Switch off one leg of three-phase to slow 2t22 speed up?

[Robert Gift]

The 2t22 speeds up too fast.
I'd like to add weight to the rotors, but would not dare do that even if I could figure out where to add the mass.

Once spinning, if I open one leg of the three-phase, would that slow speed-up without causing any damage to the motor?

Thank you,

[JasonC]

The 2t22 speeds up too fast.
I'd like to add weight to the rotors, but would not dare do that even if I could figure out where to add the mass.

Once spinning, if I open one leg of the three-phase, would that slow speed-up without causing any damage to the motor?

Thank you,

Not a good idea on several levels. If you want a slightly lower speed and torque, the best thing to do is buy a transformer (such as a 208/240 "buck/boost" transformer) and place it between the siren and power supply. But this siren is serving as a true warning device so I'd just leave it be.

[Brendan Ahern]

You will burn the motor out. Even if it is at full speed first, you cannot remove a leg of 3 phase. You will overload the windings causing them to overheat and burn out or melt.

[jmev]

You could use a programmable PWM (pulse width modulated) phase convertor that varies the AC frequency. You will need one that supports a 15HP motor for this siren. You would program the unit's startup slope at a lower rate to meet your sound requirements. Just make sure the destination full-speed running frequency is in the 60 HZ range at full 100% PW so to not overheat the motor when running at full speed and also to achieve the proper tone. Expect to pay around $1500-$1800 for a unit. What is nice is that you can get a PWM for single phase feed!

[CDV777-1]

The 2t22 speeds up too fast.

What do you mean that it speeds up "too fast?"
Why would you want to slow down the start-up of a warning siren
by messing with the phases, wiring etc?
Of all the posts I have seen on this board this is one of the most
puzzling.

[JasonC]

I think we need to buy Robert his own 2T22 so he can:

Block ports, remove horns, slow start-up, add resonant cavities, weigh down rotors, and place underwater.

Lol, I'm just messing with ya Robert!

[Gil]

I think we need to buy Robert his own 2T22 so he can:

Block ports, remove horns, slow start-up, add resonant cavities, weigh down rotors, and place underwater.

Lol, I'm just messing with ya Robert!

ROFL!

[Robert Gift]

I think we need to buy Robert his own 2T22 so he can:
Block ports, remove horns, slow start-up, add resonant cavities, weigh down rotors, and place underwater.

Lol, I'm just messing with ya Robert! :wink:

Hey, I'm all for that!
I'd rather have a small siren with which to experiment.

This is my siren and I am planning to add a resonant cavity. That won't hurt anything and can be undone.

Only 7 of the 22 horns are installed while it is on the mobile home stair landing braced against the sewage plant digester rails. (Sorry my Lieutenant has not e-mailed the photos for your amusement.)
If they weren't so difficult to force into their rectangular receivers and attach to the stator, I would insert blocking plates in all but the 7 cones facing the mobile park.

But then I am kind of afraid to do that for fear the escaping air through the open stator ports may imbalance the rotor compared to the blocked air. I'd hate to risk any damage.

Also I am afraid to try to attach the other cones for fear of dropping any into the digester. I already lost a lock washer which I don't want back!

When placed on the fire station roof, I'll attach all cones and paint Lassie fire engine red with black interior cones.

I know about the PWM phase convertor, but they are so expensive.
Switching off one leg would be elegant and simple.
It should not burn out the other two coils.

Thanks for all the advice. I know that leaving it alone is the wisest.

[Adam Pollak]

Do you have any pictures of the siren yet that you can share on here?

[q2bman]

What if you pulsed the power relay to the siren's motor. I don't know why you'd want to but, pulse the relay and second on and a half of or something. That would sound a bit odd but would slow the wind up.

I think we all deserve a good reason as to why you think she starts to quickly and what slowing the wind up would accomplish.