VFD on an Air Raid Siren?

[zw17]

I have a buddy who is a volunteer firefighter, his department is looking to get rid of a old air raid siren that they sound anytime there is a fire call, it's kind of a tradition in volunteer FD's. They claim it costs too much to sound the thing. I suppose they are looking to "go green" with a electronic speaker siren.

I suggested putting a VFD on it to help with the cost but the more I think about it it may end up distorting the sound only running at say 75% of speed and once you go to 100% you aren't really saving much.

What says the hive?

Video of a like siren.

[viceman]

i dont know if it would work but i would love to try it!

[henpeck]

Sounds like a York air cooled chiller. Screw compressors on a drive that run up to 200 hertz

[jburchstead]

I am aware of a situation like this, however it was the fact that it was a three phase motor and it was the minimum power company charge that was costing them so much and not the actual usage.

[zw17]

I am aware of a situation like this, however it was the fact that it was a three phase motor and it was the minimum power company charge that was costing them so much and not the actual usage.

Ahhh... I never tonight of that. I am not sure if that is the issue or not?

[henpeck]

Could you use single phase power and install a VSD and use it to create your 3 phase power source??? To avoid power charges?

[hotrodrob]

Could you use single phase power and install a VSD and use it to create your 3 phase power source??? To avoid power charges?

Yes you can use a VFD on single phase to create 3 phase. I think the ABB guidline is at least a 50% derate. so if you have a 5 hp motor you would need a 10hp drive for it to work.

[flange]

check with your utility to see if you can get a rebate for installing the vfd, lol.

[maintenanceguy]

If it draws 100 amps at 240V for 3 minutes, that's 1.2KWH for each fire. at $.13 a KWH, that's about 16 cents for each fire.

I think the fire sirens are a nuisance now that we have other ways to communicate but if the FD doesn't mind annoying the neighbors in the name of tradition, run the siren they have.

[swei]

Yes you can use a VFD on single phase to create 3 phase. I think the ABB guidline is at least a 50% derate

Just be sure there's no hard-wired phase failure shutdown in the VFD firmware. Most anything 3HP or less comes equipped for single phase input (rectifier diodes rated for at least 1.73x input current, no phase failure shutdown.) Gets a little tougher at 5HP - the Hitachi's we used to use were discontinued a couple years back.