Instruction manual

NGA 2000 MLT Hardware
INSTALLATION
5 - 32
Emerson Process Management GmbH & Co. OHG
Instruction Manual
90002929
07/2006
5.5 Wiring Signal Terminals
Emerson Process Managament has taken any effort during the MLT series development process
to ensure electromagnetically compatibility (EMC; concerning emission and immunity), stated by
EMC measurements according EN 61326.
Nevertheless EMC is not only influenced by the instrument‘s design, but widely by the installation
procedure at site, too. Take care of the following sections and measures described within to ensure
safe and trouble-free analyzer operation!
5.5.1 Electrical Connections in General
To minimize electromagnetically interferences by the analyzer‘s environment it is necessary to
carefully execute all electrical connections between the analyzer and other instruments:
❏ It is recommended to use shielded cables for signal lines, only!
Shield has to be connected to the housing at both ends of one connection (fig. 5-22).
Fig. 5-22:Shielded Signal Cable,
shield connected at both ends
Local on-site conditions usually differ from test conditions and may require special measures. This
is when strong fields are expected, potentially generating high parasitic currents on the cable shield
. Such currents result in differences of potential between connected housings.
Two possible measures to avoid parasitic currents are described, whereat installation personnel
familiar with EMC problems has to decide about the use of either measure:
❏ Shield is connected at one side of the cable only (recommended to the analyzer‘s housing):
Protection against external distrubances is increased but influence by parasitic currents is
prevented due to opening the ground loop.
Fig. 5-23: Shielded Signal Cable,
shield connected at one end
WIRING SIGNAL TERMINALS: ELECTRICAL CONNECTIONS IN GENERAL