Guideline Geo ABEM Terrameter LS 2 - User Manual

ABEM Terrameter LS 2
ELECTRICAL RESISTIVITY
Quick guide for 4-cable 48 & 64 electrode systems
For more detailed and in-depth instructions regarding proper usage of the instrument, please consult the ABEM Terrameter LS 2 User Manual .
The current and voltage transmitted can be life threatening. The emergency button must
be engaged while working with connected cables and electrodes. Before starting ANY
measurements, ensure survey cables and electrodes are not being handled or touched.
Keep connectors dry and clean. Poor connector handling and maintenance are the
main causes of cable failure. Always interconnect dust caps to keep them clean and
dry during measurements (right).
LAYOUT PROCEDURE
A. Setting-up for survey
- Measure a straight line along the ground. Profile length
= (no. of electrodes – 1) * electrode spacing.
- Hammer electrodes vertically into the ground along
survey line (depth < 1/10 of the electrode spacing).
- Place Take-out 1 of Cable 1 adjacent to the first
electrode in the spread. Walk cable reel 1 along the
survey line until all take-outs on the cable are aligned
with an electrode.
- Next, place Take-out 1 of Cable 2 at the next available
electrode. Walk cable reel 2 along survey line until all
cable take-outs are aligned with an electrode.
- Repeat with Cables 3 & 4. The last take-out (highest
number) on Cable 4 should coincide with last electrode.
- NOTE: If the electrode spacing
is much smaller than the cable
take-out spacing, avoid
coiling and excessive
overlapping of spare cable
between the take-outs (right).
- Take-out numbers should always increase along profile.
- TIP: To avoid confusion when processing results, profiles
should run in southerly-to-northerly or westerly-to-easterly
direction.
- Finally, place the ABEM Terrameter LS 2 instrument and
external battery in the middle of the survey line (between
Cable 2 and Cable 3).
B. Connecting and powering the system
- Press the emergency stop button in; this should be
the case whenever handling the cables / electrodes.
- Use cable joints to connect Cable 1 & 2 and Cable 3
& 4. Important: cable joints are directional. Ridges
on the cable joints should be towards the instrument.
- Connect jumper wires between cable take-outs and
electrodes (preferably connected to upright section).
- Put Cable 2 into Connector 1, and Cable 3 into Connector 2
on the instrument end panel.
- Using the external power cable, connect the instrument to
an external 12V car battery.
- Press the power button on the instrument to start.
Clicking noises will be audible during this start-up as
the instrument exercises the relay matrix.

Summary

Layout Procedure

Setting-up for survey

Steps for setting up the survey line, placing electrodes, and laying out cables for resistivity measurements.

Connecting and powering the system

Instructions on connecting cables, power, and safely initiating the instrument for operation.

User Interface and Keyboard Functions

Welcome View & Screen Features

Overview of the instrument's screen layout, navigation menu, tabs, view, and status bar elements.

Keypad Functions

Explanation of how to use the instrument's keypad and its mapping to functions for navigation and operation.

Project and Settings

Create Project & Task

Guide to creating new projects and tasks, including setting up survey parameters like spread and electrode spacing.

Receiver & Transmitter Settings

Receiver Settings

Configuration options for the receiver, including measure mode, stacking, error limits, and acquisition times.

Transmitter Settings

Configuration options for the transmitter, covering current/voltage limits, electrode testing, and load variation.

Measurements

Measurement Configuration

Steps to configure measurement settings, including cable setup and initiating the measurement process safely.

Electrode Contact Test

Procedure for testing electrode contact resistance before starting measurements and troubleshooting failures.

Measurement Progress

How to monitor real-time measurement progress, view results, and interpret status bar information.

File Management

USB Project Download

Instructions for downloading project data from the instrument to a USB storage device.

USB Task Download

Instructions for downloading specific tasks from the instrument to a USB storage device.

Overview

1. Function Description
2. Usage Features
3. Maintenance Features

The ABEM Terrameter LS 2 is an electrical resistivity instrument designed for geophysical surveys, primarily for 4-cable 48 and 64 electrode systems. Its core function is to measure electrical resistivity and induced polarization (IP) of the ground, providing insights into subsurface geological structures.

