Yep
-----Original Message-----
From: Ken Hohhof
Sent: Friday, February 19, 2016 4:40 PM
To: [email protected]
Subject: Re: [AFMUG] Scooby Doo Mystery Short Circuit
As someone mentioned, 200SS is a DC protector, you are thinking of 300SS.
-----Original Message-----
From: [email protected]
Sent: Friday, February 19, 2016 4:37 PM
To: [email protected]
Subject: Re: [AFMUG] Scooby Doo Mystery Short Circuit
The reason I got into the surge suppressor business in the first place was
due to the design of that 200SS surge suppressor. Hence, my first product
was the 333SS...
-----Original Message-----
From: George Skorup
Sent: Friday, February 19, 2016 12:30 PM
To: [email protected]
Subject: Re: [AFMUG] Scooby Doo Mystery Short Circuit
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.
