Chapter 3 Electrical Installation 17
Liebert APM 90 Integrated Modular UPS User Manual
1. Max. input current at full load.
2. Non-linear loads (such as switch mode power supplies) affect the design of the output and bypass neutral cables. The
current
circulating in the neutral cable may exceed the nominal phase current. It can be up to 1.5 times the nominal phase current.
3. Battery (36-block as an example) discharge current at EOD. The max. battery neutral line current can reach half of the
battery positive/negative current.
3.1.3 Minimum Distance From Floor To UPS Connection Point
Table 3-2 provides the minimum distances from the floor to the UPS connection points.
Table 3-2 Distance from floor to UPS connection point
UPS connection point Minimum distance (mm)
AC input 1087
AC output 1156
Battery power 1087
Earth bar 1087
3.1.4 Notes
The following are guidelines only and superseded by local regulations and codes of practice where applicable:
1. The neutral line shall be sized according to the load characteristics. It should be sized for the max.
output/bypass phase current to 1.5 times the output/bypass phase current.
2. The PE cable shall be sized in accordance with the AC supply fault rating, cable length and type of protection.
Typical CSA is 75mm
2
according to AS/IEC60950-1. Follow the most direct route possible to connect the PE
cable to the cabinet.
3. Consideration should be given to the use of paralleled smaller cables for heavy currents, as this can ease
installation considerably.
4. When sizing battery cables, a maximum volt drop of 4Vdc is permissible at the current ratings given in
Table 3-1.
5. To minimize the formation of electromagnetic interference, do not form coils.
3.1.5 Power Cable Connecting Terminal
The input terminals, battery terminals and PE terminals are shown in Figure 3-2. The output terminals are
shown in Figure 3-3 ~ Figure 3-5.
3.1.6 Protective Earth
The PE cables should be connected solidly to the PE terminals (see Figure 3-2).
The cabinet and cable troughs shall be earthed according to the local regulations. The earth cables shall be
tied up reliably to prevent the loosening of the earth cable tightening screws when the earth cables are pulled.
Warning
Failure to follow adequate earthing procedures may result in EMI or hazards involving electric shock and fire.
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