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Title: Isolation "heater" Post by: W7SOE on July 22, 2009, 12:37:48 PM I have had to use an isolation transformer to debug the K7DYY Sr. as it is referenced to mains.
I planned on powering all my test gear through the transformer in the future. Unfortunately it puts off so much heat that I am hesitant to leave it on all the time. Is this something people live with or do they add a power switch? The transformer is a Hammond 1000KVA model. Rich Title: Re: Isolation "heater" Post by: WA1GFZ on July 22, 2009, 12:42:39 PM or pull the plug. Why make heat in the summer? Be careful floating equipment with EMI filters on the power lines referenced to the chassis. A floating chassis could end up hot and give you a tingle
Title: Re: Isolation "heater" Post by: KF1Z on July 22, 2009, 12:43:34 PM The transformer is a Hammond 1000KVA model. ??? Seems like that would be quite the transformer. Title: Re: Isolation "heater" Post by: WQ9E on July 22, 2009, 12:45:00 PM Rich,
I would definitely switch it off when not in use, a switch on the primary side makes it easy to shut off the item under test plus whatever test gear is connected via the transformer. However, I am surprised that it is generating a lot of heat when not under load. I have a similar 1KVA transformer I bought from surplus sales years ago when they used to show up at some of the area hamfests and it never gets very warm. Hopefully someone else with the same model transformer as yours can provide more input whether the no load heating is normal-you might also email the folks at Hammond and get their input. Rodger WQ9E Title: Re: Isolation "heater" Post by: KD6VXI on July 22, 2009, 01:08:25 PM The transformer is a Hammond 1000KVA model. ??? Seems like that would be quite the transformer. I've a vault xformer, capable of 8KV AC at 12A, CCS. It idles nicely at room temp (which has never really been below 78 or so degrees, it's never gotten that cold when I'm here). Once it starts to warm up, though, it really warms a room up QUICKLY. The xformer I have is about 4 foot, cubed...... Maybe 4.5 feet WxL and 4 feet tall. The entire PS is encased in the shipping pallet and associated carton, which is JUST shy of 6 feet all the way around. --Shane Title: Re: Isolation "heater" Post by: W7SOE on July 22, 2009, 01:17:20 PM [/quote] ??? Seems like that would be quite the transformer. [/quote] How did that "K" get in there? Title: Re: Isolation "heater" Post by: W7SOE on July 22, 2009, 01:18:11 PM I think I will added a switched outlet to the bench for the transformer. Perhaps put a nice big fancy red light on it.
Rich Title: Re: Isolation "heater" Post by: k4kyv on July 22, 2009, 03:00:11 PM or pull the plug. Why make heat in the summer? Be careful floating equipment with EMI filters on the power lines referenced to the chassis. A floating chassis could end up hot and give you a tingle I use an isolation transformer to run my receiver and all my audio stuff. The secondary is mid-tapped to ground, so that the entire 110 volt line is balanced. The maximum jolt you could get from ground would be 55 or 60 volts. This helps reduce hum from ground loops. Mine is rated at only 400 v-a; it is an old Isotap transformer designed for bench work at TV repair shops. It barely gets warm to the touch when idling. I used an external precision tapped inductor to establish the mid-tap to ground. If I could find a large enough transformer that ran with good efficiency and had a built-in precision mid-tap on the secondary, I would run every 110-volt circuit on the entire place that way. Of course, I would have to run the 220-volt circuits directly off the mains, but they are already balanced to ground, right at the pole pig. |