Cadac R-Type Manuel d'utilisateur télécharger pdf (Page 20)

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The R-Type console is normally supplied with the model 8400 Power Supply Unit.

Each 3U x 19” rack mount power unit supplies all 4 voltages required by the R-Type

console. A single 8400 PSU will power 3 fully loaded R-Type frames.

NOTE:

For console configurations with 4 or more frames, the 8019/8020 systems

must be used, see 3.3.7 Switch-Mode Power Supply Units (8019 & 8020).

Cadac consoles are designed to allow the use of two independent power supply sys-

tems in a redundant configuration – “main” and “backup”. Both power supply units

are used to power the console system, so that under normal conditions, the ‘load’ is

shared equally between the “main” and “backup” PSU. If a fault occurs in one of the

power units (causing it to ‘shut-down’), the remaining power unit will power the con-

sole (see fig. 3-11).

Designate one power supply unit as “PSU 1" and the other as “PSU 2". PSU 1 and

PSU 2 should be connected to the same

phase

and on the same ‘spur’, wherever

possible. In situations where it is necessary to provide a separate ‘feed’ to each PSU

system, make sure that the cable lengths are the same. This is to minimize any

induced a.c. power input noise by ensuring that the “EARTH IMPEDANCE” is the

same for both PSU-systems.

The a.c.-input connectors on each power supply unit have three conductors: ‘LIVE’

(brown), ‘NEUTRAL’ (blue) and ‘EARTH’ (yellow/green). For safety and electromag-

netic compatibility considerations, it is essential that the ‘EARTH’ conductor is con-

nected on all PSUs

and

the a.c. supply has an ‘EARTH’ conductor that has a

continuous circuit to the “zero-signal reference potential” point in the building. The

ZSRP point in a building is usually found near the place where the a.c. ‘mains’ supply

enters the building (often referred to as the “MAIN GROUND REFERENCE EARTH

ELECTRODE SYSTEM”). The basic concept for correct a.c. mains wiring distribution

is shown in figure 1-1. If you need further information about this complex subject,

please refer to “Grounding Systems and their Implementation” by Charles Atkinson

and Philip Giddins published in the AES Journal Vol. 43, No. 6 – June 1995.

The grounding scheme in CADAC consoles is designed to meet the rigorous EEC

Electromagnetic Compatibility

requirements (EMC Directive - 1996). Any RF noise

induced in the console frame(s) is directed to the “local” ZSRP, which is the metal-

work of the power supply units. In order to take full advantage of the “RF noise immu-

nity” capability of the CADAC system, PSU a.c. mains cables and the a.c. mains

supply EARTH conductor must be connected correctly.

GND BAR GND BAR

AREA

GND BAR

PSU1

PSU2

BUILDING

FIG 3-11. AC mains grounding diagram (single phase 208-240V)

1 2 ... 15 16 17 18 19 20 21 22 23 24 25 ... 138 139

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Cadac R-Type Manuel d'utilisateur Page 20

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