VTI by M. Davis DC Fused Distribution Panels (FDP-DC)
DC Fused Distribution Panels are available for 24VDC, 48VDC, and 125VDC applications. 250 VDC and 500VDC are also available on special order. The FDP-DCs are available in Main Lug Only (MLO), Main Breaker (MB), and Main Fuses in series with the Main Breaker (FD) configurations.
FDP-DCs for 24VDC and 48VDC are packaged in the same enclosures and interiors as the standard FDP for single phase AC applications.
The FDP-DC utilizes single pole fuse holders in series with single pole circuit breakers, as the fuse holders are not rated as load break devices.
Historically, 125VDC Distribution systems have always been floating systems consisting of a battery, charger, and distribution panel containing two pole breakers: one for the Positive (+) and the second for the Negative (–) polarity. The main reason for this system configuration is system reliability. In a floating distribution system, if one polarity becomes grounded, the total system will remain operational. The chances of both the Positive and Negative polarities becoming grounded at the same time is extremely low. In addition, most DC systems contain a simple “GROUND DETECTOR” consisting of two nominally rated DC pilot lights connected in series between the Positive and Negative polarities with the center of the pilot lights connected to “Ground.” Normally, both lamps will glow at a low intensity since they are connected in series between the full system voltage. Therefore, if a “Ground” occurs on one polarity, one lamp will light at full intensity while the other lamp will not be lit. The source of the “Ground” may be determined and corrected before any system damage can occur.
The 125 VDC Fused Distribution Panels have all 2 pole branch circuits with a 2 pole DC rated branch circuit breaker (used as a switch to open the circuit under load) and with two 150 VDC fuses, one each in the Positive and Negative legs of the DC circuit.
The 125VDC FDPs are available with main bus ratings of 125 amps, 250 amps and 400 amps. Since all of the 125 VDC circuits are 2 pole circuits in the standard configurations, the number of branch circuits are 8 (an 18-single pole circuit panel), 14 (a 30-single pole circuit panel), and 20 (a 42-single pole circuit panel).
On special order 125VDC FDPs can be provided with a higher number of branch circuits. For example; the maximum number of branch circuits for the 400 amp Main Breaker panel is 32 – 2 pole circuits and for the 250 amp Main Breaker panel is 44 – 2 pole circuits
Fuses for the 125VDC FDP:
Ferraz Shawmut Type A15QS(X) (where ‘X’ = Current Rating)
- Fuse Current Ratings from 1 to 30 amps @ 150 Volts DC with a 100 KAIC rating @ 150 VDC
- Physical Size: 13/32” dia X 1.5” long NEC Midget size
- Tested to UL STD 198L and UL recognized
- 2 pole Ultra-Safe touch free
- Rated @ 30 amps @ 125VDC NON-LOAD Break
- The modular fuse holder can be supplied with blown fuse indicators as an option