Tema Stainless Steel SS90L-4

With a rated output of 1.5 kilowatts, the motor is among the smaller series types, driving small centrifugal pumps, dosing systems or stirrers. Stainless-steel housings markedly improve resistance to cleaning agents, moisture and aggressive media compared with painted cast iron, though they add weight for the same frame size.

In industrial motors of this kind the squirrel-cage rotor is standard, since it runs with little maintenance and needs no slip rings. The number of poles sets the synchronous speed: at 50 hertz, two-pole motors turn at 3,000 revolutions per minute, four-pole motors at 1,500 and six-pole motors at 1,000, each slightly reduced by slip. Protection ratings follow IEC 60529 and mounting arrangements IEC 60034-7, for example a foot-mounted IM B3 motor or a flange-mounted IM B5 type. Running it from a frequency inverter raises the demands on insulation strength.

When buying such a stainless-steel motor secondhand, the rating plate is worth checking first, along with whether output, voltage and frequency match the intended installation. Turning the shaft by hand shows whether the bearings run smoothly, without play, while an insulation test reveals damp or damaged windings, which frequent washdown encourages. Seals at the shaft lead-through and terminal box deserve a further look, since leaks are a common cause of failure in stainless motors used in wet areas.