vfd hearing protection

[mark480]

I am a licensed electrician in NJ and I am working in waste water plants installing vfds for 250 hp pumps. the problem is the noise level is horrible we are using ear muffs but the freq. is real bad does any one have a problem with this and how do i get the right protection for my men. I have tinnitus and I care about my guys so I do not want the exposure to have the same effects that I have.

 

[cowboyjwc]

You might try and combine plugs and muffs. I shoot so I tend to buy higher end muffs than the kind you get at the big orange or big blue so I can't hardly hear a thing with them on. Two pair I have are over 25 years old and still work great.

 

[PetrosA]

I found these after a quick Google search.

http://www.elvex.com/HB-5000.htm

http://www.omarksafety.com/category.cfm?acatid=61

You want to match the protection to the frequency of the motors as closely as possible. Any chance you can measure it?

 

[mark480]

ear protec

ear protec

does anyone know the noise level for vfds

 

[mark480]

ear protec

ear protec

thank for the reply , my problem is that we use 30 db muffs and ear plugs but with the westinghouse accutrol vfds the noise stinks .this plant does 35mill gal a day do they have better muff then 30dbs and wear can i find them. The guys that work as maintenance electricians are half deaf thanks

 

[mxslick]

Don't know the specific sound pressure level, but the common carrier frequencies are 4khz and 8khz. If you have access to a Real-time analyzer (ask your favorite audio tech) you can get a reading that way and it'll show all the frequencies that are loudest.

You could scroll through the VFD's settings and find out also if you can safely access the drives.

 

[mark480]

thanks for the help

 

[mark480]

do you ride are is that a picture of your kid

 

[SG-1]

You may have a local audio center ( medical ) that could make custom fitted plugs.

 

[mxslick]

do you ride are is that a picture of your kid

Hi Mark:

Nope that's me, I ride mx despite battles with blood clots and my age (I'm now 47). :grin:

Single with no kids....that I know of.

Back on topic so I don't get in trouble...SG-1 is right, and IIRC those custom plugs aren't terribly expensive...in fact they may even have the equipment you need to analyze the noise to get the right plugs made.

 

[wtucker]

Go to labsafety.com (or similar site) and search for "hearing protection." Pay attention to the noise reduction rating, or "NRR." The higher, the better. I've seen muffs rated up to 29, plugs rated to 33 (if you insert them properly). Subtract 7 from the NRR, and that's how many decibels you can go above the 90 dBA OSHA limit for an 8-hour day.

For example: Plugs at 33 NRR. 33-7=26. 26+90=116 db will sound like less than 90. Doubling up muffs and plugs doesn't double the NRR, it only adds 5. In the above example, plugs AND muffs gives you 33-7+5=31+90=121 dBA will sound like less than 90. 120 dbA is the equivalent of an indoor heavy metal rock concert. A chainsaw's about 110.

 

[Besoeker]

I am a licensed electrician in NJ and I am working in waste water plants installing vfds for 250 hp pumps. the problem is the noise level is horrible we are using ear muffs but the freq. is real bad does any one have a problem with this and how do i get the right protection for my men. I have tinnitus and I care about my guys so I do not want the exposure to have the same effects that I have.

We do a lot of drive systems for pumping stations. From my experience, most of the noise is mechanical motor and pump noise which usually drowns out the switching frequency of the drives.
Maybe the motors in your particular case have a construction or characteristics that make them more susceptible to producing noise at inverter switching frequency.

Anyway, I think the cowboyjwc's suggestion isn't bad.
Combining ear defenders and ear plugs would be a simple thing to try.
The ear defenders I use are Peltor Optime III which give an attenuation of over 40dB at the likely range of inverter switching frequencies.