Batboard

I need to know if the Motorola Quantar Power Supply part number CPN1031 is intended for use with +48 Vcd or -48 Vcd!!!

Good question. I would have said -48 vDC. I looked at the instruction manual (not the service manual), and the specifications stated input of +43.2 Vdc to +62.4 Vdc, but a few pages later the block diagram shows "DC input -40 to -60 vdc".

I wonder if it's an isolated (ungrounded) input so it can work in either a negetive or positive ground enviroment.

All 48VDC plant is positve earth - but I don't know about Quantar DC PSU input arrangments.

Astro Spectra wrote:All 48VDC plant is positve earth -

Not all. We have 2 positive 48 volt systems here.

RFguy wrote: I wonder if it's an isolated (ungrounded) input so it can work in either a negetive or positive ground enviroment.

I think the input DC is isolated from chassis ground. Check the DC inputs with an ohm meter to the chassis. I know there is a DC input filter, and reverse polarity diode on the DC input after the circuit breaker/on-off switch.

DC IN FILTER - on-off switch -rev diode

RFguy - that must really limit your choice in rectifiers?

RFguy wrote:Good question. I would have said -48 vDC. I looked at the instruction manual (not the service manual), and the specifications stated input of +43.2 Vdc to +62.4 Vdc, but a few pages later the block diagram shows "DC input -40 to -60 vdc".

I wonder if it's an isolated (ungrounded) input so it can work in either a negetive or positive ground enviroment.

Yes! That´s why I got so confused

Astro Spectra wrote:RFguy - that must really limit your choice in rectifiers?

Yes it is, we have Power Supplies that operate at +24 Vdc and 120 Vac but we do have as well 48 Vdc systems, it´s for this case in particular that I was trying to confirm the polarity of the connection for the power supply because we have +48 Vcd and -48Vcd systems