abem WalkTEM 2, Краткое руководство пользователя

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ABEM WALKTEM 2 ABRIGDED USER MANUAL
3. DAMPING RESISTOR DECISIONS
When we rapidly shut off the current in a transmitter loop, a ‘ringing’ effect is created – an unwanted
oscillating and decaying current. We use a damping resistor in parallel with the transmitter loop to minimise
this effect and the size of the resistor will depend upon the loop properties and the ground over which it lies.
In the original WalkTEM all damping resistors were mounted externally and the choice was entirely down to
the operator and their experience of how a ‘good’ sounding s hould look. With the WalkTEM 2, there are a
range of damping resistors installed inside the TX unit, which it is possible to test and analyze in order to
determine the best possible resistance value for any given loop or survey area. The analyzer will also run a
test on the loop without any of the internal resistors connected thus it would still be possible to mount a
custom resistor externally and review its suitability; mounting of an external resistor is covered in Part D of
this section. The analysis process would be as follows:
A. Set-up the instrument with a transmitter loop:
-
connect the RX and TX units plus, as a minimum, the
transmitter loop and power on;
-
you need an active project and to select a measurement
script before the
“Analyze” button will activate.
B. Select “Analyze”, press ENT, and follow the screen prompt:
-
take out the Rogowski coil (below right) and open it, if necessary, by pulling the free end of the loop ( A )
from the blue connector;
-
wrap the loop around one of the transmitter coil leads, using the arrow on the blue connector to orient
in the correct direction with respect to the direction of current flow in the transmitter loop;
-
plug the other end of the Rogowski coil into Input B on the left side of the RX unit (you may need to
unplug the RC-200 from Input B);
-
press “OK”.
Sync
cable
Power
RX
TX
TX Loop
TX
A