Alpha Technologies DCP03 300A - Manual (Page 16)

020-702-C0 Rev C WC Page 10 of 16
5 Wiring
This chapter provides cabling details and notes on cable sizing for DC applications with respect to the product.
WARNING
Ensure that power is removed by turning off rectifiers and removing battery line fuse or
connection before attempting work on the wiring connections. Use a voltmeter to verify the
absence of voltage. Clearly mark the correct polarity of the battery leads before commencing work
on DC connections.
Refer to the previous (Installation) chapter for safety precautions and tools required.
CAUTION –When wiring the terminal blocks, take care to bundle and route the wires so they do not interfere with the
circuit breakers. Loose wires may cause the breakers to trip..
5.1 Calculating Output Wire Size Requirements
Wire size is calculated by first determining the appropriate maximum voltage drop requirement. Using the formula
below calculate the CMA wire size requirement. Determine the size and number of conductors required to satisfy
the CMA requirement.
CMA = (A x LF x K) / AVD, where:
CMA = Cross section of wire in circular mil area
A = Ultimate drain in amps
LF = Conductor loop feet
K = 11.1 constant factor for commercial (TW type) copper wire
AVD = Allowable voltage drop
Check again that the ampacity rating of the cable meets the requirement for the installation application. Consult
local electrical codes (NEC, CEC, etc.) for guidelines. If required, increase the size of the cable to meet the code.
5.2 System and Battery Connections
WARNING
Ensure the correct polarity is used for all cable terminations.
Refer to guidelines supplied with the load equipment. Typically distribution cables are sized to provide a 0.5V loop
drop at full load as well as meeting ampacity requirements of the protection fuse or circuit breaker.
Battery cables should be sized for a 0.25V drop from battery to the power system at full load including anticipated
growth. The cables should also meet ampacity requirements. Cables terminating directly on battery posts or
connection details should be secured so that there is no stress on the battery posts. Lead plated lugs and lead
plated or stainless steel hardware should be used on all terminations at vented batteries to reduce corrosion.
Prepare, route and connect cables from power system to battery termination details. Terminating points should be
burnished and a corrosion-inhibiting agent, such as NO-OX-ID “A”, should be applied to all battery terminal
connections.
NOTE: Final connection to battery live should not be made, insulate and leave disconnected or remove the battery fuses.
Switch battery contactors off (if used). See system startup procedure before connecting batteries online.
5.2.1 DC Input to Panel
The DCP03 contains bus bar input for hot and return connections. The bus bar contains 2 sets of 3/8" on 1"
center holes for bus bar or cable connection. The input bars are offset from the rear of the panel to allow for back-
to-back lug connections when cabling. If the DCP03 is configured for 18 load breakers (List 87), these
connections points must be used for connecting external batteries.
The system hot input is located on the left side of the DCP03 (when looking at the rear of panel) and the system
return is located on the right side. Refer toFigure 8.