[No.1 Generator Stator Winding AC Withstand Voltage Test Plan]

#1 Generator Stator Winding AC Withstand Voltage Test Plan

1. #1 Generator Basic Parameters

Model: 50WT21E—106< /p>

Rated capacity: 415MVA

Rated power: 352.75MW

Rated voltage: 20KV

Rated current: 11980A

Frequency: 50Hz

Power factor: 0.85

Rated speed: 3000г/min

Cooling method: water hydrogen hydrogen

Excitation method: static excitation

2. Purpose of the test

This test is a pre-revision test. The purpose is to determine the insulation level of the generator stator winding and check for insulation defects.

3. Test basis

GB755-2000 ("Rating characteristics and performance of rotating electrical machines")

GB/T7064-2002 ("Technical requirements for synchronous turbine motors")

4. Test conditions

? DemaSubmit generator work tickets and return other business work tickets at the same time.

? The generator gas replacement is complete and the rotor is in the stator bore.

? The cold water in the generator is put into normal operation and the water conductivity meets the operating standards, but is as low as possible. ? Generator insulation resistance test passed.

? All temperature clamps should be removed and measuring points and other components should be shorted to ground to prevent damage during testing. ? Before testing, test the generator capacity and check the compensation inductance.

? Ground the generator rotor and seal mother, and short the current transformer to ground.

? The ball spacing discharge voltage adjustment is qualified and the protective water resistance ist selected appropriately.

? Release the power switch leakage protection.

5. Test method

The test wiring diagram is shown in Figure 1. Considering the power supply capacity limitations of on-site testing, a reactor (connected to the generator side under test) must be used for reactive power compensation. Choose four reactors of 35H and 20KV, two in series and two in parallel. The reactance value after parallel connection is 35H. Apply a voltage of 30KV in accordance with regulations.

6. Test steps:

1) After inspection and confirmation that the tested product, insulation resistance and internal cooling water quality meet the requirements, the conditions of the AC withstand voltage test will be met.

2) Remove or disconnect all connections connected to the test object and take all safety measuressafety in accordance with the relevant provisions of the safety regulations.

3) Check the test wiring according to the wiring diagram, it should be correct, the test equipment should be reasonably arranged, easy to operate, and comply with the relevant provisions of safety regulations. Protective earthing must be firm and reliable.

4) Check that the test equipment and measuring instruments are intact, placed stably, and the zero position is correctly adjusted.

5) CheckThe test can only be started after checking that everything is correct. The voltage increase starts from zero and slowly increases to the specified test voltage value. It lasts 1 minute and the voltage remains stable during the withstand voltage duration. Once the time is up, slowly lower the voltage.

7. Safety precautions

a) After inspection, it is confirmed that the product tested and the resistance testinsulation stance have passed the test.

b) Strictly implement the relevant provisions of DL408-91 “Safety working procedures for the power industry (electrical parts of power plants and substations)” and relevant safety measures on site .

c) Staff members have a clear division of labor and responsibilities and are focused on their work.

d) Install safety barriers on site, hang signs, prepare necessary fire-fighting equipment and maintain sufficient distance between the pressure point and the sealing block.< /p>

e) There are dedicated personnel to monitor the test site and generator platform to monitor the tested products and confirm whether there are any abnormal sounds.

f) During the test, the product under test exhibits breakdown noises (or intermittent discharge noises), smoke, outgassing, smell ofburnt, arcing, combustion, etc., stop testing immediately and further identify the cause.

g) During the test, record the ambient temperature and humidity, as well as the generator outlet water temperature.

h) Restore all measurement signal loop wiring after testing.

i) The insulation of the generator stator winding shall be measured before and after the test.

8. Main test equipment

1 set of 30KVA/30KV test transformer

4 sets of compensation reactor 35H, 20KV/2A

AC CVD-100 1 digital kilovoltmeter

1 thermometer and hygrometer

1 ball gap (approximately 12 mm)

2 resistances water

1000mA mA meter 1 piece

5A ammeter 1 piece

Prepared by: Wuhu Power Plant 2006.10.25

Attached Figure 1 #1 Generator AC Withstand Voltage Test Wiring Diagram How to Measure Motor Insulationof the 380 V water pump? How good is the insulation?

Starting the excitation motor generally does not require water resistance. Excitation motor mainly refers to the motor used to drive the generator. The excitation motor excites the generator to generate current. During the starting process of an excitation motor, an external power supply is usually used to power the motor without the need for a water distribution resistor.

Water distribution resistors are mainly used in hydraulic transmissions or hydraulic transmission devices in hydraulic systems to adjust the flow and pressure in the hydraulic system. It performs variable speed or power transmission operations by changing the oil flow path or limiting the flow rate.

Therefore, under normal circumstances, startupof the excitation motor does not require water resistance. This view is based on a general understanding of field motors and hydraulic transmissions, but care should be taken to determine the specific situation.recognize.

