Warning Siren Catches fire in Aurora......

[12kvLive]

If it is a DC siren November was the first cold weather test for the area. If some of the cells in the battery bank failed, that could have caused a drop in operating voltage. Operating on AC the rectifier charges the batteries and operates the siren. The additional load of a defective couple cells in a batt. bank could have caused a voltage drop. The motor's current could have raised high enough to cause the windings in the motor to burn. Wind is what brought the fire to the front. On a normal day the wind up there is strong. I'm not sure but I do believe the motor housing is metal? If it is, it wouldn't burn and act like a duct to carry fire in the wind. That's my theory.

[Robert Gift]

I still say friction in material in the rotor and stator.

Or does the motor have air cooling passages to the fronthrough which
fire can pass?

How embarrassing the very first operation.

Don't the batteries have a fuse in line with the motor so such over current will be prevented?

[jmev]

If it is a DC siren November was the first cold weather test for the area. If some of the cells in the battery bank failed, that could have caused a drop in operating voltage. Operating on AC the rectifier charges the batteries and operates the siren. The additional load of a defective couple cells in a batt. bank could have caused a voltage drop. The motor's current could have raised high enough to cause the windings in the motor to burn. Wind is what brought the fire to the front. On a normal day the wind up there is strong. I'm not sure but I do believe the motor housing is metal? If it is, it wouldn't burn and act like a duct to carry fire in the wind. That's my theory

Huh?

The motor's current would have risen? I think you mean the motor's current REQUIREMENT would have risen given a definite load and voltage, although actual measured current would not have incresed being there was no available energy. Wattage remains constant on the load regardless.
It is a big misconception that when you get resistance (voltage drop) that a load's current increases. According to Ohm's law, this is true, however in the real world, when resistance (or voltage drop) is introduced to a circuit the current remains constant or many times will DECREASE. For a given load's total energy draw (wattage), when the voltage is decreased, you will need more amperage to keep the wattage load constant, it won't happen.

Don't believe it? Get a motor with a load (or light bulb) and connect it inline with an ammeter ammeter and take a measurement. Now decrease the voltage and watch your ammeter. Clamp an inductive DC ammter on your car's negative battery cable and watch the meter when starting the engine. Now leave you headlights on for 6 hours to run the battery down and create a voltage drop. Take a reading now. When you run the battery this low, you won't start the car, but you also didn't increase the amperage up over your original reading.

When was the last time that you experienced a power "brownout" in your home and all of the Romex wiring smoked and burned up and tripped all of your breakers from the lower supply voltage? That's right- they didn't. The amperage requirement increased for all of the laods in the house, but the actual amperage draw did not. Voltage drop on certain types of AC induction motor variations cause the motor to overheat, but it's not from an excess current draw, but rather than some more technical internal reasons that I'm not going to get into here.

Basic formulas only work for given constants. Don't try to use Ohm's law on a PWM driven motor!

[Federal Signal fan]

Lucky no one was killed. Lucky it didn't fall either, for it could of cause a brush fire. Also, a huge 1/2 siren falling on fire doesn't seem gentle to a by stander. It does seem like some sort of friction caused it. Whatever happened, it caused a fire, the siren DID NOT fall, and no one was hurt. All will be answered once the investigation is complete. Thanks for sharing, and that can't be good for publicity in the area and for American Signal. Hopefully it wasn't a part error, the last thing we and American Signal want is a major nationwide recall! It says it will cost the city about $24,000.00- sirens are definitely something you don't want to waste, or catch on fire.


It seems that the fiberglass is an all around body. I could be a metal rear-end. But I'd ask jkvernon, he's likely to know quite a bit about the T-135's housing. But if something when haywire with the DC current, then the AC current would back-up. Wind does seem to play a factor here, the first picture provided by the article shows the flame and it's smoke at an acute angle. Therefore, it was a likely windy day. At the second picture, it does look like there was some slight inside damage. But it all seems to be featured more on the outward position, but it could have started in the motor/rotor area, and move out quick. But again, I'm not one to know the workings of this siren, so I'd offered my two cents. Use them or not, I've offered them.

EDIT:

All external horns and covers are fiberglass. No painting or eye sore problems over time.

So yes, the covers are fiberglass...

[Brendan Ahern]

Another thing I would like to know is why they got rid of the P-50 that was there. If it didnt fail, then why replace it.

[Jim Z]

Another thing I would like to know is why they got rid of the P-50 that was there. If it didnt fail, then why replace it.

no monitoring and no battery backup.

[jkvernon]

By looking at the photo, the fire appeared to begin at the front of the horn. There's nothing electrical in the horn itself whatsoever, only in the back under the rounded cover. I'm really just assuming it's friction related in the rotor/stator because I can't think of anything else that would cause it in the horn.

As far as what the housing is made of, it's all fiberglass. The motor housing, the inner horn assembly, and the main outer horn are all indeed fiberglass and the rotor stator I believe is aluminum.

[SirenMaster2000]

Now there's two things you don't see everyday(inside of a siren and siren catching fire) I've heard of a hot product but geez.

[ver tum]

You're right, Jmev. I have a variable voltage transformer, which I have an electric fan connected to. When I lower the voltage on the transformer, the fan simply slows down, and the heat in the motor actually decreases. I think that for the most part, AC cap start motors, or motors with separate windings for startup, are negatively effected by a voltage drop, but anyone please feel free to correct me if I'm wrong. When the amps are dropped with a dimmer switch, that's when you can have problems with a lot of AC motors, unless they're especially designed for that, but we're talking about a DC motor, and I don't think that they would be effected by that in a negative way.

[carexpertandy]

LOL!!! It's a T-128