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33 Range Electric Motors

MOTOR TYPES FOR HVACR APPLICATIONS.

SHADED POLE MOTORS:
Remco’s 33 range of Shaded Pole and Permanent Split Capacitor motors is particularly suitable for driving small and light power fan applications.

They are produced both in 2, 4 and 6 pole versions with outputs ranging from 3 to 100 watts. Generally the range is of single speed motors but there are available some multi-speed motors with 2 speeds. These are marked with the symbol /2 in the motor identification code in the catalogue.

33 range shaded pole and PSC motors are suitable for a wide range of fan applications, both axial and centrifugal types. They are available both in Ventilated and Totally Enclosed bodies and may have single or double shaft extensions. The self-aligning, lubricated for life bearings, in general use on 33 range motors, are designed to provide the quiet running required by many fan applications. (Some PSC motors for higher power and special applications however, are built with ball bearings.)

It must be remembered though that Shaded Pole Motors are not suitable for all types of duty. They are the simplest of the various single phase motor types, rugged and easy to manufacture.
However, the rotating magnetic field required to provide starting torque and fixed direction of rotation is produced not by a separate start winding, but by a single, permanently short circuited band of copper, the shading ring, fitted to the tip of each pole of the motor. Whilst this is simple, and conveniently, does not require either start switch or capacitors, it has two performance effects which limit the applications to which it is suited.

Firstly, the rotating field produced by the shading ring is relatively small, so a feature of all Shaded Pole motors is that start torque is quite low. This is ideal for small, lightweight fans, but insufficient for driving larger and heavier loads, perhaps with greater inertia to overcome.

Secondly, the short circuited shading ring is in circuit whenever the motor is running and produces an appreciable power loss. This power loss is in the form of heat and cooling air is therefore required to dissipate the heat so generated. This is usually achieved by making the motor with ventilated construction, adding a small external cooling fan, or in the case of air moving motors, by situating the motor in the airstream of the fan. Motors are frequently referred to as being “airstream” rated, and these should not be run without cooling air, otherwise they will quickly overheat.

Largely due to the losses caused by the shading ring, all shaded pole motors tend to have low efficiency, (25% is quite typical), and because the shading ring power loss is higher in larger output motors, the power output ratings of Remco 33 range motors are generally limited to levels below 40 watts.

Permanent Split Capacitor motors run with higher efficiencies and may also be built as reversible motors. These are clearly marked in the catalogue.

Ask our Technical Department if you are not sure which style of motor is suitable for your application – they will be pleased to advise you.