On Mon, 04 Apr 2005 09:12:22 GMT, wrote:

Adrian Brentnall adrian-the papers and the wrote:
The problem I'm experiencing is that, when connected to the mains, the
unit happily charges the dryfit battery, but does not 'invert' (i.e.
produce the 48v) when the mains is disconnected. I'm guessing that the
control circuitry is sensing the mains dropping out (as the 'mains'
led goes out) - but the unit doesn't seem to want to go into 'invert'
mode.

HI Matt

Thanks for the reply..

Have you tried putting a small load (5 watts, maybe) on the output?
Perhaps it doesn't switch on if it doesn't detect any connected
equipment. If that doesn't do it, try a little more load, but at a
guess, it should work with half its rated load (18 watts or so).

Yes - I did wonder about that. ISTR that the switchers in PC PSUs
won't run without a load on the output..... I'll try that & report
back


If it was meant to be used with equipment that was also supplied from
a 48 V battery bank, it might want to see some voltage on its output
before it turns on. The idea being that when everything is working,
the external battery bank is being charged by another charger and the
system voltage is maybe 54 V. When mains power fails, the other charger
quits, and the external battery drops to maybe 50 V. As it discharges,
maybe to 46 V, this UPS detects it and kicks on to supply power. If
the voltage gets too low, it might shut off automatically.

Hmmm - I'm not sure about that. I think ths box is certainly from the
telecomms field, but I'm guessing that the -48v is intended to replace
the usual line voltage from the exchange.... but I'm guessing.


There's a multi-way connector strip on the outside of the case - which
has connections for 48v, plus a number of status connections - but I
have no documentation on these.

Are there any labels on the strip? If so, what are they?

Now that'd be far too easy g. Actually - they are labelled - 1
through to 8 - where 7 is also a black label and 8 is also a red label
- so it looks as if they might well be the -48V connections.


Since this sounds like phone gear, you might also ask over in
comp.dcom.telecom.tech .

That's a good idea - I'll go there in a day or too and see what they
have to say on the matter.

Many thanks Matt

Adrian
Suffolk UK
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