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In Reply to: RE: Isolation transformer in use info posted by dcuhl on February 02, 2017 at 15:22:46
Everything sounds fine to me. Why any DC offset on the mains would have any effect on the Topaz EI transformer beats me. You might check to make sure the end bells are securely tight on the transformer.
The only thing I can tell you is to either buy a DC blocker or build one yourself. If you build one make it big enough so you can try it on the Hair Dryer. Some of those dryers are 1500 watts. (1500 / 120V = 12.5 amps)
The only other thing I can think of is to buy a different brand/manufacture hair dryer for the wife.
One other thing that comes to mind you could try, check out, is to see if the topaz transformer and hair dryer receptacle are fed from the same Line, leg, in the electrical panel. If on the same Line, leg, try putting the hair dryer receptacle on the other Line, leg, or your dedicated 20 amp circuit for your audio on the other.
You never did say where the hair is used now and what the branch circuit size is, 15 or 20 amp. Is the circuit shared with other loads?
Sorry for the delay in responding, my 20 year old daughter is having some health issues. The isolation transformer consists of 3 major parts, the front and rear 3rd's are identical cast aluminum housings with different end plates, one with the AC cord the other with a single duplex outlet, no fuse and no power switch. the middle third is the transformer itself. 3 through bolts, two on top, one center bottom hold the 3rds together. So in reference to the bells perhaps being loose and possibly causing the hum, there really aren't any bells as one would think of them. The topaz uses the cast aluminum housings as the bells, the insides of which are empty or hollow with nothing to block the transformer radiated emi from reaching the incoming AC current or from it reaching the back side of the duplex and its AC connections. What to do in this space to shield, block or absorb the emi has been the subject my mind ponders, whenever it has a free moment.
The blow dryer could be in a 15 or 20 amp circuit as the most likely breakers are adjacent and it could logically be on one of three and the only real way to find out is to intentionally trip it to find the specific one rather than flipping breakers and having to reset or reprogram various kitchen devices, which I am unwilling to do. As to which leg, again I'd have to trip the breaker to know for certain. Perhaps the next time the power goes off and I have to reset the appliances anyway I'll take the 3 minutes to figure it out. To all whom responded, many thanks for your help and input, it is appreciated.
Sorry to hear about your daughter. I hope she is doing better.
3 through bolts, two on top, one center bottom hold the 3rds together.
Make sure the 3 through bolts are tight. It is possible the steel laminations of the EI transformer may not securely be tight against one another. Like I said in an earlier post it is unusual for an EI transformer to physically vibrate from DC on the AC mains.
The blow dryer could be in a 15 or 20 amp circuit as the most likely breakers are adjacent and it could logically be on one of three and the only real way to find out is to intentionally trip it to find the specific one rather than flipping breakers and having to reset or reprogram various kitchen devices, which I am unwilling to do.
Danger! Never intentionally attempt to trip a circuit breaker. IT may not trip open.
Believe it or not when UL tests a circuit breaker they only test the breaker twice to see if it trips open. Scary ain't it?
You can buy circuit checkers fairly cheap that will locate the breaker that feeds the branch circuit wiring. Below is a link for an example.
Looks like there was some pruning done in this thread. I think if you are going for efficiency, there won't be an air gap, and the laminations supply a complete circuit. Of course, if the cores are designed to handle DC, there will need to be a gap to prevent saturation, same as with toroids that have a gap cut when used for choke applications.
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