Imagine being able to predict and resolve a maintenance issue before it occurs. With GE Aeroderivative and Package Services’ (GE APS) on-line remote diagnostics system, no crystal ball is needed. Instead customers can rely on this system for ongoing analysis of key operating data of GE LM aeroderivative gas turbines.

The remote diagnostics system is an extension of GE’s service and support activities. GE can electronically visit customer sites whenever necessary, beginning at the critical start-up phase, through to ongoing operations. Periodic data downloads update the system’s database for automated diagnostics, manual trending and investigation purposes. By closely monitoring this data, emerging issues can be detected and proactive measures can be taken to avoid or reduce downtime.

Remote diagnostics customers with GE contractual services agreements in place benefit by making operating data instantly available to GE’s global service network. This means on-site support for troubleshooting is lessened, technical support responsiveness is improved and outage planning is optimized.

GE has experienced success with the remote diagnostics system over the past few years that has helped the entire LM gas turbine fleet, especially those units equipped with GE’s Dry Low Emissions (DLE) system. This day-to-day support for troubleshooting and ongoing DLE mapping has helped improve unit availability.

For example, over the past three years, GE’s monitoring of more than 400 000 fleet operating hours has resulted in four days average downtime reduction per gas turbine per year, and two notifications averaged per gas turbine per year from GE’s Remote Monitoring Centre in Evendale, Ohio, USA.

The remote diagnostics offers customers numerous benefits. For example, global on-line monitoring by all GE service networks enables remote assistance to sites, and many faults can be diagnosed and corrected without a site visit by GE service representatives and engineers. Monitoring larger fleets provides faster learning, resolution and diagnostics development which can reduce future down times.

The system also includes factory assistance to on-site personnel to speed up the DLE gas turbine control mapping processes.

Customers also have access to historical operating data through the remote diagnostics system. This means faster, more detailed investigations, which can translate into decreased site personnel to assemble and forward data to GE. The most recent data is available immediately, and archived data can be accessed within a day.

The remote diagnostics system has been utilized in many different applications throughout the US and Europe:

  • Two DLE LM6000 gas turbines at a cogeneration facility in the US were observed with the remote diagnostics system and were found to be operating for long periods of time with excessive exhaust gas temperature levels. An investigation indicated that the turbine control system was not properly limiting operating levels. The operator was alerted to manually limit the exhaust gas temperatures until modifications were made to the control software. This adjustment helped prevent the turbine overheating.
  • A DLE LM6000 gas turbine at a cogeneration site in Europe was unexpectedly experiencing power reductions. Slow in developing, on-site trending data failed to offer enough detail to suggest a cause. GE’s remote diagnostics system provided the data and investigative tools to assess subtle shifts in the fuel system. The remote diagnostics system identified the problem as a deposit of trace elements from the fuel on the fuel metering valve throat. This caused a gradual decrease in the throat area under certain fuel temperature conditions.

Modifying field operating procedures helped to avoid further power reductions and the accompanying unavailability penalties. Modelling of the historical data confirmed that the proposed solution would solve the problem, and ongoing data collection from modified sites validated the resolution. The availability of the detailed historical data within the monitoring and diagnostics database allowed GE engineers to forego special on-site testing to identify the root cause, and avoid costly and time-consuming factory simulation testing.

  • An LM1600 gas turbine at a compressor station in Canada experienced issues with control system logic, causing a cycling of fuel control hardware. However, no symptoms were displayed to site operating personnel. Through the remote diagnostic systems, engineers discovered the problem and dispatched field service personnel to correct the issue. This was done prior to any hardware failures or before a protective trip could cause a forced outage.
  • Using analysis of temperature profiles, diagnostic engineers were able to identify the most likely fuel nozzles to be clogged in an LM6000 gas turbine operating at a Canadian cogeneration plant.

System characteristics

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Customers use an On-Site Monitor (OSM) for each gas turbine site to gather operating data and to provide a communication interface with the Remote Monitoring Centre in Evendale. More than 1000 parameters can be monitored on each gas turbine, including variable data from sensors and controls, and status data such as alarms, trips and equipment on-off conditions (see Table 1).

The OSM is electronically linked to the site’s gas turbine control system and can be connected to site vibration monitors, allowing remote viewing and analysis of vibration signals. OSMs can be installed by the gas turbine packager at the factory, or by field technicians on-site.


Figure 1. Customers use an OSM for each gas turbine site to gather operating data and to provide a communication interface with the Remote Monitoring Centre
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It continually archives the parametric data for frequent retrieval and analysis. This data is used to evaluate the mechanical health of the gas turbine in order to avoid forced outages, minimize outage downtime and reduce the extent of repairs needed.

To ensure the customer gets accurate results, GE periodically updates its database of operating data for every gas turbine in its diagnostics fleet. By applying statistical tools to this time-based update, GE can identify abnormal changes in engine performance that may indicate a fault or site issue.

The future

GE is continually improving its remote diagnostics capabilities in order to ensure satisfaction for its customers. It is looking to improve upon the OSM model and already has plans to upgrade.

It is currently adding an automated notification of critical events system in which logic engines reside in the OSM system, and an auto-dial to the Monitoring Centre upon detection of critical faults and trends. The system also includes auto-paging to key support personnel.

A generator set monitoring system will monitor the generator, gas turbine auxiliaries, and enclosure equipment.

The remote diagnostics system will also provide a private customer website on the internet so information regarding on-site data can be easily located in GE’s database.

The internet site will allow remote on-line viewing of operating equipment, and give the customer the ability to standardize and customize reports.

Wireless remote status checks which will allow the customer to instantly download the status of key parameters using wireless PDA will also be included in the upgrades.

Availability

GE currently offers this on-line support free of charge to operators of most models of its LM aeroderivative gas turbines during the warranty period. For those customers whose equipment is out of warranty, the on-line service may be purchased or included as part of contractual services agreement.

Control system requirements for transmission of gas turbine and package operating parameters vary with LM gas turbine model and package design. GE APS will coordinate with the operator’s staff to define controls configuration and on-site installation details.