Load Rejection Test (LRT) and Reliability Running Test (RRT)

DSC_0221From the last three days, I’m visiting my company project in Sei Gelam, Jambi. This is gas engine power plant project with rated output capacity 90 MW used for peaker condition. I come to this project to take a part in commissioning stage and this is my first experience in commissioning stage for power plant project.

Ok, let me explain a little bit about this commissioning stage.

Load Rejection Test (LRT)

Load rejection test means to test the engine performance with no load condition after running with full load. Simply, the test done to check the engine and generator performance in case generator circuit breaker suddenly trip due to fault in upper network.

The following step to be done for this test:

  1. Make sure fuel system run properly (i.e. air instrument system, gas compressor – if any, control valve, etc.). In this commissioning stage, fuel system supplied from other electrical source.
  2. Activate the engine
  3. Run the engine until 100% capacity
  4. Connect to the existing network
  5. Synchronize the generator output to existing network
  6. Break the generator circuit breaker manually from generator circuit breaker control panel
  7. Check the engine and generator parameter (speed, voltage, current) from OWS
  8. Check all relay protection status
  9. In case there is no relay trip, re-connect to existing network
  10. Synchronize the generator output to existing network
  11. Run the engine with 100 capacity
  12. Continue to Reliability Run Test

The following is the function of this test procedure:

  1. To check the engine performance during the transient condition. In this condition, engine will run in governor mode.
  2. To check the control system ability in synchronous with existing network after no load condition.
  3. To check the generator parameter after breaking the circuit breaker (over  speed, voltage, current and frequency)
  4. To check the function of support system, such as gas pressure, air instrument condition during the tripping time.

What parameter to be consider to pass this stage? only one, no relay trip during the above step!!

Reliability Run Test (RRT)

Procedure for this step to run the engine continuously during the certain time (i.e. gas engine made by Wartsila, normally 50-72 hours). During the engine running, operator should take the data of rated current, rated voltage, rated output, engine speed, frequency and output power factor periodically, normally each 30 minit. After 72 hours, the engine shall shutdown and checked by the mechanic before continue to the next stage.

This was my short experience during the Load Rejection Test and Reliablelity Run Test. If some expert read this, please give an advice for some available mistaken (if any).

Note: this is my first english post in this blog, sorry for my english if confusing you 🙂


10 thoughts on “Load Rejection Test (LRT) and Reliability Running Test (RRT)

    • Hi Saurab,

      Great if this post can help you to understand gas engine commissioning. This only the general procedure. For more detail, normally it depend on the gas engine supplier.

    • Yes, the power plant is already run for almost one years ago actually. The problem occur only during the reliability running stage. For one engine, it should be repeated until 3 times due to problem on fuel gas system.

    • Hi TGM,

      Thank you for your comment and for putting my blog as reference in your website. I already visit your website.
      It was nice if this article helpful for you.

  1. Hi HURRICANE193

    Thanks for your blog as it is helpful to understand the various stages (LRT & RRT) of power plant. Can you pls post some details about Coal Sourcing and Logistics.

    • Dear Mayank Kapur,

      Thank you for your comment. I’m sorry, I don’t have direct experience in coal fire power generation so I can’t provide required information.
      Please just browse on the general knowledge tab and electrical engineering tab for more list of my valuable post.



  2. Nice article in English bro..
    Why shoul we do load rejection test?
    Im my case, The contractor want to do LRT, and the problem is we afraid that our exsisting power plant (4 power plant) can not handle when the system loss power.

    • Thank you.
      Actually this test required to test the driven equipment behavior on the new power plant. Especially on speed of the driven equipment during lost power, in normal case during lost power driven equipment speed will increase. If the speed continue increasing and pass allowable limit, the driven equipment will trip. For such case, the load rejection test result is fail. Therefore, speed control required to maintain this speed during lost power (load rejection test) and this device is tested during the commissioning stage to assure it work properly.
      For your case, could please provide more data? Such as peak load of the system, capacity of each power plant (existing), capacity of new power plant?
      Normally we perform this test during low demand hour (normally from 7.00 am to 5.00 pm).

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