Author Topic: Suggestions for an isolation transformer  (Read 5492 times)

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Offline Cliff Matthews

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Re: Suggestions for an isolation transformer
« Reply #100 on: April 06, 2019, 07:16:41 pm »
Yup that's a thermal fuse (commonly known as a TCO or 'thermal cut-off). It will be wired on the mains side, since the 4.5 amp overload breaker seems to be on the secondary side.

« Last Edit: April 06, 2019, 07:26:33 pm by Cliff Matthews »
 
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Offline Spork Schivago

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Re: Suggestions for an isolation transformer
« Reply #101 on: April 07, 2019, 08:27:01 pm »
Quote
"Wouldn't I need two circuit breakers?   I was thinking one like this:

Make sure if you use breakers they are rated for the proper voltage. The rating on the one you showed is 32VDC for auto/RV use.

Also think about how long an overload will take to trip the breaker. Thermal type breakers like the one shown in the link or on most power strips can take some time with a moderate overload to trip. If you've ever used an electric space heater on a power strip, you may have had it trip after several minutes, then you had to wait a few minutes for it to cool down so it can be reset.

A fast acting fuse or a thermo magnetic trip breaker might be better.

https://thegrid.rexel.com/en-us/knowledge/product-faqs/w/wiki/323/how-circuit-breakers-combine-thermal-and-magnetic-protection

Thanks for that info!   Yes, I was worried about how long it'd take to trip.   I like the idea of a thermo magnetic trip breaker.   There's currently fast acting fuses in there on the primary side.   The ones I linked to I believe are rated for 32VDC or 125VAC, aren't they?   That's the way I read them.
 

Offline Spork Schivago

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Re: Suggestions for an isolation transformer
« Reply #102 on: April 07, 2019, 08:28:50 pm »
I can only upload 2MB of pictures at one time, so this will be in multiple posts.

You could reduce the pixel size and file size as a consideration to those of us with slow connections. There is no need to post such huge sizes.

Yeah, I was using some free on-line jpeg compression utility, but it was only cutting the size in half, or a little bit more, enough to allow me to upload them.   Then I downloaded IrfanView and I'm just using that now.   I think it's much better anyways.   I had forgotten that IrfanView could reduce sizes until a member mentioned it.   Otherwise I would have used that from the beginning.   I will try to keep them small, especially for people with slower connections.
 

Offline Spork Schivago

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Re: Suggestions for an isolation transformer
« Reply #103 on: April 08, 2019, 06:37:01 pm »
Here's the specs for my Craftsman 82357 DMM, just in case anyone wants them:

Code: [Select]
Basic Accuracy DC voltage 400mV - 1000V ±(0.1% of reading)
AC voltage 4V - 700V ±(1.0% of reading)
DC current 400µA - 20A (fused) ±(1.2% of reading)
AC current 400µA - 20A (fused) ±(1.5% of reading)
Resistance 400½ - 40M½ ±(0.5% of reading)
Capacitance 100nF - 100µF ±(2.0% of reading)
Temperature 0 to 1999°F / -20°C to 1370°C ±(3.0% of reading)
Frequency 500mHz - 10MHz ±(0.1% of reading)
Duty Cycle 0.1 to 99.9%
« Last Edit: April 08, 2019, 06:41:44 pm by Spork Schivago »
 

Offline Cliff Matthews

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Re: Suggestions for an isolation transformer
« Reply #104 on: April 08, 2019, 09:31:04 pm »
Another as the site says, "rescued from the dustbin of history" if it works, don't fix it..  ;D  Site says the meter was made for Sears by Wens Precision Company and it seems their DMMs are all portable data loggers now. Interesting, never heard of them.. but it seems 5-years ago they were sold in AU. 
 

Offline SoundTech-LG

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Re: Suggestions for an isolation transformer
« Reply #105 on: April 10, 2019, 05:02:43 am »
Ok, finally got around to popping the top off of this beast again. The other photo is the Buck wired autoformer to drop my 240 Volt service down to roughly 208 Volts for this 5KVA server room step down isolation Xformer. It has a surge suppressing delay ckt. in it, and 2 fans to keep it cool. Overkill.
 

Offline Spork Schivago

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Re: Suggestions for an isolation transformer
« Reply #106 on: April 10, 2019, 05:33:36 pm »
Should I add a fan to keep my isolation transformer cool?
 

Offline Cliff Matthews

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Re: Suggestions for an isolation transformer
« Reply #107 on: April 10, 2019, 06:14:47 pm »
If not used 24/7, I'd vote no. It's UL approved, has large aluminum case, full-load is rare, it's ~90% efficient, fans irritate, the list goes on..
 
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Offline Spork Schivago

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Re: Suggestions for an isolation transformer
« Reply #108 on: April 15, 2019, 04:53:09 pm »
I think we're done with this thread then.   Thanks for all the help!   Gonna save some cash and order those C14 to NEMA 5-20R adapters.   They where a bit hard to find.   I could find the NEMA 5-15Rs all over the place, but the NEMA 5-20Rs are harder to find.   I only found one company who makes them.

https://www.stayonline.com/power-cords/iec-320-c14-plug-adapters-9958.asp

10$ each, and I want 11 of them.   9 for the transformer, 2 for my PDU to plug in my ONT and MoCA adapter.   I have business class internet for my datacenter, however, I feel the hardware my ISP has provided is more residential than business.   I do have the option of having a dedicated fibre line ran directly to my router but that is extremely expensive.   Hopefully, if my business takes off, I'll be able to afford that sometime.   That's not related to this thread through.   Thanks everyone for all the help and suggestions!!!!!   I understand a lot more now than I did when I started.
 

Online Ian.M

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Re: Suggestions for an isolation transformer
« Reply #109 on: April 15, 2019, 05:16:26 pm »
An IEC C14 plug is only rated for 10A (15A intermittent duty in North America), so you only need a couple of those C14 to NEMA 5-20R adapters for bench use so you don't have to change out NEMA 5-20P plugs on equipment under test.  Everywhere else you need an IEC C14 to NEMA 6-??R adapter for  permanant use the equipment  should *NOT* have a  NEMA 5-20P plug (if it has, its probably going to overload the C14 plug), so you can use the cheap and readily available the IEC C14 to NEMA 5-15R adapters.
 


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