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6.3.2.1 Coil Insulation Test
Damage can occur to the search-coils from collisions with debris on the seabed or from other causes.
Usually, damage to the coils appears as a degraded coil insulation resistance rather than a short
circuit. Under these circumstances, the 440 System may continue to work without damage to the SEP
Driver Board, but there will be some loss of accuracy in survey measurements delivered by the
System.
To reduce the possibility of damage to the Driver Board or a loss of survey accuracy due to a partial
insulation breakdown, check each coil before you connect it to the SEP.
Use a sensitive digital meter to measure the DC continuity of each coil between
pins 1 and 2 of the coil connector. This resistance should be 0.30 +/- 0.05.
Use a 500V digital insulation tester to measure the insulation resistance of the coil.
Each coil should show an insulation resistance greater than 200M between the
shell, pin 1 and pin 2 of the coil connector.
Renew any coils that show high resistance, short-circuited windings or an
insulation breakdown.
6.3.2.2 Target Detection Test
Perform this test only if there is a convenient and safe method for lifting and sus-
pending the ROV off the deck.
Power-on the 440 System and allow a period of about five minutes for the System to settle.
If the ROV is resting on the deck of the survey vessel, the proximity of the deck and other metal fittings
will cause the search-coils to saturate. Therefore, use whatever safe means are available to lift the
ROV off the deck and suspend it in the air so that the coils are at least two metres from any metallic
object.
At the SDC, perform a background compensation routine by pressing [Shift +F7] from the
Configuration Menu. Wait ten seconds until the SDC displays a single line of measurements and then
press any key to stop the routine.
Switch off coil drive by pressing [F5] from the Run Display screen and then place a metallic test target
(for example, a spanner) on one of the search-coils. Switch on coil drive by pressing [F5] from the Run
Display screen and check that the display shows a strong signal on the relevant channel. Repeat this
test for all three search-coils, switching off coil drive while you move the test target from one coil to the
next.
6.3.2.3 Oscilloscope Test
Use the SDC oscilloscope display function and check that waveforms are being displayed correctly.
Repeat this test when the ROV is in the water.
6.3.2.4 Altimeter Test
Perform an altimeter test and check that the SEP or the SDC is receiving data packets correctly from
the altimeter.
DPN 402196 Issue 4.1
NOTE
© Teledyne TSS
6 – Operating Procedure
6- 13
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