Nortel Meridian Meridian 1, Планирование, установка и инструкции по эксплуатации

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Page 22 of 536 Chapter 3 — System and site requirements
553-3121-210 Standard 3.0 January 1999
Grounding requirements
Before installing the Option 11C Compact system and applying AC power,
measure the impedance of the building ground reference. (An ECOS 1023
POW-R-MATE or similar meter is suitable for this purpose.) If the ground
path connected to the Option 11C Compact has an impedance of 5 ¾ or more,
better grounding arrangements should be made. Any improvements to the
grounding system should be made before the system is installed.
Other grounding requirements are as follows:
• The impedance of the link between the ground post of the system
cabinets and the Single Point Ground (SPG) to which it is connected
must be less than 0.25¾. Reliable system operation depends on
high-precision internal circuitry, which can be damaged by transients in
its supply conductors and ground system. Damage to sensitive devices
due to transients may not be immediately apparent: degradation may
occur over longer periods of time.
• Do not connect the single point ground conductor from the Option 11C
Compact system to structural steel members or electrical conduit. In
particular, do not tie this conductor to a ground source or grounded
electrode that is not hard-wired to the building reference conductor.
• Ground conductors for the Option 11C Compact system:
— must be a minimum of #6 AWG at any point
— must be routed through the same conduit as the phase conductors
serving the system
— must not be smaller than any phase conductor in the same conduit
— must not carry current under normal operating circumstances
• All ground conductors in the building:
— must be isolated from the neutral bus except at the service entrance
to the building
— must be hardwired to the main ground reference
• Avoid spliced conductors. Continuous conductors have lower impedance
and are more reliable than spliced ones.