Vertiv Liebert NXL 500kVA, Руководство по установке

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Vertiv | Liebert
®
NXL
™
500-750kVA UPS Installation Manual | 9
The following are guidelines only and are superseded by local regulations and codes of practice
where applicable:
• Take special care when determining the size of the neutral cable (grounded conductor), because current
circulating on the neutral cable may be greater than nominal current in the case of non-linear loads. Refer
to the values in
Table 13 .
• The grounding conductor should be sized according to the fault rating, cable lengths, type of protection,
etc. The grounding cable connecting the UPS to the main ground system must follow the most direct
route possible.
• Consideration should be given to the use of paralleled smaller cables for heavy currents, as this can ease
installation considerably.
• AC and DC cables must be run in conduits according to local codes, national codes and standard best
practices. This will prevent creation of excess EMI fields.
2.3 Sizing the Input Breaker feeding a Liebert
®
NXL
™
UPS
The rectifier nominal input current value ( Table 14 ) is based on providing enough power to
operate the inverter at full rated load when the input voltage is nominal. The published rectifier
maximum input current value is based on the maximum input current limit setting of 125%.
The recommended input breaker ampacity is based on the NEC calculation for a branch circuit
with the current limit set at the maximum value. The calculation for a 100% rated breaker is 100%
of the nominal current (continuous) plus 100% of the difference between the nominal and the
maximum currents (noncontinuous).
The rectifier input current limit can be adjusted from 25% to 125% of the nominal value. This
setting is only accessible to a factory-trained service engineer. The effect of changing this setting
is similar to that of changing the setting of the trip unit on a solid state circuit breaker. With a
lower current limit setting the calculation for the branch circuit will result in a lower value.
The input current limit should not be set less than 105% of the current needed to support the
inverter at full load for normal operation. This results in sufficient power to recharge the battery in
a reasonable time and to operate over the published input voltage range.
2.3.1 Power Cable Connection Procedure
The rectifier input, bypass, output and battery power cables (all require lug-type terminations)
are connected to busbars in the I/O sections (refer to
4.0 - INSTALLATION DRAWINGS ).
Equipment Ground
The equipment ground busbar is in the I/O sections as shown in (refer to 4.0 - INSTALLATION
DRAWINGS ). The grounding conductor must be connected to the ground busbar and bonded to
each cabinet in the system.
All cabinets and cabling should be grounded in accordance with local regulations.
NOTE
Proper grounding reduces problems in systems caused by electromagnetic interference.