Cadac S-Type - Manual (Page 12)

2-2 Connections and setup
S-Type Revision S2005-6
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The S-Type console is supplied with the model 8500 Power Supply Unit. Each 2U x
19” rack mount power unit supplies all 4 voltage required by the S-type console. If
more than one frame is to be used, then the 8400 Power Supply Unit may be used.
Cadac consoles are designed to allow the use of two independent power supply sys-
tems in a redundant configuration - main and back-up. 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 back-up 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.
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 on the same ‘spur’, wherever possi-
ble. In situations where it is necessary to provide a separate “feed” to each PSU sys-
tem, make sure the cable lengths are the same. This is to minimize any induced AC
power input noise by ensuring that the ‘EARTH IMPEDANCE’ is the same for both
PSU-systems.
The AC input connectors on each power supply have three conductors: LIVE
(brown), NEUTRAL (blue) and EARTH (green/yellow). For safety and electromag-
netic compatibility considerations, it is essential that the EARTH conductor is con-
nected on all PSUs and the AC 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 AC mains supply enters the
building (often referred to as the MAIN GROUND REFERENCE EARTH ELEC-
TRODE SYSTEM). The basic concept for correct AC mains wiring distribution is
shown in figure 2-2. 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 metalwork
of the power supply units. In order to take full advantage ‘RF noise immunity’ capabil-
ity of the CADAC system, PSU AC mains cables and the AC mains supply EARTH
conductor must be connected correctly.
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FIG 2-2. AC mains grounding diagram (single phase 200-240V)