Why 54.5VDC float voltage in a 48VDC system?

[bk81]

Hi Everyone,

I'm a bit puzzled by this, can anyone explain why a -48V dc power supply has a float voltage of -54.5V?

Is it to account for volt drop?

I know this forum is for pv but it's the only place I think I could get an answer!

Cheers...

 

[telectrix]

probably the 54V is the no load output voltage. generally this is higher than the rated output. volts.

 

[HandySparks]

If this is for telecoms work, it's probably because the supply for this type of equipment included a battery for backup in the event of loss of mains supply. 54V is about the voltage needed to keep 4 conventional lead-acid 12V batteries connected in series on charge.