Panel meter DC power supply ratings.

[stevenal]

I've been trying to find a simple single phase digital voltage display to indicate LTC voltage. I would like to power the device from a substation DC supply. I keep finding devices, from manufacturers of utility grade equipment, rated for nominal VDC +/- 10%. This tolerance is below normal float voltages, and way below equilization voltages. What are their intended applications? Any standards that apply? And who knows of a good one with +/- 20% or better tolerance with settable high and low limit contacts?

 

[busbar]

Bitronics/Alstom mentions that their watt/var meters are available with optional ‘single supply that operates from 24, 48, 125 or 250V dc source or 115V ac service’ Perhaps the same power-supply range is available for their 1ø single-function products.

Volt/ammeters are indexed at

http://www.esca.com/content.cfm?content_ID=1880

 

[stevenal]

Scott,

What a terrible web site. You'd think they'd have the new one more complete before tearing down the old one. From their paper catalog, anyway, it doesn't look like they have what I need. It is interesting to note that their universal PS for nominal DC voltages up to 250 specs out up to 280. If you have a 250V battery I guess you float it low and never equalize.

 

[busbar]

Steve, I haven’t used any of their stuff since the "merger" but it seemed to be well engineered and fairly rugged. Hard to tell if Alstom changed the way they do business, but agreed the web site is close to worthless. And the (C37.90) 280-volt rating would make more sense.

 

[stevenal]

I see your reference to C37.90. I guess you can use 120 cells at that voltage and make it work. I don't have as much flexibility at the 48VDC level where I work, and C37.90 seems to take that into account. I'll let Bitronics off the hook, but the others need to shape up.

 

[jghrist]

Electro Industries meters have a ±20% control power requirement. See

http://www.electroind.com/pdf/FSeriesManualRev1_7.pdf

(you might have to register to see this page )

 

[stevenal]

Thanks. Electro is what we used to use for this application. Seems they aren't making the DTVA120 or equivalent any more.
I've pressed a couple of the +/- 10% manufucurers, and they claim their 48VDC units will work fine at equilization voltages of 56 and higher. Why didn't they say so in the first place?