48 volt uninterruptible power supply

[Adrian Brentnall]

HI All

I wonder if anybody out ther has experience with this piece of kit -
or similar.

This unit has a 2-part black metal case enclosing a battery charger /
invertor PCB, with space for Dryfit battery. Fitted with rubber feet
and keyhole slots for wall-mounting.

Specifications

* Input
88 to 275 VAC, 43 - 63 Hz, 0.6 Amps, single phase
* Output
-48v DC, 35 Watts continuous, stored energy time 6 hours,
ambient temperature -10 to +55 centigrade
* Manufactured by L3 Communications - Model no UPS10B00

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.

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.

Would you expect to have to 'do something' (as in wire links on the
multi-way strip) in order to kick the thing into operation ?

Possible thoughts so far
a) Faulty unit - not likely as units were sold as NOS, and the two
units I have behave in excatly the same way
b) Faulty dryfit battery - don't think so - they hold a charge ok -
and terminal voltage remains around the 12v mark after the mains drops
out
c) User error ( ! ) - in that I need to 'do' something more in order
to 'make it happen'

I will be contcting the manufacturer to see if they can shed any light
on the matter - but I wondered if some kind soul out there might have
'been there, done that' already...?

Thanks in advance
Adrian
Suffolk UK
======return email munged=================
take out the papers and the trash to reply

 

[[email protected]]

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.

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).

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.

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?

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

Matt Roberds

 

[Adrian Brentnall]

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.

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
======return email munged=================
take out the papers and the trash to reply

 

[Adrian Brentnall]

Hi Matt

Just to follow up on my earlier post - and in case anybody else is
searching in thre future for the answer to the same question :-

It seems that this UPS wants to see a link between pins 1 and 6 on the
terminal strip. I think this is a kind of 'UPS enable' link - which
prevents the UPS from functioning during shipping.

It also wants to see some kind of a load on the 48v terminals (I used
a 470R / 2W resistor.

If both of thesethings are present, AND mains is applied, then 48v
appears at the output terminals.
Subsequently, if the mains then drops, the unit goes into UPS (battery
backup) mode.

In short, it works ! - but only if the above conditions are satisfied,
and in the right sequence........

cunning, eh ?

Thanks all
Adrian
======return email munged=================
take out the papers and the trash to reply

 

[[email protected]]

It seems that this UPS wants to see a link between pins 1 and 6 on the
terminal strip. I think this is a kind of 'UPS enable' link - which
prevents the UPS from functioning during shipping.

Glad to hear you worked it out! (Did you find documentation, or just
start playing with it?)

I bet if you start playing with a voltmeter or ohmmeter you will find
that some of the other terminals open and close with the mains, and
possibly open and close with a good/discharged battery.

It also wants to see some kind of a load on the 48v terminals (I used
a 470R / 2W resistor.

Did the red and black terminals (1 and 8) turn out to be the 48 V
terminals?

Matt Roberds

 

[Adrian Brentnall]

HI Matt

Glad to hear you worked it out! (Did you find documentation, or just
start playing with it?)

Both !
There's a similar unit on the web at www.powerstream.com/Product2.htm
- and it sort of mentions that there's a need for a link between 1 and
6...

But the sequence of operations turns out to be critical..... which
caused me some confusion (doesn't take a lot, these days !)

I bet if you start playing with a voltmeter or ohmmeter you will find
that some of the other terminals open and close with the mains, and
possibly open and close with a good/discharged battery.

Correct - as per the weblink above

Did the red and black terminals (1 and 8) turn out to be the 48 V
terminals?

7 & 8 - yes. Plenty of 'juice' there - certainly enough to cook the
first resistor I used as a load <g>

Many thanks for your input - it does help to be able to 'bounce' ideas
off another person - my 2 dogs are clueless when it comes to
electronics !

Thanks
Adrian

======return email munged=================
take out the papers and the trash to reply