Function Description:

The instrument operates by transmitting current into the ground through electrodes and measuring the resulting voltage differences, which are then used to calculate resistivity and IP. It supports various measurement modes, including pure resistivity (Res), resistivity and traditional 50% duty cycle IP (Res, IP), and novel 100% duty cycle IP (IP 100%). The system is designed to handle multiple electrodes, allowing for efficient data acquisition over survey lines. It features a relay matrix that exercises during startup, indicating its readiness for operation. The device can record full waveform data, capturing the complete output and input current and voltage patterns during the measurement cycle, which can be valuable for detailed analysis, though it results in larger project files. It also includes an electrode contact test function to ensure proper electrode grounding and connection before measurements begin, which is crucial for data quality. The instrument provides real-time monitoring of measurement progress, displaying parameters such as channel number, electrode pairings, measured quantities (voltage or current), standard deviation, resistance, apparent resistivity, and chargeability.

Usage Features:

The ABEM Terrameter LS 2 is designed for field use, with a layout procedure that involves setting up a straight survey line, hammering electrodes vertically into the ground, and aligning cable take-outs with electrodes. It supports both 48 and 64 electrode systems, requiring the use of up to four survey cables. The instrument is typically placed in the middle of the survey line, between Cable 2 and Cable 3, along with an external 12V car battery for power. Cable joints are directional, with ridges indicating the direction towards the instrument, ensuring correct connection. Jumper wires are used to connect cable take-outs to electrodes.

The user interface includes a navigation menu with options for Projects, Settings, Measure, and Instrument, each with corresponding tabs. The 'Welcome View' displays recent activities and instrument information. Users can create new projects and tasks, defining the spread (e.g., 4x12 for 48 electrodes or 4x16 for 64 electrodes) and protocol (electrode array). Minimum electrode spacing can be set via a virtual keyboard.

Receiver settings allow users to select the desired measurement mode, define stacking and error limits to improve data quality, and set delay and acquisition times to optimize noise reduction and IP effect avoidance. IP windows rely on pre-loaded settings. The power line frequency can be selected based on the survey region (50Hz or 60Hz), and the sample rate for full waveform recording can be defined.

Transmitter settings include minimum and maximum current, power, and voltage limits, which provide warnings if actual values fall below thresholds. The 'Electrode Test' feature, typically set to 'Focus One', tests contact resistance and connection of each electrode. Users can define 'Bad' and 'Fail' electrode thresholds. Load variation margin can be set to maintain constant current during measurements.

During measurements, the 'Progress' view monitors real-time data. The instrument provides warnings for high standard deviations, excessive negative IP values, or error messages. The measurement progress is indicated by the number of completed measurements relative to the total. The emergency stop button is a critical safety feature that must be engaged when handling cables and electrodes and disengaged to start measurements. If an electrode test fails, the instrument provides feedback on which electrodes are 'Bad', 'Fail', or 'No Contact', prompting the user to troubleshoot by checking jumper wires, electrode grounding, or repositioning. Individual electrodes or entire cables can be excluded or forced into use if necessary.

Maintenance Features:

The manual emphasizes the importance of keeping connectors dry and clean, as poor handling and maintenance are the primary causes of cable failure. Dust caps should always be interconnected during measurements to maintain cleanliness and dryness. The instrument's robust design is intended for field conditions, but proper care of cables and connectors is highlighted as essential for longevity and reliable operation.

For data management, the ABEM Terrameter LS 2 supports downloading data via a USB storage device or through PC companion software, ABEM Terrameter LS Toolbox, using an Ethernet or Wi-Fi connection. Projects and tasks can be exported from the instrument to a USB device, with the project database file being crucial for opening data in the Toolbox for quality assurance and filtering. The system also includes notification icons for battery status (external and internal), GPS status, and time of day, which can aid in monitoring the instrument's operational health. The emergency stop button serves as a critical safety and maintenance feature, preventing current and voltage transmission during handling of potentially life-threatening components.

Guideline Geo ABEM Terrameter LS 2 Specifications