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Cold and Hot Run-In Test and Function of Diesel Generator Set

May 25, 2023 | Technical Literature | 0 comments

Before the newly installed or overhauled diesel generator set is put into normal operation, the surface of the parts is not smooth because the engine parts are new or continue to be used after repairing. If these parts are assembled and operated under high temperature, high pressure, high speed and full load immediately, the abrasive wear of the clearance fit part will occur rapidly, thereby shortening the service life of the diesel engine. Therefore, running-in and debugging must be carried out after assembly of newly installed or overhauled diesel generator sets.

1.The Role of Running-In.

Through running-in, to eliminate the rough surface formed during the machining of the parts, reduce the unit pressure on the surface of the worn parts, so that the surface of the matching parts can be in better contact; The resulting geometric deviation. Therefore, after running-in, the wear resistance and corrosion resistance of engine parts are enhanced. Through commissioning, it is possible to check the quality of the engine (after repair), its working condition and make necessary adjustments to some parts. Therefore, running-in and debugging are indispensable steps in the process of generator set installation and overhaul. Familiarity with its operation method is one of the most basic skills that must be mastered by generator set maintenance personnel.

2.Break-In Type.

The running-in of the generator set mainly refers to the running-in of the diesel engine. The running-in of diesel engine is divided into cold running-in and hot running-in.

  • Cold Run-In

Refers to the operation of the crankshaft driven by the electric motor or other power on the test bench of the diesel engine to achieve the purpose of running-in the crankshaft connecting rod mechanism, gas distribution mechanism and other clearance fit parts.

  • Hot Run-In

Refers to the installation of the diesel engine, and after a detailed inspection, the machine is started, and the engine is further inspected and adjusted through no-load and load tests to make it have good power and economy.

Finally: The cold running-in is generally carried out by the manufacturer or the generator set overhaul unit with better conditions. For ordinary users, it is enough to master the hot running-in test of the generator set.

3. Thermal running-in test.

Thermal running-in is divided into two types: no-load test and load test.

1. No load test

The purpose of the no-load test is to check whether there is any fault when the diesel engine is working. Specifically, there are the following points.

  • Check the assembly condition of the machine parts and whether the clearance between the mating parts is appropriate.
  • Check for three leaks (oil leak, water leak and air leak).
  • Is the engine running evenly.
  • Are there any special noises in pistons, piston pins, crankshaft main bearings and connecting rod bearings.
  • Is the exhaust sound and color normal.
  • Whether the oil pressure and cooling water temperature are normal.
  • Is the valve clearance appropriate.
  • Whether the fuel injection pump and fuel injector work normally.

Before hot running-in, reinstall all assemblies, accessories and instruments of the diesel engine, add enough fuel, engine oil and cooling water; debug all necessary adjustments, such as valve clearance, fan belt tightness, engine oil pressure, fuel injection pressure, supply pressure, etc. Oil time, fuel supply and unevenness of fuel supply to each cylinder, etc., keep the engine in good working condition.

We take a diesel engine with a rated speed of 1500r/min as an example, and its no-load test specification is shown in Table . The stage and time of the no-load test for other rated speed diesel engines are the same, but the speed of each stage is different.

Diesel engine no-load test specification

StageTime/minRotating speed/(r/min)
1 (low speed)30800
2 (medium speed)301200
3 (high speed)601500

2. Load test.

The purpose of the load test is to measure the quality of a newly installed engine or engine after overhaul, and check whether the specified technical standards are met.

We still take the oil engine with a rated speed of 1500r/min as an example, and its load test specifications are shown in the table. Diesel engines with other rated speeds are loaded.

Diesel Engine Has a Load Test Specification

Stageload/%Time/minRotating speed/min
1/2/325/50/7530/40/60No load: voltage 400V, frequency 51Hz
Loading: voltage 380V; frequency around 50Hz
That is, the speed should be around 1500r/min
4/5/6100/110/10090/5/10No load: voltage 400V, frequency 51Hz
Loading: voltage 380V; frequency around 49Hz
That is, the speed should be around 1500r/min
7/875/2520/10No load: voltage 400V, frequency 51Hz
Loading: voltage 380V; frequency around 50Hz
That is, the speed should be around 1500r/min
NoteDiesel engines with other rated speeds can refer to this specification, and the requirements for the speed of each stage should be obtained according to the relationship between the speed and frequency.

Finally: Note: After the hot running-in test, the valve clearance must be readjusted, the bolts and nuts at the main bearing, connecting rod and cylinder head must be retightened, and the engine oil shall be replaced in time. When the running-in test of the diesel engine is carried out, if the piston, piston pin, piston is broken, cylinder liner and connecting rod bearing, etc. are replaced in order to eliminate the fault, the running-in test should be carried out again. For newly installed diesel generator sets, or limited by equipment conditions after the generator set is overhauled, hot running-in can be carried out directly instead of cold running-in. After the diesel generator set is run-in, the generator set power and fuel consumption rate and other items should be tested in order to accurately identify the (repair) quality of the generator set.

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