APC MX28B-1200, MX28B-2400 manual Ventilation, Terminal Block

Revision B MX28B-1200 PRODUCT MANUAL

5.1.7 Ventilation

The rectifiers have fans that provide front to rear airflow for internal cooling. The MX28B housing should mounted such that there is free airflow to the front and top of the unit. [Refer to Section 4.8 for environmental characteristics.]

5.2 AC Service and Ground Connections

***** WARNING *****

Ensure that all of the dc and external ac circuit breakers are in the OFF position prior to connecting service to the power plant. Confirm that all voltages have been removed including any battery sources before proceeding.

The MX28B dc power plant requires the supply of 208/220/240V ac, single- phase, 50/60 Hz power through individual external 20-amp two-pole circuit breakers to the ac input terminal block connections for each rectifier in the system. The ac wiring, from the ac input terminal block connections to the hot-pluggable ac input connector for each rectifier, is factory installed.

The ac input enclosure, located at the top rear of the MX28B housing, is provided with nine ¼ -inch conduit pilot holes in the top plate (Figure 5-2). Remove the ac input enclosure from the box frame in order to punch or drill the appropriate number of conduit openings for the conduit size(s) desired. Do not leave the ac input enclosure in place when punching or drilling holes in order to prevent metal pieces from falling into the power system.

AC Input

Enclosure

Access

Opening

Vertical channel for AC wiring

Figure 5-2 AC Wiring Access

AC wiring passing through the conduit will be routed through the access opening in the ac input enclosure into the vertical wiring channel where safety ground bar and rectifier input terminal blocks are located. The terminal block(s) is labeled as Rectifier 1 through Rectifier 4 with each position having inputs designated “L1” and “L2” for connection of the two ac wires (Figure 5-3). Each terminal block represents connections for one shelf, with positions 1 through 4 corresponding to the rectifier shelf positions numbered from left to right as view from the front.

The suggested wire size is #10 AWG rated at 90°C or higher; however, the ambient temperature and number of wires in a

MX28B-1200/2400

Figure 5-3 AC

Terminal Block

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