[KNRO]

Hey folks, we have a 10 meter fully rotating dome structure with a shutter door. The shutter door motor is a 3-phase AC motor (1.6 A, 0.18 kW, 900 RPM) connected to some gearbox which is attached to a pulley system. The pulley system is responsible for opening & closing the shutter door. It was operating since 1986 but malfunctioned a few years ago and now we're trying to bring it back online. The main issue is that the AC motor needs a 480 3-phase power source to operate which means that we cannot rotate the dome if we want to open/close the shutter door, otherwise the power cable will snap.

So under these circumstances, what's the optimal solution? Slip rings are not an option as this is a volunteer effor and we want to minimize costs. Would replacing it with a DC motor + batteries work? Any ideas?

Attachment 247570

[Al_The_Man]

I assume the present system is operating OK, just that you don't have 480v 3ph?
I would seem that it also operated at one rpm rate?
What power do you have, 1pH? 3ph? Why the DC motor option, the present motor could be dual voltage if you have 230v 3ph.
Al.

[KNRO]

The system is working OK, and there is a 480v 3ph source but it is located on the stationary dome base, while the shutter door rotates along with the dome itself. Therefore in order to open/close the shutter door _now_ we have to stop to dome so that the shutter door motor is close to the power socket (we have two, 180 degrees apart) on the dome base and connect the power cable there. We would like to have the option of operating the shutter door without this empilical power cable. The image below illustrates this you see the power cable on the rotating part while the power socket on the stationary part.

[Al_The_Man]

That appears to be a 16pin plug/socket, is there other functions taken through this plug?
Does the dome only rotate 180° or 360° ? If it does could you rig up a cable spool and drum system that are used for running out and re-winding the cable automatically?
Al.

[KNRO]

Thanks Al for the response! There are other functions which are obselete now, only the power is used. The dome can rotate freely 360 degrees any number of turns, there are no limit switches/sensors to limit the number of rotations. A cable spool and drum system would work if it only rotates one rotation, but since it is unlimited and there are no proximity/limit switches of any sort now, it wouldn't work.

[Al_The_Man]

What is a typical cycle time or periods the rotation goes through? Several times/hr or a few times/day?
Al.

[KNRO]

It's few times/day.

[Al_The_Man]

You could replace the motor with a DC motor using such as adapting an automotive winch motor system using a 12v on board battery, but it would either require charging when not in use or replacing on a periodic basis.
Al.

[KNRO]

Al, excellent! I don't think charging it would be a big issue for now. However, I don't know where to begin to select a DC motor, what manufacturer/mode/specs/torque/power ratings...etc would I need to sufficiently replace the existing one? Also, the AC motor rated 900 RPM and its shaft is coupled to a gearbox with unknown ratio would this pose a problem or would controlling the speed of DC motor would be sufficient by itself?

Again, thanks for your insight highly appreciated! :-)

[Al_The_Man]

If you have an automotive supplier in your part of the world, you could check out the electric winch fitted to the front of trucks etc, they usually have gearing and may also have a means of controlling the rpm.
You would need to turn the original motor shaft a number of revs and find out the movement of the output to get the present ratio.
The original motor is not that high in power due to the gearing.
Al.