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Can I slow speed-up of three-phase siren?
My Federal Signal 2t22A air raid siren (now tornado siren) attains peak speed, 3,450 rpm, very quickly.
10 hp, 208-240/480. It is running on 240 V. at a small sewage plant next to my fire station. At 5,300 feet and low humidity, I assume the air does not impose the load on the rotors that it would at lower elevations and higher humidity. If I mount the siren on the fire station roof and size the wire to produce a voltage drop to 200 Volts, would that safely slow the acceleration? Federal Signal states that within 10% of operating voltage is acceptable. Thank you. Robert |
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Why would you need to slow the acceleration? I seriously doubt that sizing the wire to 200 V would: a) be code compliant b) work effectively You can do it with a variable speed drive that has a custom ramp control. If it doesn't try a PLC to generate the ramp control. Be warned that you also may need a speed sensor. Another possibility is to use a soft-starter. |
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Thanks, KISS. The siren would be easier to notice with slightly slower speed-up. If I must supply wire, I might as well make it a less expensive smaller gauge AND supply 190 volts at the siren. Can't afford and would not want a VFD at my VFD. Would 190 Volts rather than 240 Volts cause a slightly slower acceleration? 208 volt is design voltage +/- 10%= 188. |
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In an AC motor frequency really determines speed and not so much voltage. Lower voltage isn't good for the motor long term. A soft-starter would be the best solution. http://www.danfos.info/content/files...controller.pdf Older solutions basically added resistors in the line for a short time for start up. That's another way it can be done. |
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Yes, the 60 Hz determines final rpm, 3,600 - (minus) "slippage"? (What's the term?) I just want it to achieve its peak 3,450 rpm a little more slowly. On Youtube, I have heard other 2t22s and they were slower. But maybe they were single-phase. Someone also put my siren on Youtube. The 2t22A is actually two sirens on a dual-shaft motor. One rotor/stator has 10 ports (openings) and the other 12. At 3,450 rpm it produces musical pitches D5 and F5, a "pure" or "perfect" minor third which creates a B-flat2 Resultant. Standing near the siren holding my ears, I can feel my chest vibrate. |
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