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MAN0889_Issue 3_03/13
3. Installation and Operation
3.2.5 Orientation
The Searchline Excel Cross-Duct units should be mounted on vertical, flat surfaces such that the optical axis
is horizontal. Ensure the surface is rigid and stable. Fit additional supports prior to installation if necessary
(see note on Vibration, above).
The Heated Reflector Panel should be mounted directly opposite, and perpendicular to the optical axis of the
Transmitter and Receiver unit. If the duct walls are not exactly vertical or parallel, the position of the cut out
for the retro panel must be adjusted to compensate.
It is not advisable to install the Cross-Duct Excel on the top or bottom of the duct. In this orientation the
Reflector Panel or the Transmitter and Receiver unit will be vulnerable to the build up of contamination.
3.2.6 Access for Cleaning
Searchline Excel Cross-Duct Transmitter and Receiver unit and Heated Reflector Panel will need to be cleaned
regularly. In the case of the Reflector Panel it may need to be removed from the duct to clean the window. It
is advisable to provide an access point in the duct, adjacent to the reflector panel, to allow it to be cleaned.
3.3 Electrical Connections
3.3.1 General
Searchline Excel Cross-Duct complies with the EN50270. In order to maintain compliance with these standards
it is essential that the electrical installation of Excel is engineered correctly.
Electrical installation standards vary for different countries, companies and applications and it is the responsibility
of the installation design authority to determine the applicable standards and ensure compliance with them.
When designing electrical installations for Excel, Honeywell Analytics recommend that the installation design
authority considers the following:
a.
The unit cases should not, if possible, be connected to electrically noisy (dirty) metalwork or conductors.
Preferably, the case (internally connected to the green/yellow GND wire) should be connected to a low
noise instrument (clean) earth. See also para e. below. In order to facilitate electrical isolation of the
Searchline Excel from a noisy earth an isolation kit is supplied. This kit should be fitted as standard unless
local regulations forbid this.
b. The entire length of the field cabling connected to each unit should be fully shielded. This should be connected
to a low noise (clean) earth.
c.
The low noise instrument (clean) earth system should only be connected to safety earth (usually dirty)
at a single point on the entire site/installation. This connection should be made in such a manner that it
does not introduce noise onto the low noise instrument earth. Star earthing arrangements minimise earth
current crosstalk.
d. The shields of the field cabling should not be connected such that earth loops are produced, or in a manner
that will result in the shields carrying large currents from heavy plant or equipment.
e. Ideally, the field cable shield should be connected to the unit s green/yellow GND wire, providing a single,
continuous earth shield. This connection must not be allowed to complete an earth loop.
f.
The earth bonding arrangement must ensure that the maximum peak voltage between the unit case earth
and any field cable conductor is less than 350V. Voltages in excess of this can cause permanent damage
to the unit s RFI protection filters.
g.
The use of a single, screened cable for each gas detector ensures maximum screening and minimum
crosstalk. Cabling arrangements which use a single cable for connecting a number of field devices
compromise screening, increase the potential for crosstalk and prevent implementation of true star earthing.
Searchline Excel Cross-Duct Technical Handbook
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