External Protective Devices | Liebert NX UPS System guide

Single Module UPS Installation

1.4.4Clearances

The Liebert NX has no ventilation grilles at either side of the UPS. To enable routine tightening of power terminations within the UPS, in addition to meeting any local regulations, Liebert recom- mends providing adequate clearance in the front of the equipment for unimpeded passage of person- nel with the doors fully opened. It is important to leave of 150mm (5.9") clearance behind the UPS to permit adequate circulation of air coming out of the unit.

1.4.5Access

The component layout of the UPS supports front and top access while servicing, diagnosing and repairing the UPS, thus reducing the space requirement for side and rear access.

1.4.6Final Positioning

The UPS cabinets are fitted with casters on the base to allow ease of movement and positioning.

! WARNING

Casters are strong enough for movement across even surfaces only. Caster failure could occur if they are subjected to shock loading.

When the equipment has been finally positioned, ensure the adjustable feet are set so that the UPS will remain stationary and stable.

1.4.7Floor Anchoring

Diagrams in 4.0 - Installation Drawings show the location of the holes in the base plate through which the equipment may be bolted to the floor. If the equipment is to be installed on a raised floor it should be mounted on a pedestal suitably designed to accept the equipment point loading. Refer to the base view Figure 21 to design this pedestal.

1.4.8Cable Entry

Cables can enter the Liebert NX UPS and battery cabinet from below. Cable entry is made possible by removing a blanking piece fitted at the bottom of equipment to reveal the cable entry hole.

1.5External Protective Devices

Circuit breakers or other protective devices must be installed in the AC supply, external to the UPS. This chapter provides guidelines for qualified installers who must have knowledge of local wiring practices pertaining to the equipment to be installed.

1.5.1Rectifier and Bypass Input

Overcurrent protection must be installed at the distribution panel of the incoming main supply. The protection must discriminate with the power cables current capacity and with the overload capacity of the system (see Table 35). As a guideline, a thermomagnetic circuit breaker, with an IEC 60947-2 trip curve C (normal) for 125% of the current listed in Table 1 is suitable.

Split-Bypass—If a split-bypass is used, install separate protective devices for the rectifier and for the bypass in the incoming mains distribution panel.

NOTE

Rectifier and bypass input sources must be referenced to the same neutral potential.

NOTE

For IT power systems, four-pole protective devices must be used, external to the UPS, both upstream of the input distribution panel and downstream (toward the load).