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Does anyone know definitively how many amps of current the 2500 can deliver before the overload starts tripping.The rating is 16VA, which implies, at 12v, about 1.25 A.
Are there any markings on the breaker? You might be able to find its rating.
Yeah. SB601G1BK I have been digging pretty hard. I finally found out it is a Sylvania "bimetallic thermo protector" (that's what theycalled it). I found a part selection guide here:http://www.ultimheat.com/Museum/section1/1970%20Sylvania%2020111013.pdfFrom what I can divine there, these things are designed to open based on heat AND current. They do not really givecurrent ratings for these devices. Now, I suspect that glass device is tucked in where it is so that it will get heated upby the main power transistor down there, and will open if that transistor starts to overheat, regardless ofthe current draw on the power pack. I suppose that's a nice way to design it, but then again, it wasn't working, and I don't see anybroken mounting or glue that was supposed to hold the glass capsule against the transistor. I was surprised at how hard it was to actually track that down. It needs to be replaced, because it no longer opens,even on a dead short. Something else I was shocked to discover. I added a primary fuse. On a dead short on the track terminals,this thing blew a ONE AMP primary fuse (because the thermal protector never trips anymore).Hmmmm 1 amp... 120v.... loosely speaking, that's 120 watts of power dissipated in the primary of that transformer. This means that without that bimetallic thingy working, that transformer could get reallyhot (remember, it didn't have a primary fuse in there before).I put a 3A fuse in there, and then the primary fuse did not blow with the track terminals shorted. Question:So... it was drawing less than 3A, but more than 1A. Your house breaker will not trip, yet that transformer could become dangerously hot, couldn't it? Is there something I'm missing here? All the more reason I'm glad I added a primary fuse.
" Is that your rationale behind the slo-blo fuse?"Yep, that and inrush current. A transformer has all the component parts asa motor, and like a motor , exhibits a inrush when energized.Al
Well, inrush wasn't the issue here. It didn't blow at turn-on. It would blow when I shorted the secondary.I still don't really understand what happens in the primary's electric field to cause this.Perhaps one of you gents will enlighten me. What I see is that the secondary is designed to provide perhaps 1.5A at 16V. Okay, let's say it is generouslyrated heavier than that to avoid failures, so 2 x 1.5A x 16 = 48 watts.On the primary side, at 120V, we have 48 watts = about 1/2 amp. So how does it blow a 1A fuse?