Use a 500V or 1000V megger to measure. If the insulation resistance is 0.5MΩ or more, it is qualified.

A megger, also known as a megger, is an instrument used to measure the insulation resistance and high value resistance of equipment under test. It consists of a hand-cranked generator, a meter head and three. terminals (i.e. L: line end, E: ground end, G: shield end).

Before measuring, perform an open circuit and short circuit test on the megger to check whether the megger is in good condition. If both connecting wires are open and the handle is shaken, the pointer should point to∞. (infinity). Momentarily short the connection head and the pointer should point to 0. At this time, it means the meter is good.

Connect the L terminal (line end) of the megger to the water pump motor terminal box and connect the E terminal (ground end) of the megger to the water pump motor housing. water.

When measuring, press the meter housing with one hand (to prevent the meter from vibrating). When the needle indicates 0, stop shaking immediately to avoid burning the meter;

When measuring, place the meter in a horizontal position and turn the generator crank at a speed of about 120 revolutions per minute

The reading after the pointer is basically stable after shaking for about 1 minute, this is the insulation resistance value of the motor.

A megger, also known as a megger, is an instrument used to measure resistanceinsulation and high value resistance of the equipment tested. It consists of a hand-cranked generator, a meter head and three. terminals (i.e. L: line end, E: ground end, G: shield end).

Principles of selection of megohmmeters:

(1) Selection of the rated voltage level. Generally speaking, for equipment with a voltage rating below 500 V, a 500 V or 1000 V megger should be used; For equipment with a rated voltage above 500V, a 1000V~2500V megometer should be used. For equipment with a voltage rating greater than 10 KV, a 2500 V megger should be used.

(2) Resistance range selection. There are two small black dots on the scale of the megger dial, and the area between the small black dots is the precise measurement area. Therefore, when selecting an array, the insulation resistance valuent of the equipment under test must be within the precise measurement area.

3. Precautions for using meggers

(1) The megger should be selected according to the voltage level of the equipment. For low voltage electrical equipment, a 500 volt. The megger must be selected. Using a megger with too high a voltage to measure low voltage insulation may cause insulation breakdown;

(2) Before measuring insulation resistance, the power supply of the equipment under test must be turned off. off and a short circuit discharge must be carried out. The purpose of discharge is to ensure the safety of people and equipment and ensure accurate measurement results;

(3) The connecting wires of the megger should be two separate. single wires (preferably two colors) with good insulation. Do not twist the wires together, and it is best not to put the wires in contactwith ground to avoid errors caused by poor wire insulation;

(4) Before measuring, perform open circuit and short circuit test on the megger, check whether the megger is in good condition. If both connecting wires are open and the handle is shaken, the pointer should point to ∞ (infinity). ). At this time, if the two connecting wires are connected, short circuit momentarily and the pointer should point to 0. At this time, it means that the megger is good, otherwise the megger will have errors;

(5) During measurement, press the watch case with one hand (to prevent the watch from vibrating). When the needle indicates 0, stop shaking immediately to avoid burning the meter;

(6) When measuring, place the meter in a horizontal position and rotate the generator at a speed of about 120 revolutions per minute. handle;

(7) Before the megger stopsrotating or the equipment under test is not discharged, do not touch the measured part and the terminal of the instrument or remove the connection with your hands to avoid electric shock;

(8) If the weather is humid or the insulation resistance of the cable is measured, the shield terminal G (or protective ring) should be connected to eliminate the influence of the leakage current on the surface of the insulation;

(9) It is prohibited to use a megohmmeter to measure the insulation of equipment in lightning or humid weather and when there is high voltage electrical equipment nearby;

( 10) After the measurement is completed, the equipment under test should be unloaded.

4. The role of measuring insulation resistance and judging the resistance value:

Measuring the insulation resistance of electrical equipment is the simplest auxiliary method to check its condition insulation. Insulation resistancemeasured can detect defects such as foreign bodies affecting the insulation of the conductive part of the electrical equipment, moisture and dirt in part or all of the insulation, serious deterioration of the oil insulation, a breakdown of the insulation and significant thermal aging.

(1). The measured insulation resistance must be equal to or greater than the generally permitted value. The specific regulations of various electrical appliances are different: 0.5MΩ for low voltage equipment. 300 MΩ for 3-10 KV and 300 MΩ for 20-35 KV 400 MΩ, 63-220 KV corresponds to 800 MΩ and 500 KV corresponds to 3000 MΩ.

(2) Compare the measured value with the value from the factory, shed and previous years. There should be no significant change from the previous test result, usually not less than 70% of the previous value. .

(3) The absorption rate of 35 kV transformersand more should be measured, which is generally not less than 1.3. (Absorption rate calculation: insulation resistance measured in 60 seconds is better than insulation resistance measured in 15 seconds).