Developing a Measurement System to Test Tractor and Coal Shearer Arms

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"By using NI hardware and LabVIEW, we developed and delivered the control and measurement system in six months. The flexibility of this solution made it possible to adapt the system instantly during the time of the project."

- Bogdan Iwiński, Veritech Sp. z o.o.

The Challenge:
Creating a laboratory to test various parts of mining machinery drives, particularly machines manufactured by KOPEX, using several test stands and detecting flaws during installation of individual components.

The Solution:
Using the PXI and NI CompactRIO platforms and NI LabVIEW system design software to provide conditions similar to those encountered underground and ensure adequate power supply and an efficient cooling system.

Author(s):
Bogdan Iwiński - Veritech Sp. z o.o.
Daniel Kwieciński - KOPEX-EX-COAL Sp. z o.o.
Marek Kostka - KOPEX Machinery S.A.

One Hardware System for Different Tests

The KOPEX Company built an engine test house in connection with the Automated Longwall Control System project. The company arranged several autonomous test beds inside the building. For research purposes, KOPEX simulated the natural conditions in which the coal shearers work. The platform also needed to test various prototype solutions in the future.

The system required a connection to the gear test stand to conduct heat tests. The engine test house could test machines weighing up to 25 tonnes. Users could select voltages of 1 kV, 3.3 kV, and 6 kV for a total power of 3,000 kVA.

The operator could run the test stand manually with buttons on the control cabinet after setting test parameters or through the provided dedicated software.

The types of gears tested include:

  • Cylindrical and intersecting axis conventional gears with up to 2,300 kW of power
  • Cylindrical and intersecting axis planetary gears with up to 2,300 kW of power

The system supports the following measurements:

  • Power
  • Power quality in supply systems
  • Torque
  • Gear shaft velocity
  • Gearing kinematic pair temperature
  • Vibration level
  • Thermography to study heat distribution of selected areas
  • Mesh operating tracks
  • Operating gear noise level

The gear test program depends on the adopted test methodology. For brand new gears or gear prototypes, test times can last one week. However, average test time for series production or post overhaul testing is about 24 hours.

We can conduct the required tests with an electrical module load test bed located in the engine test house next to the gear testing station. The power supply and control module (mainly for coal shearers) is the main unit of the mining machine. Its subassemblies generate a lot of heat during operation. Despite the applied cooling systems, we need to check the temperature of the module each time prior to installing the machine.

During testing, a change occurs in the working conditions that are critical for the installed equipment. The manufacturer tests in extremely unfavourable (close to natural) conditions to check the equipment for proper operation and forecast equipment longevity without conducting difficult and expensive test runs in real-world environments. Both the power supply and control modules, as well as the frequency converters supplying the shearer’s haulage motors, require load testing prior to their installation in the shearer.

We designed the frequency converter test bed to enable testing of the frequency converters and shearer drive systems with a single or double inverter. Postproduction tests include checking the correct operation of a manufactured frequency converter under a specific load regime, considering dynamic transient states. Moreover, the operator can run tests and investigate advanced algorithms for controlling the shearer haulage system. A control application with parameter archives and parameter reproducibility options designed using LabVIEW system design software fully supports the frequency converter test bed.

A Flexible Solution for Measurements

The monitoring and control system comprehensively monitors test stands and controls the systems associated with the test stands’ surroundings. Veritech, a National Instruments Silver Alliance Partner and long-term provider of advanced measurement systems using NI technology, developed this system.

Specific measurement equipment and modular construction made flexible setting modification, part of KOPEX’s requirements, possible. PXI industrial computers provide powerful, but efficient, quad-core processors that can control systems as well as perform data acquisition and analysis in real time. Insulated C Series modules connected all signals. We used the NI MXI-Express RIO platform connected to the PXI to implement code in the FPGA.

The conditioning systems allowed for direct connection of signals from thermocouples, PT100 sensors, strain gage bridges, vibration sensors (IEPE), current signals up to 1 A, and voltage signals up to 300 V. This combination helps us quickly acquire dynamic signals up to 250 kHz per channel and high-resolution measurements up to 24 bits. We also used controller area network (CAN) and ModBus digital data transmission to communicate with the drives via the CAN bus. When the measurement system is being fully used, it can record more than 1 terabyte of data per day.

Using the NI platform, we developed the control module of the three-phase power supply systems and the power quality monitoring. We programmed the NI CompactRIO controllers with LabVIEW and the NI LabVIEW Electrical Power Suite, which creates applications that support electrical measurements. We used the real-time system with the FPGA to acquire and analyze the tested parameters such as level of voltage and current; frequency; active, reactive, and apparent power; phase shifts; and voltage harmonics.

All parameters related to power quality are identified with the software in accordance to relevant International Electrotechnical Commission (IEC) standards, which allow the user to extend the number of measured parameters in the future, depending on the needs of the test stand. KOPEX can optimize operation of the engines and power systems by conducting these tests, which helps the company distribute more efficient and competitive solutions to the world markets.

One LabVIEW Program for Many Tasks

Veritech also developed software so the operator can centrally control the test stand. We mutually synchronised all the data obtained from measurement modules to ensure data integrity. We also analyzed prospective data based on analysis using advanced algorithms, including vibration analysis conducted with the NI Sound and Vibration Measurement Suite and NI DIAdem data management software. The operator could monitor each test bed independently, tracking real-time measurements. We delivered 17 applications running on multiple hardware and system platforms, including Windows, real time, FPGA, and an iPad.

The control system supports the process of mounting sensors directly on objects being tested through mobile devices. The installer can track the values being measured on the installed sensors on the iPad attached to the metal body. Mounting the equipment is efficient because of mobile desktops with sensor connections.

Conclusions

We can test machinery and equipment on an unprecedented scale in the mining industry with the engine test house. By using NI hardware and LabVIEW, we developed and delivered the control and measurement system in six months. The flexibility of this solution made it possible to adapt the system instantly during the time of the project implementation.

The quality of the products the KOPEX Group manufactures will increase with these detailed tribology and compatibility tests. This system will help product verification with regard to product lifecycle management. Using test beds for shearer ranging arm gears, shearer haulers, AFC drive gear, and roadheader gears, the user can conduct several types of tests to detect defects during the assembly of the individual components. We designed the power supply and control systems to accurately reproduce the actual conditions underground in a mine with regard to the operating load dynamics of the tested gears. For research purposes, we also needed to simulate the physical phenomena of the coal mining process. We can test in simulated conditions, which were previously unobservable due to the difficult circumstances in underground work, with high-precision measurements and the number of measured parameters.

Author Information:
Bogdan Iwiński
Veritech Sp. z o.o.
ul. Szyb Walenty 26a
Ruda Śląska 41-700
b.iwinski@veritech.pl

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