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Note: See Appendix 5 for information regarding the AC junction box.
Fig.1.1 AC – DC Earth Link
6.3.
Upstream Over-current Protection
There are two considerations to consider when selecting an appropriate fuse/circuit breaker.
- The upstream protection should protect the downstream cable from overload situations.
- Discrimination should be maintained with the downstream device fuses.
Cable Rating
The maximum current drawn by the DC power system is 12.5A per 2kW rectifier (6.2A for 24V system and
48 VDC/1 kW rectifier modules), or 37.3A (18.7A for 24V system and 48 VDC/1 kW rectifier modules) per
fully populated rectifier shelf at a minimum input voltage of 175V AC and full output power. The upstream
protection device must be able to supply this load under all conditions without tripping. Therefore, typically
at least 20% headroom is allowed for the protection device, making its minimum rating 15A/per 2kW
rectifier (7.5A) or 44.8A (22.5A) for fully populated rectifier shelf.
Note: The current carrying capacity of cables is dependent on the type of cable used. Please check with your
local supplier and local regulations for appropriate sizing.
6.4.
Discrimination
Discrimination ensures that the upstream circuit breaker or fuse does not blow if a rectifier input fails (short
circuit). Therefore, it is important to ensure the upstream protection discriminates with the internal fuse
of the rectifier. The fuse used in the RM2048/24, C2R-2000, and C2RX- 2048 rectifiers is a slow-blow 15A
fuse. The tripping curve for this is shown in Appendix 4 at the rear of this manual.
Earth
Stud
Newmar • 1580 Sunflower Ave, Suite 100, Costa Mesa, CA 92626
Phone: 714-751-0488 • E-mail: techservice@Newmarpower.com
AC-DC Earth Link
( Remove link for
Isolated DC Output)
8
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