Technical FAQs

# ION 7550/7650 Digital Input: Internal Excitation DC source power rating

Issue
Customer is looking for the
integrated digital inputs (S1-S8) internal excitation DC source's power rating for the PowerLogic ION7550 and ION7650 meter. This data is not found in the meter's datasheet.

Product Line
PowerLogic ION7550 and ION7650 series power meter

Environment

Cause

A customer may require the internal excitation DC source power rating of the ION7550 and ION7650 meter to be incorporated in technical design data.

Resolution

V = I*R
I = V/R = 30V DC / 220kohm = 1.36 *10^-4 A
P = I*VP= (1.36 *10^-4)*30V DC = 0.00409 W ~ 4.09 mW

As there are 8 digital inputs within the ION 7650 meter, they will draw an approximate maximum of 32.72 mW.

The internal voltage source is isolated from everything else, so it can only be used to switch the 8 digital inputs. The DC power source cannot physically power any other components. As the digital inputs each incorporate a high impedence (220k ohm), the maximum power draw on the internal source will only be about 4mW per input, or 32mW total. That said, the DC source component is rated at 1W.