To test the short circuit characteristics of the generator, not only the short circuit characteristic curve can be measured, but the synchronous reactance and short circuit ratio of each generator can be obtained. In power plants, it can be used to determine whether there are inter-turn shorts in the rotor and stator windings and other related component failures.
For new units, testing of the generator's short circuit characteristics should be performed. For units that have been put into production, testing of the generator's short circuit characteristics is rarely performed, so it is not often encountered. Even if it is overhauled, if there is no abnormality in the transformer, it is difficult to do a short circuit test.
Coincidentally, I recently encountered a short circuit characteristic test of a generator during the debug phase of thea gas turbine. Since the generator differential protection band load test is usually performed during this testing of a new unit, it was once thought that when the generator undergoes a short circuit test, the generator differential protection must be off service, as does the protection of the generator transformer. . Recently, a colleague asked a question about this, and after careful consideration, if one simply performs a short circuit characteristic test of the generator, it is indeed not necessary to remove the differential protection of the generator.
Generally, when a generator is short-circuited, an aluminum bar with current-carrying capacity meeting the requirements is used to short-circuit the three-phase output wire of the generator stator and the ground. there is a switch at the generator output, a shorting bar is sometimes connected to the output of the igenerator switch. After the preparation is ready, adjust the full-speed excitation current of the unit, carry out rising and falling short-circuit characteristic tests, and compare the relationship curve between the stator steady-state short-circuit current and the excitation current when the stator is short-circuited in three phases.
Protection requirements during short circuit testing are as follows: Protection that may malfunction should be removed. I checked the protection removal status of the unit after a major overhaul in 2003: when the generator output voltage change and neutral point voltage change were removed, the generator differential, the symmetrical overload of the generator and the generator was put into reverse overcurrent, grounding of the rotor point. , generator water cutoff protection (water-hydrogen-hydrogen group), and other protectionoutput sections of the generator-transformer group.
Notes on testing short circuit characteristics: (1) Take the reading of the standard instrument connected to the secondary circuit of the generator as the standard. Refer to the daily instrument. If there is a significant deviation, stop the test and find out the cause. (2) During the test, when the excitation current reaches 15-20% of the rated value, the three-phase current balance of the stator should be checked and it should be normal. (3) Temporary wiring must be standardized.
Should the 300KW emergency diesel generator be started regularly?
What should be included in the generator no-load drag test:
Diesel generator set no-load test Machine test, detect manual and automatic start and stop functions, simulate and detect high water temperature, low oil pressure, overspeed, send signals alarm and arrbe normal. When the diesel generator set is subjected to a false load (burn-in) test, the diesel generator set operates at 25% load for 10 hours, 50% load for 15 hours, and 80% load for 25 hours. hours At the same time, the diesel generator set is tested under different operating conditions. After the output voltage, current, frequency, water temperature, oil temperature, exhaust temperature and instrument display are tested and meet the requirements, the final. the inspection can be carried out after three months of testing.
The diesel generator has automatic and manual start functions. The diesel generator can automatically start, automatically switch, automatically operate, automatically send power and automatically stop, etc. Function, the diesel generator set is equipped with protective devices.n against high water temperature, low oil pressure and overspeed. Once the communication hub diesel generator is assembled, the generator insulation test should be performed. The insulation of the armature winding is greater than 2 megohm, the insulation of the field winding is greater than 1 megohm, and the insulation of. the winding of the charging generator is more than 0.5 megohms after the diesel generator set is tested normally. After filling the antifreeze, engine oil and fuel into the oil storage tank according to the instructions of the diesel generator set, the diesel in the oil storage tank must remain stationary for more than 24 hours.
Generator no-load short circuit test sequence
In one sentence you will understand the truth. It takes time to raise an army for a thousand days, not to mention the equipment and. machines According to the production of diesel energy According to the proceduress operation of the unit, the emergency generator should be regularly maintained, inspected and inspected, and no-load and load tests should be carried out regularly. The details are as follows:
1. Perform a no-load test on the generator set every month and record the no-load test parameters
2; . Perform a startup test every quarter. On-load test, the general duration of the on-load test is 30 minutes, and the on-load load is 70% of the generator set's rated power; >3. The specific precautions are as follows:
(1), When the unit is stopped, check whether the appearance of the unit, instruments and cable joints is intact. handle them accordingly;
(2) Perform various inspections before starting the unit. Then manually debug the generator set (including whether the cooling water, fuel, water and oil pipe jointsleaking, etc.) to check whether the unit parameters are normal, then stop the machine, then perform automatic debugging to check whether the unit parameters are normal;
(3) after load test and no load test. Acceptance is complete, perform manual and automatic load tests on the unit. Please read the operating procedures of the generator set and carefully check whether the output parameters of the generator set are normal, is there any abnormality in the sound, etc.
(4). Start part of the load provided by the generator and carefully check whether the load is operating normally.
(5) Check whether the protection performance of the generator set is intact and whether it is safe and reliable.
Short circuit testing is usually performed on newly installed units or after an overhaul. The reason is that the residual magnetism of these units is not ggenerally not sufficient. Automatic excitation is not sufficient to increase voltage. that is, the voltage cannot be increased, so do a short circuit test first to generate sufficient magnetic field. After the test there will be residual magnetism and the voltage can be increased.
In addition, the short circuit test can check the polarity of each current transformer and the correctness of the current loop. The protection of the relay mainly relies on the operation of the CT loop, so the correct CT loop can guarantee the correct operation. normal operation of the protection device. It will be much safer to perform the dry test this way.
My understanding.