Hi all,
Are I becoming even more paranoid?
I notice people are starting to mount toroidal transformers directly on metal mounting plates/chassis without using the proper mounting kit. I am concerned that the insulation will wear through resulting in a short to the chassis.
Is this a safety issue?
regards
Are I becoming even more paranoid?
I notice people are starting to mount toroidal transformers directly on metal mounting plates/chassis without using the proper mounting kit. I am concerned that the insulation will wear through resulting in a short to the chassis.
Is this a safety issue?
regards
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It's a wise idea to use neoprene washers to prevent damage to the windings. If the centre of the transformer is potted then you can get away without using them. The washers are only there to protect the windings.
Hi KatieandDad,
Thanks. Personally I always use the neoprene washers, but I am beginning to see people mounting unpotted toroids directly onto metal surfaces. I always cringe but say nothing.
I have noticed that cheap toroids are often supplied without the appropriate mounting kit. These cheap toroids also can have untidy windings that results in a couple of windings becoming the pressure point on the metal mounting surface.
I consider this a major safety issue. What do other's think?
I just want to raise this as a "potential" issue.
regards
Thanks Dale,
Yeah, we always point out the shorted turn issue but I have never seen anyone point out mounting directly on a metal surface without a neoprene washer as being a safety issue.
I have been wondering if I was been "overly" concerned as even our safety experts have not raised the issue (well, I have noticed any warnings).
regards
Squeeze a pecan sized blob of silicone bathtub caulk onto the mounting surface and spread it out into a circle whose diameter is 1cm larger than the diameter of the toroid. Let it dry 24 hours. How thick is it? How springy is it? If you're worried it's insufficient, apply a second coat and let dry another 24 hours. Now your toroidal transformer rests on a pliable, vibration-absorbing cushion of silicone.
Silastic, like solder and cyanoacrylate adhesive and AWG26 insulated wire, is one of the items found on any electronics workbench worthy of the title. I've used it liberally to improve the mechanical integrity of comparatively large components (e.g., capacitors) mounted on a printed wiring board. Using it as a mounting cushion under a toroidal power transformer is a great idea. It may take a little effort to give it a neat and tidy visual appearance but even a sloppy job will perform the functions we're concerned with here.
Other DIY approaches to creating a mounting washer include:
- Cutting a circular washer from a piece of neoprene gasket sheeting, purchased at the auto parts store
- The circular plastic lids found on cans of coffee, salted nuts, margarine, shortening, etc, at the grocery store
- Circles cut from scrap pieces of short-nap indoor/outdoor carpet (the kind with flexible plastic, rather than foam, backing)
A nut with the plastic locking insert (see http://en.wikipedia.org/wiki/Nyloc_nut ) is, in my mind, a more elegant approach.
Dale
The primary is wound on the inside. So the worst case would be a secondary short. If properly fused the the fuse will blow. Only a life safety issue if there is a fire.
Thanks for the tip... and, no I haven't yet - I'm still building the Pre-Amp 😉
Dave.
Not always
I reported a toroid with inside out windings a few years ago.
It surprised me, but not so some other Members.
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