255-FES72-125 — 9.5 kW 72V PMSM motor

36 Nm continuous at 2,600 RPM · 102 Nm peak · 255 frame

The 255-FES72-125 is a 9.5 kW 72 volt BLDC motor with an unusually wide working range. It holds 36 Nm continuously at 2,600 RPM on 125 Arms, and reaches 102 Nm at 375 Arms — nearly three times continuous, with a peak output of 26.1 kW from a 32 kg frame.

It is the faster half of a winding pair. The 255-FES72-080 produces almost the same torque — 34.5 Nm — but at 1,600 RPM on 80 amps; this winding gives 36 Nm at 2,600 RPM on 125. Sixty per cent more speed and nearly twice the output for half again the current, at the same torque, in the same 32 kg frame with the same rotor. Where the load will accept the speed, this is the more productive of the two; where the controller or the battery sets the ceiling, the -080 is.

Twenty-six kilowatts of peak from a 32 kg machine is the headline number, and it is usable peak: the torque curve is flat from standstill to rated speed at every current up to 250 Arms, so the machine behaves the same whether it is starting, running or riding out an overload. Only the peak curve begins to fall before 2,600 RPM, which is why peak power arrives just below rated speed. Sizing the drive for the average load and letting the motor absorb the peaks is a legitimate strategy here, provided the controller can supply 375 amps in short bursts.

Rotor inertia is 0.008789 kg·m² — enough steadiness to tolerate load that varies through the cycle, without the sluggishness of the heaviest 255 rotors. At 216.6 Hz rated frequency the drive requirement is moderate and should suit most 72 volt controllers.