Isn't the 200SS about 10 years old. I'd replace it with something newer
On Friday, February 19, 2016, Adam Moffett <[email protected]> wrote: > I would have assumed they weren't supposed to short the + and - wires when > clamped. That would be the opposite of protection lol. I also don't get > why the short to stay there with the power shut off. I spent a good 15-20 > minutes checking things with the power shut off, and the short didn't go > away until I disconnected and reconnected wires on the SS. I would have > guessed the clamping would stop when the over current or over voltage > condition went away. > > I did eventually find literature saying that the 200SS can take up to > 6.5amps. This BS uses 90 watts on bootup, and maybe 60 watts in normal > operation. The spec sheet says 125 Watt max. So somewhere from 1.5 to 2.5 > amps. > > Maybe that particular SS is just broken in some way? If so, it's a > dangerous mode of failure. > > On 2/19/2016 2:30 PM, George Skorup wrote: > >> Definitely sounds like the SS was clamping. Maybe the SS thought a surge >> occurred at initial startup of the power supply? And FYI, I have used Traco >> TSP 48v supplies with -48 radios just fine, output is floating. >> >> On 2/19/2016 10:40 AM, Adam Moffett wrote: >> >>> ...my first thought of course was maybe it was hooked up wrong the first >>> time. The four 16ga wires hold their shape pretty well and I didn't have >>> to re-bend them to fit, so I'm pretty sure they were on there correctly. >>> >>> People talk about SS's "clamping" or "clamping to ground". Could that >>> cause a short? I never tested the power wires against ground. >>> >>> If you're thinking +48 and -48 mixed on the tower, there are only two >>> devices on the tower right now. One base station and one backhaul, and >>> they're both -48. There's some 24v stuff in the enclosure at the bottom >>> (switch, site monitor), but none of those have a ground referenced to power >>> and they're isolated from the other stuff by a 48v to 24v converter. >>> >>> >>> On 2/19/2016 11:27 AM, Adam Moffett wrote: >>> >>>> So I went out to a new location yesterday afternoon just to turn the >>>> breakers on. The power co had just plugged in the meter a few days prior. >>>> >>>> The Traco 48v power supply there immediately went into an alarm state. >>>> After some troubleshooting I found a dead short on the -48v power bus >>>> (terminal blocks with jumpers actually). The short ended up being on the >>>> power cable to a Wimax base station, I read 0 ohms between + and - on that >>>> cable. >>>> >>>> There's a Motorola 200SS surge suppressor within 5' of the power bus, >>>> and then about 80' of wire to the base station. I checked resistance >>>> between + and - on each side of the SS and read 0 ohms both ways. There >>>> are actually 4x 16ga wires going to the top, so two were screwed down to + >>>> on the load side of the SS and two on the - side. >>>> >>>> That whole part was backstory. This is where the mystery starts. >>>> >>>> I pulled all 4 wires off the load side of the SS to see if I could >>>> narrow down which pair was shorted, and I couldn't find a short. I checked >>>> the load side and the supply side of the SS and it was open on both sides. >>>> So then I reconnected the wires to the SS and checked again - no short. I >>>> plugged the BTS back into the bus...powered up just fine. >>>> >>>> So where did the short circuit come from and where did it go? In >>>> hindsight it seems like it had to be in the SS or before it. If it was >>>> shorted at the top there would have been > 0 ohms of resistance with the >>>> 80' of wire. >>>> >>>> >>>> >>> >> >
