PCMx Transmitter Signal ConnectionFollow
WARNING! Appropriate safety procedures must be followed before removing pipeline CP connection from the rectifier. Before handling connection leads switch both the rectifier and PCMx transmitter OFF.
Connection to a rectifier
A rectifier station is an ideal place to connect the output of a PCMx transmitter as it provides connections to both pipe and an anode bed for a suitable ground. The rectifier can also be used to power transmitter using the mains supply. The Tx-150PCM can also be powered from the rectifier output.
|1. Disconnect both pipe and anode cables from the rectifier.
2. Ensure the transmitter is turned off.
3. Connect the White signal output lead to the pipe cable.
4. Connect the Green signal output lead to the anode cable.
When connection to a rectifier is not possible
Connection of a PCMx transmitter can be made to a suitable test point or directly to the pipeline itself. Connect the White output cable to the connection that is connected directly to the pipeline and connect the Green output lead to either a sacrificial anode or use a suitable earth stake.
If using a sacrificial anode, make sure that it is not directly connected to the pipeline. When using an earth stake, position the stake 45m / 150 feet away from the pipe. To achieve a suitable earth, it may be necessary to use more than one earth stake linked together.
When connecting to an electrical isolation joint, you may connect the White lead to one side of the joint and the Green output lead to the opposite side of the pipe section as this can often provide a suitable ground connection.
Conducting a pipeline survey
Locate and pinpoint the pipe
With the magnetometer foot attached, switch on the PCMx receiver.
- Use the key to match the frequency mode of the receiver to the operating frequency of the transmitter. If you intend to conduct a survey of the pipeline, ensure both transmitter and receiver are set to one of the mapping frequencies, (ELF, ELCD or LFCD).
- If you wish to capture location ensure the internal GPS is switched on (see details below).
- Set the antenna mode to Peak+ by pressing the antenna key. The screen will display Once in Peak+, holding down the antenna key alternates between adding Guidance or Null modes to the Peak reading. Add Guidance mode, by holding the antenna key down; Guide appears in the lower left corner of the display. Two holds may be required depending on the starting mode.
- Use map information or pipeline markers to determine an approximate location for the pipe. Holding the PCMx receiver upright at your side, follow the guidance arrow to cross the path of the pipe. Proximity to the pipe is indicated by a rising bar graph and an increase in tone when volume is switched on.
Pinpointing defines the exact position and direction of a pipeline after its position is approximately known. Pinpointing is important as the depth and current readings are affected by misalignment errors.
1. Adjust the receiver sensitivity to approximately 50% by pressing the andkeys. This enables changes in the bar graph to be more readily seen.
2. Hold the PCMx upright and near to the ground.
3. Move it slowly from side to side and define the point of maximum response by looking at the bar graph. The guide arrows should be at minimum length.
4. To align the PCMx with the pipeline, rotate the receiver until the compass is in the 6 O’clock position.
The PCMx receiver features TruDepth™, a feature that helps to ensure the accuracy of locate or survey measurements. When the receiver is not aligned correctly with the pipe direction, the depth and current measurements are automatically removed from the display. The measurements will also be removed when the receiver determines that signal conditions are too poor for reliable results.
Having pinpointed the pipe, the PCMx will display the depth of the pipe, (measured to the center of the pipe), and the current of the locate signal. It is now possible, using the guide arrows, to follow the pipeline.
To turn the internal GPS on:
1. Press the key to enter the menu.
2. Scroll to the GPS menu using the orkeys.
3. Press the key to enter the GPS menu.
4. Scroll to INT to select internal GPS.
5. Press the key twice to accept your selection and return to the main operation screen.
6. When a GPS lock has been acquired the GPS lock symbol will display on the screen. An indicator of the number of satellites in view is also given.