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Parked scope power requirements

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#1 lukepower

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Posted 27 December 2013 - 05:55 PM

Hi there,

 

I was wondering how much current the DDM85 (in my case XL) drwas once it has been parked, like during the day. I used to power off everything after the night, but my remote setup is very position-sensitive to avoid collisions with the roll-off roof, so now I am considering to simply leave everything powered on. What would the motors consume? My guess would be that, a properly balanced telescope should need very little force and so very little power to keep everything fine, or am I wrong here?

 

Thanks

 


Lukas Demetz
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www.skygemsobservatories.com
Astro Dolomites Observatory, Skygems Network
Santa Cristina Valgardena, Italy
20" Cassegrain-Newton on ASA DDM85XL


#2 nakbrooks

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Posted 27 December 2013 - 07:11 PM

When you say powered on, do you mean power on but motors off or power on and motors also on.

With motors off I would imagine it would consume next to no power. I would be wary of leaving the motors permanently on, although as my scope is well balanced in a closed dome the motors should be doing no work so maybe that is just my natural caution.
Nigel Brooks
Stratis Observatory, Hautes Pyrénées, France.
http://www.facebook.com/stratisobservatory

#3 lukepower

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Posted 27 December 2013 - 08:40 PM

Hi Nigel,

 

I actually mean power on and motors on, like when you park the scope (but leave the motors on). I am seeking a way to hold the scope there no matter what happens, as I have a mere 6cm of room between the parked scope and the roof. A slight misbalancing, maybe caused by the motion of the focuser, could be enough to ruin my day ;)


Lukas Demetz
------------
www.skygemsobservatories.com
Astro Dolomites Observatory, Skygems Network
Santa Cristina Valgardena, Italy
20" Cassegrain-Newton on ASA DDM85XL


#4 nakbrooks

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Posted 27 December 2013 - 08:51 PM

In theory, if your scope is protected against gusts of wind and is well balanced it shouldn't use much power if left with the motors on.

However personally I would have a major concern that a power surge or software glitch could cause an unexpected large random mount movement that might cause you problems if you have limited clearance. I have an equatorial (XL) pier and a largish dome so have full 360 degree clearance on both axes without hitting anything - but even so I'm not sure I would leave the motors on when not imaging.

Probably best for ASA or someone else more experienced than me to give a definitive opinion though.
Nigel Brooks
Stratis Observatory, Hautes Pyrénées, France.
http://www.facebook.com/stratisobservatory

#5 nakbrooks

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Posted 27 December 2013 - 08:53 PM

As an afterthought, maybe a physical solution might work (e.g. Foam fastened to the inside of the roof where it might contact your equipment)?
Nigel Brooks
Stratis Observatory, Hautes Pyrénées, France.
http://www.facebook.com/stratisobservatory

#6 lukepower

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Posted 27 December 2013 - 10:01 PM

Hi Nigel,

 

I actually have a light reflection sensor to monitor for the correct park position of the telescope. In theory, as soon as I turn off everything, the sensor would inform the roof controller if the telescope is still "Safe" (ie. in its park position) or not. If not, the roof wouldn't open and nothing would be hit. I could also work with foam, but my major concern is if it hits the roof while it is opening or closing (happened once, ruined my concrete base).

 

Regrettably, the observatory building's dimensions have been limited by various factors, including the neighbours :) I had once a dome, but it was simply too small for the new 20" scope :/


Lukas Demetz
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www.skygemsobservatories.com
Astro Dolomites Observatory, Skygems Network
Santa Cristina Valgardena, Italy
20" Cassegrain-Newton on ASA DDM85XL


#7 RamaSpaceShip

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Posted 28 December 2013 - 08:45 AM

Hi Luke,

 

If you put a plastic ceiling to your roof, then you cannot hit when opening as the scope is already below the ceiling and can only slide along this ceiling, and the plastic will not do any dammage. Then the only risk is the edge of the roof when closing. You can put an electric switch on this edge which cuts the power of the roof motor when hit. You can also use a camera to monitor this critical phase. In addition, you can extend the plastic ceiling outside to guide the scope below it, as in case of wrong position, the scope should not be that far and the plastic can have the appropriate shape to put back the scope in the correct place. If the position is too wrong, the plastic will fold without dammage, and this leaves time for the other security mechanisms to activate.

 

I agree with Nigel that I wouldn't leave the motors on. In case of a problem, they create a too big resistance which can lead to dammage. When the motors are off, the scope can move freely and be pushed away in most cases.







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