Stepper motor used for rotating beacon warning light?

[Tunelabguy]

I understand a bipolar stepper has two coils only

No, it has two phases. Each of those phases is composed of multiple coils wired in series. Each coil is wound around a pole. The number of poles determines the number of steps per revolution. Although it is possible to make a stepper motor with only one full step per revolution, you don't get very much torque that way.

 

[BradtheRad]

Thanks, though with the beacon possibly being on for 20 hours per day, every day, won't the brushed dc suffer too
much wear of the brushes?

This brings to mind the geared motors that are in old-fashioned clocks. Millions installed. Low power. Not too large. 24/7 continuous use. Lifetime measured in decades.

It's an AC motor, so it has no brushes.

A similar motor might be in disco-ball spinners.

The gears bring rotation down to 1 rpm. The video looks as though the beacon rotates about 60 rpm. It might not be easy to get a gearbox that does this.

Moreover you would need to chop a DC supply into AC.

 

[ahsan_i_h]

This type of beacon uses stepper motor.
https://www.aps-supply.com/e-Catalogue/id/30/prod_id/905/

 

[dick_freebird]

Stepper motors are usually manufactured with more precision
in mind, than a simple universal or PM brushed motor. The
application does not value precision, only durability and cost.
A stepper motor incurs the added cost of a driver board, to
no real benefit.

 

[ahsan_i_h]

As beacons are used in warning purpose, so reliability is more important than durability. The link from post #23 also explained about reliability. To get better reliable operation, extra cost of driver board sometimes may be tolerable.