Allertor Rotation Direction

[erik92da]

I know Allertors have a directional chopper, and that the whole siren usually rotates counter-clockwise. I went to see the Niles, MI Allertor yesterday and it turns clockwise. It had a very deep overtone that was really noticeable when it was pointed away from me. It also didnt seem nearly as loud as the old 2001-SRN that was next to my house in Portage.

I would have assumed it was wired wrong, but that youtube vid of the one throwing snow out the top horn also was rotating clockwise.

Is it a single/three phase difference, or what?

[Mantis]

Wierd. I don't pretend to know anything about the mechanical aspect of these things, but it kind of seems like it's connected wrong like you said and the motor is turng backwards.

[holler]

Pretty much all of your ACA rotational sirens (normal sized ones, not P-50's) are supposed to rotate counter clockwise. Most people don't pay attention, but having the rotor turning the right direction will make a large difference in output. When we installed the P-15 in Milan, GA, we quicky found out that it the siren was much louder when rotating counter clockwise. Simply swapped the outer two legs changes the motor direction.

As for the 10 and 15 horsepower single phase ones, you can't make them spin backwards. if you get the leads mixed up at the collector rings it won't start period (been there, done that).

[t-bolt82]

just in case nobody has seen it yet, heres the siren in question from Siren1000T1 on youtube:
http://www.youtube.com/watch?v=Dc7Z9KEj654

[Mantis]

Pretty much all of your ACA rotational sirens (normal sized ones, not P-50's) are supposed to rotate counter clockwise. Most people don't pay attention, but having the rotor turning the right direction will make a large difference in output. When we installed the P-15 in Milan, GA, we quicky found out that it the siren was much louder when rotating counter clockwise. Simply swapped the outer two legs changes the motor direction.

Say, I wonder if that's why that Mobil Directo I filmed was so quiet. That one was turning clockwise.

[erik92da]

So it must be wired wrong, eh? It was still loud, but it didnt seem like 125 db, more like a model 5.

Is it normal for an Allertor to have a T-Bolt blower sound when its facing away, or is that because of the backwards chopper rotation?

[der Papst]

So it must be wired wrong, eh? It was still loud, but it didnt seem like 125 db, more like a model 5.

Is it normal for an Allertor to have a T-Bolt blower sound when its facing away, or is that because of the backwards chopper rotation?

A 3-phase-engine changes the direction if you swap 2 powerlines.

And a radial fan with one or more outputs works very inefficient because it depends on the centrifugal force.
A normal omnidirectional siren uses also an radial fan but since the sides are simply open, the rotating direction is not relevant.
Tests with the siren E57 prove that.

[weasel2htm]

So it must be wired wrong, eh? It was still loud, but it didnt seem like 125 db, more like a model 5.

Is it normal for an Allertor to have a T-Bolt blower sound when its facing away, or is that because of the backwards chopper rotation?

I've noticed and mentioned the bassy sound of Allertors before, I think it's motor vibration getting amplified by the horn, but because the horn is pointed away, along with the main sound, the vibration-stimulated bass sound is easier to hear, as bass is more omni-directional and also what is vibrating off the back of the siren/horn.

Clear as mud, right?

[EL1998P71]

So you went to niles and didn't record?
Can you tell me if they went the full three min's or only 1 min?
For the Power plant sirens they state they only test for 1 min all year except in April, they do a longer test (over 3 min's). And it's unclear if Niles follows that same testing plan.

[erik92da]

So you went to niles and didn't record?
Can you tell me if they went the full three min's or only 1 min?
For the Power plant sirens they state they only test for 1 min all year except in April, they do a longer test (over 3 min's). And it's unclear if Niles follows that same testing plan.

Actually I recently moved to Niles Twp, along the Indiana state line. They tested a full 3 minutes this time as well. I also went last month, but it didnt activate. I could hear at least one of the others if not both, but the Silverbrook Ave one stayed silent. At some point a few weeks ago I noticed it was pointing in a different direction and it was not from the wind blowing, although a 20 mph wind will move it. I think they may have fixed it during that time.

Too bad the other two are in areas where a parked car might seem suspicious.