Unit installation

Troubleshooting and Maintenance
974-24007001/4.1 69
5.3.4 Winch Slip-Rings and Trawl Cable
The winch slip-rings and trawl cable are the umbilical cord between
the processor unit and trawl unit electronics, and are critical to the
proper operation of the Simrad FS Trawl Monitoring system.
Damaged, worn or poorly maintained cable or slip-rings will
degrade the performance of the system and may cause or lead to a
complete system failure.
Worn, dirty or wet winch slip-rings may add noise, current spikes or
additional losses to cable. Slip-ring assemblies should be checked
regularly for wear and proper sealing against the weather. Slip-ring
technology has improved considerably over the past several years
and sealed units from several suppliers (such as IEC Corp.) have
proven to be very reliable.
Trawl cables, particularly the plastic jacketed type, are extremely
susceptible to damage and wear that may adversely affect system
operation. Proper maintenance is very important to ensure cable
losses are minimized and adequate isolation between the cable
conductors and sea water are maintained. Common problems
include poor splices, water damage, cracked or worn outer casing
(insulating jacket), or severed cable. The trawl cable should be
routinely checked for damage and affected sections removed,
splices redone or the entire cable replaced as required.
The pigtails spliced to the end of the trawl cable are susceptible to
damage and corrosion and must be checked and if necessary
replaced every time prior to connecting the trawl unit. When not in
use the pigtail should be wrapped in a plastic bag and stored out of
the weather and away from being stepped on or damaged in any
other way.
Polarity of the signals applied to the trawl cable (coax) may also be
important in the proper operation of the system. To provide
optimum shielding from noise, we recommend the positive signal
be applied to the center conductor and the negative signal to the
shield.