It is designed to take one-off and long-term measurements and records of two analogue variables in the terrain. It is particularly suitable for measuring earth potentials and currents and how they change over time, for example in order to assess the need to apply or increase the efficiency of active (cathodic) anti-corrosion protection. It is constructed with IP65 protection to prevent water from penetrating, and it is suitable for use in the terrain.
The variables to be measured may be two voltages, voltage and current, voltage and resistance, or current and resistance. Direct-current or alternating voltage or current may be measured. The built-in automatic range modifier ensures that measurements are taken with adequate resolution across a wide range of input variables. The maximum range for measuring voltage is 20V, for current 200mA, and for resistance 2MΩ. The recorder is capable of highly precise measurements (0.8-1% MH + 0.2-0.5% MR, depending on the range). For more information see [1].
The recorder does not have any controls (button, display); it is controlled using a mobile computer. In this application a MC9090 mobile computer –9000 series was used, manufactured by SYMBOL. When the mobile computer is connected, the measurements can be displayed directly and the recorder used as a universal measuring device.
Depending on the particular type of measurement, the metal construction (pipe) to be measured is connected via the measuring cable to either the appropriate measuring probe (reference electrode Cu/CuSO4, Fe sample) or to the reference electrodes (polar measurement). When the measurement is complete, the resulting data is transferred from the MEg20 recorder to the mobile computer, so the MEg 20 recorder can also be used to take measurements at other sites. Upon returning to the PC, the data from all the measurement operations stored in the GASACOR2MOBILE application on the mobile computer is transferred to the GASACOR2 application on the PC.
If the MEg20 recorders are to be used immediately at another measuring site, they need to be charged using an external battery source to charge the internal battery. The batteries in the MEg20 last for a maximum of 30 hours of measurement when fully charged.
The MEg 20 twin-channel recorder contains two input amplifier channels with a high input resistance of 10MΩ which, by switching amplification, allow the range to be automatically changed depending on the size of the voltage measured.
When measuring currents, the current to be measured passes through a parallel resistor. The voltage on this parallel resistor is read by one of the voltage channels. When measuring higher currents than the maximum range of 200mA, the current is measured via an external parallel resistor.
For measuring resistance, the Meg 20 recorder is equipped with a power supply. The resistance measurement mode can be used to check cables or to measure transfer resistance between contacts. The MEg 20 recorder is not suitable for measuring the resistance of insulation joints, as the measurements are affected by the alternating current voltage of 50Hz and higher harmonic voltages.
One important construction feature is the IP65 level of protection, which has been applied everywhere, including the input connectors. Microbucaneer connectors are used here. When using the MEg20 measuring device, it is essential to always screw on the covers of the connectors in order to maintain protection levels. If this is not done, the protection is broken.
The MEg 20 twin-channel recorder has been calibrated in ČMI and issued with a calibration certificate confirming the accuracy of its specifications, including measurement accuracy. The new application fully respects current operational experience, making it compliant with the modern conditions expected by operators and allowing the development of modern measuring methods.
Diag.1. MEg20 and accessories
Mobile Data Collesction Device
The MC9090, produced by SYMBOL, was chosen to operate the MEg20 recorder. The MC9090 mobile computer is a durable instrument designed for industrial use, for collecting data in the terrain, and is particularly ideal for reading gas consumption and supporting the work of service technicians. In addition to being used as a terminal, the MEg20 can also be used in other applications within the gas industry.
- The application for the Windows Mobile platform is user-friendly and can also be transferred to other devices, such as a PDA with a Windows Mobile 5.0 OS. The device works like a standard portable computer.
- The mobile computer allows a much wider range of components to be connected, supports WI-FI technology, offers the option to connect it to a PC via USB, connection of GPS, etc.
- In order to unify the methods used to measure corrosion on a nationwide scale, it is best to opt for standardized, advanced equipment from a producer with many years of experience in manufacturing industrial applications
Diag. 2. MC9090 mobile computer
For the parameterization of the MEg20, any mobile computer that meets the following conditions can be used:
· Windows Mobile 5.0 operating system.
· The operating system must include .NET Compact Framework 2.0
· The mobile device must have one USB port or other facility for communicating with a PC and also one serial port for communicating with the MEg20.
· It should also be possible to connect the mobile device to the PC and the MEg20 simultaneously.
Other Possibilities for the Development of the Application
Using a Bar Code
If the measuring points along the routes have a bar code, the application is much simpler. The measurement technician would just read the bar code at the measurement site and would then use this to himself find the point in the list of measuring points. As the MC9090 contains a built-in bar code reader, there would be no need for extra HW.
Using GPS
One possibility is the use of GPS. RWE currently requires that its measurement equipment comply with accuracy class 3. Standard GPS systems do not have this level of accuracy. In this case it would be necessary to use GPS specially calibrated by a laboratory or use other solutions available. GPS is not suitable for measuring new measuring points and entering them in the database.
GPS could be used to search for facilities that are already in place. When approaching the measurement point, the position of the point to be measured could be located on a list based on the position as known and recorded in the database.
