Vertiv Liebert NXL 500kVA, Руководство по установке

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Vertiv | Liebert
®
NXL
™
500-750kVA UPS Installation Manual | 6
1.4.5 Special Considerations for 1+N Parallel Systems
Consider the grounding configuration of your system before finalizing module placement See
2.6 - Configuring Neutral and Ground Connections .
Vertiv recommends matching the impedance in the bypass path of paralleled systems as closely
as possible.
The impedance mismatch can be minimized by controlling the wiring length of each unit. The
design and the layout of the UPS system and associated panels and cabling should be examined
closely to ensure that cable lengths and impedances are closely matched. The Liebert
®
1+N UPS
module is supplied with a sharing reactor to minimize the impact of cable impedance mismatch.
The cabling impedance must be carefully controlled to ensure good bypass current sharing.
For Liebert
®
NXL ™ Systems, the cabling impedances must be within 10% from maximum to
minimum. If the cabling impedances need to be greater than 10%, contact your Vertiv
representative to calculate whether the system will result in an overload condition when
operating on bypass.
When bringing the 1+N system on-line for the first time or after removing one unit, Vertiv
recommends checking the bypass current mismatch. To check the bypass current mismatch:
1. Place a load on the bypass of each UPS module.
2. View the output current of each unit.
The accuracy of the currents displayed on the UPS module is sufficient for this check. If the mismatch is
greater than 10%, the bypass impedances must be balanced or the load must be limited to less than the
maximum rating.
1.5 System Composition
A UPS system can comprise a number of equipment cabinets, depending on the individual
system design requirements: e.g., UPS cabinet, battery cabinet, maintenance bypass cabinet. In
general, all the cabinets used in a particular installation are of the same height. Refer to the
drawings provided in
4.0 - INSTALLATION DRAWINGS for the positioning of the cabinets as
shown in Figure 1 .
1.6 Cable Entry
Cables can enter the UPS cabinet from bottom or top into the Input/Output (I/O) section of the
unit; see the figures in
4.0 - INSTALLATION DRAWINGS .