Worksheet for System Power Requirements

For systems in which the system power supply is powered from a 12 VDC supply, use the following table to calculate the number and type of system power supplies required to power the system based on the 12 VDC LocalBus power requirements calculated in the Worksheet for Products Using 12 V LocalBus Power and 24 VDC Bussed Field Power. Remember to not exceed 8 A on the horizontal carrier and 15 A on the vertical carrier and remember to include calculations for redundant system power. Add Subtotal 1 from the Worksheet for Products Using 12 V LocalBus Power and 24 VDC Bussed Field Power and Subtotal 2 from the Worksheet for Products Using Only 24 VDC Power to do the calculation.

Table: System Power Requirements - 12 VDC Input
Product Type	Amps Required for Each Product		Total for Product Type
	12 VDC	24 VDC	12 VDC	24 VDC
System Power Supply (Dual DC/DC) 12 V input Provides 13 Amps @ 12 V (Subtotal 1 /13 A = Quantity)	1.8⁽¹⁾	N/A		N/A
Redundant System Power Supply for either Simplex or Redundant controllers (if applicable)	1.8⁽²⁾			N/A
Add for Subtotal 4		Subtotal 4		N/A
Add Subtotal 1 from Worksheet for Products Using 12 V LocalBus Power and 24 VDC Bussed Field Power.		Subtotal 1
Add Subtotal 2 from Worksheet for Products Using Only 24 VDC Power		Subtotal 2
Add Subtotals 1, 2, and 4 for total 12 and 24 VDC power required.		Grand Total

⁽¹⁾ The current required for I/O cards is included in the calculations in Table N-1 and is transferred from Table N-1 to Table N-4 as Subtotal 1. The system power supply requires 1.8 A from the Bulk 12 VDC Power Supply to provide the power for each controller (one controller assumed for each system power supply.) If on a large system, the current exceeds: the 8 A limit for horizontally mounted systems, the 15 A limit for vertically mounted systems, or the 13 A system power supply limit, use the cable extender and split the 12 VDC as described in Appendix J

⁽²⁾ The system power supply requires 1.8 A from the Bulk 12 VDC Power Supply to provide the power for each controller (one controller assumed for each system power supply.)

Example Calculation for 12 VDC Input

Suppose your calculations from the Worksheet for Products Using 12 V LocalBus Power and 24 VDC Bussed Field Power showed that the total 12 VDC power requires 6.1 A. Calculate the number of power supplies required as follows:

6.1 A/13 A/supply =.47 or 1 system power supply for simplex power and 2 system power supplies for redundant power.

If on a large system, the currents exceeds: the 8 A limit for horizontally mounted systems, the 13 A system power supply limit, or the 15 A limit for vertically mounted systems, use the cable extender and split out the 12 VDC as described in "System Power Guidelines" for horizontal systems and "DeltaV Vertical Carriers" for vertical systems.

Worksheet for System Power Requirements - 12 VDC Input

Example Calculation for 12 VDC Input