The latest model is 200SSH. These were bought new (or allegedly new)
within the past few months.
They haven't discontinued it have they?
On 2/19/2016 3:42 PM, Sean Heskett wrote:
Isn't the 200SS about 10 years old.
I'd replace it with something newer
On Friday, February 19, 2016, Adam Moffett <[email protected]
<mailto:[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.
