is direct air cooled; 72 dB(A) @ 1 m, 58 dB(A) @ 7 m at 4-pole 50 Hz, and the frame is steel frame, aluminium or cast iron end shields, C45 steel shaft. Three-phase winding. This is a three-phase machine with a 12 re-connectable winding brought out to 12 re-connectable terminals, so it can be reconnected on site for the usual voltage pairs — 380/220 V, 400/230 V, 415/240 V, 440/254 V and 480/277 V on the 50 Hz build, and the 60 Hz pairs on the 60 Hz build. Reconnection is done on the link board inside the terminal box, not by rewinding, which is why one machine can serve a 380 V job and a 480 V job. The 2/3 pitch, skewed stator slots design is what keeps the fifth and seventh space harmonics down without skewing the stator, and it is the reason the line-to-line waveform stays within the distortion limits the standards ask for. 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 self-excited, brushless, rotating armature with damping cage, regulated by M2K / DER1, holding steady-state voltage to +/-1.0%. Mecc Alte uses the M2K or DER1 regulator on this frame, fed from an auxiliary winding in the stator. The machine is self-excited and brushless, with the armature rotating and a damping cage on the rotor, so there are no slip rings and no brushes to service. The stator slots are skewed and the winding is short pitched, which is how the waveform is kept clean without an oversized frame. Mechanical build. The frame is steel frame, aluminium or cast iron end shields, C45 steel shaft. Bearings are permanently lubricated sealed ball bearings. Mounting is single or two bearing, SAE flange adaptable. Maximum overspeed is 2250 rpm (4500 rpm for 2-pole), and the machine is rated for 0-1000 m. The shaft is C45 carbon steel, the end shields are aluminium or cast iron depending on frame, and the fan is splined to the shaft rather than keyed. Impregnation is polyester resin on the rotating parts and a vacuum process on the stator. The radial force the frame is designed to take is about 5,200 N on this size. Where it fits. Commercial buildings and small industrial plants: office air conditioning, refrigeration, lifts, and a workshop full of induction motors. Motor starting is normally the sizing case rather than steady-state kW. On a three-phase machine of 65 kW the practical constraint is usually the downstream protection and the cable, not the alternator itself. Core stack position. The 3L core is stack position 5 of 5 in the ECP32 family, roughly 100% of the way along the family's lamination length range. It is the longest stack the ECP32 family is built with. Long-stack builds carry the rating in the frame with the lowest flux density of the family. The extra iron costs length and weight, and buys a cooler-running core, lower magnetising current, better part-load efficiency and more margin for site ambient above 40 C or for a non-standard voltage. Where it sits in the range. The ECP32 family is catalogued from 31 kW up to 56 kW, and this page covers the 65 kW / 81.2 kVA point. The step below it is the ECP32-2M/4 at 56 kW, 70 kVA. It is the largest build in the family, so it is the one to quote when the load is fixed and there is no room for a second frame size. Reading the model code. A Mecc Alte designation is read as the ECP or NPE series, a frame digit, a stack letter (S, M or L), and a winding number. Here that gives ECP32-3L/4 for the model, 32 for the frame, 3L for the core and three 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 ECP32 range is built on 1 frame sizes — 32 — and the 32 frame is number 1 of them. No other frame in this range carries exactly this rating, so the 32 is the only build at 65 kW and there is no cross-frame decision to make. What the nameplate means once it is wired in. At 65 kW and 81.2 kVA this machine pushes 117 A down each line on a 400 V three-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 147 A, and the run from the alternator terminals to the first panel should be 50 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 72.8 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 65 kW alternator is normally quoted against a 72.8 kW engine rather than a 65 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 19 L per hour; at 75 per cent load it drops to about 15 L per hour and at half load to about 10 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 32 frame ECP32 carries 5 distinct ratings, and this is number 5 of them at 65 kW. This is the largest rating the 32 frame carries; the step below is the ECP32-2M/4 at 56 kW / 70 kVA, 9 kW under this one. Anything bigger moves to the next frame size up. 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 Mecc Alte unit — Mecc Alte S.p.A., built in Italy. ECP and NPE ranges are built in Italy. 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.