American Power Conversion MX28B200 user manual Load Connections, GMT Fuse Installation

GMT Fuse Installation

Fuse holders that accommodate GMT fuses are located on the interface card mounted in the top left side of the unit. Insert the fuse in the holder; observing the tripped indicator is correctly oriented. These fuse holders are only connected to -48VDC if the system has been purchased with the GMT fuse option. This option supplies -48VDC to lugs on the interface card through a 50 Amp circuit breaker located in circuit breaker Position 1. The interface card provides fuse holders for eight fuses, labeled “F1” through “F8”, which can be used for small -48V DC loads. Use the chart shown in Figure 3.7-2to help determine what size fuses will carry the desired current. Refer to Figure 3.8-3for Interface board GMT fuse locations.

		AMBIENT TEMPERATURE
		20° C	50° C	60° C
	10 Amp	7 Amp	6 Amp	5 Amp
FUSE SIZE
	12 Amp	8 Amp	7 Amp	6 Amp
	15 Amp	10 Amp	9 Amp	8 Amp
	Figure 3.7-2 GMT Fuse Temperature De-rating Chart

3.8. Load Connections

Cable Size Considerations

The DC load cable(s) should be sized sufficiently large to limit the voltage drop from the MX28B DC power plant to the loads per system design requirements. The cable(s) must also carry the full load current during battery operation. During battery operation the voltage will be lower and for constant power loads, therefore the current will typically be higher. If assistance is required to determine the necessary cables for the application, contact your sales representative or APC.

Circuit Breaker Connections (1 to 50 Amps)

Connections for 1 to 50 amp DC loads require standard two-hole lugs with holes for #10 screws (810-0032) on 5/8” centers and are located directly above the corresponding circuit breaker. The load returns connect to the return bus located just above and rearward of the breaker connection points as seen in Figure 3.8-1 The return bus provides 24 sets of threaded #10-32 holes on 5/8” centers and four sets of threaded ¼-20 holes on ¾” centers for connection of two-hole lugs on load return wires.

MX28B200/400 –48 VDC User’s Manual (990-9133) Page 15