Synchronous generator selection scheme with capacity of 6000kV and above

1) 1 year or minor repair

2) Before and after overhaul

1) The insulation resistance value is specified by itself. If the insulation resistance value falls below 1/3 of the normal value of the previous year under similar test conditions (temperature, humidity), the cause should be ascertained.

2) The difference between the insulation resistance values ​​of each phase or each branch should not exceed 100% of the minimum value.

3) Absorption ratio or polarization index: the absorption ratio of asphalt dipping and baking mica insulation should not be less than 1.3 or the polarization index should not be less than 1.5; the absorption ratio of epoxy powder mica insulation should not be less than 1.6 or the polarization index should not be less than 2.0

1) Using 2500V megger, the range is generally not less than 10000MΩ

2) Recommended measurement polarization index for units of 200MW and above

3) The inner cooling stator winding should be carried out under the influence of eliminating residual water, otherwise it will be self-regulated.

4) The inner cooling stator winding of the water uses a special megohmmeter in the case of water flow, and simultaneously measures the insulation resistance of the water conduit and the insulated water conduit.

b. Does not occur outside the high potential and low potential

C.3～10kV valve arrester does not work

5) before preventive testing or every 3 years and when necessary

Check the value/value and verify the thermal stability of the device grounding down conductor.

1) During overhaul

2) When necessary

The DC resistance values ​​of the phases or branches of the turbine generator are compared with each other after correcting the error caused by the difference in the length of the lead wires, and the difference between the initial and the factory measurements is not greater than the minimum value of 1.5. % (1% for hydroelectric generators). If the request is exceeded, the cause should be ascertained

1) In the cold state, the difference between the surface temperature of the winding and the ambient air temperature should not exceed ±3 °C.

2) When the difference between the phases (or branches) of the turbine generator and its relative change over the years is greater than 1%, attention should be paid.

3) For the detection of poor joint quality, see DL/T6641999 6.1.1

4) If necessary, such as: differential protection action can not completely eliminate the stator failure when the outlet is shorted

1) 1 year or minor repair

2) Before and after overhaul

3) After replacing the winding

4) When necessary

1) The test voltage is shown in the following table:

1) It should be carried out after the shutdown to remove the heat before the contamination.
When in standby mode, it can be done in a cold state. Hydrogen cooling
The generator should have a hydrogen purity of 96% or more after hydrogen charging.
When the hydrogen content after hydrogen is less than 3%, it is strictly prohibited to replace
Testing in the process

2) The test voltage is increased in stages of 0.5Un per stage, each
Stage stay 1min

3) Those who do not meet the requirements of 2), 3) should do their best
Can find out the cause and eliminate it, but it can't run

4) When the leakage current increases disproportionately with the voltage,
Should pay attention to analysis

5) When testing, the micro-ampere meter should be connected to the high pressure side and
The surface of the wire sleeve is shielded. Water inside cold generator water supply
If the pipe is insulated, it shall be connected by low-voltage shielding method; if the water pipe is directly grounded, the test shall be carried out under the conditions of no water and water pipe blowing. The cooling water quality should be transparent and pure, without mechanical impurities. The conductivity is required at a water temperature of 25 ° C: no more than 5.0×102 μS/m for open water systems and 1.5×102 μS/m for independent closed circulating water systems.

6) When necessary; if there is a single-phase grounding or differential protection action of the stator winding and the stator failure cannot be completely eliminated

Replace the stator all
After winding and repairing

3.0Un

Partial replacement of the stator
After winding and repairing

2.5Un

Big
repair
before

Those who have been running for 20 years or less

2.5Un

Direct connection to overhead lines for more than 20 years

2.5Un

It has been running for more than 20 years and is not directly connected to the overhead line.

(2.0Un~2.5Un)

Minor repairs and after overhaul

2.0Un

2) Under the specified test voltage, the difference of leakage current of each phase should not exceed 100% of the minimum value; if the maximum leakage current is below 20μA, the phase difference should not change significantly compared with the previous test results.

3) Leakage current does not increase with time

1) Before the overhaul

2) After replacing the winding

1) The test voltage after all stator windings are replaced and repaired is shown in the following table:

1) It should be carried out after the shutdown to remove the heat before the contamination. When in standby mode, it can be done in a cold state. The test conditions of the hydrogen-cooled generator are the same as those in the serial number 3 of this table.

2) The water-cooled motor should generally be tested under the condition of water supply. The imported unit is in accordance with the manufacturer's regulations, and the water quality requirements are in accordance with the relevant regulations.

3) The test voltage during the process of replacing the stator windings in whole or in part can be found in the relevant regulations.

Rated voltage V

Test voltage V

6000～18000

2Un+3000

18000 or more

By special agreement

2) The test voltage after the overhaul or partial replacement of the stator windings and repairs is as follows:

Those who have been running for 20 years or less

1.5Un

Direct connection to overhead lines for more than 20 years

1.5Un

Not connected to overhead lines for more than 20 years

(1.3 to 1.5) Un

1) Minor repair time

2) Before and after the rotor is cleaned during overhaul

3) When necessary

1) Generally not less than 0.5MΩ at room temperature

2) The water cooled rotor winding should not be less than 5k at room temperature.

1) Measurement with a 1000V megger. Water inner cooling rotor
Use 500V and below megohmmeter or other measuring instruments

2) For a hidden pole motor below 300MW, when the stator
The winding has dried and the rotor winding has not dried.
If the insulation resistance of the rotor winding is not small at 75 °C
Allowed to operate at 2kΩ or at 20°C at 20°C

3) For hidden pole motors of 300WM and above, the rotor
The insulation resistance of the winding is 10 ° C (not less than 0.5 MΩ at 2 to 30 ° C)

4) When necessary, such as: after the exit short circuit

1) Minor repair time

2) When necessary

Results measured with the first time (transfer or overhaul)
Comparison, at the same temperature, the difference is generally no more than 2%

1) Measurement in the cold state

2) The pole-type rotor winding should also be placed between the pole coils
Connection point for measurement

3) When necessary, such as: after the exit short circuit

1) When the pole-type rotor is overhauled and after the winding is replaced

2) After the hidden pole rotor is removed from the hoop, the inner part of the tank is insulated and the winding is replaced.

Test voltage is shown in the table below

1) When the hidden pole rotor removal ferrule only repairs the end insulation, it can be replaced by 2500V megohmmeter insulation resistance.

2) If the hidden pole rotor has an aluminum saddle at the end, the voltage resistance test of the winding on the aluminum saddle is performed after the ferrule is removed. Connect the rotor winding to the shaft during the test and apply a voltage of 2000V to the aluminum saddle.

3) The test voltage value during the process of replacing the rotor windings is as specified by the manufacturer.

After the poles and the hidden pole rotors are all replaced and repaired

The rated excitation voltage is 500V and below, 10Un, but not less than 1500V; for 500V or more, 2Un+4000V

When the pole-type rotor is overhauled and the winding is partially replaced and repaired

5Un, but not less than 1000V, no more than 2000V

After the hidden pole rotor is partially repaired in the slot and after the winding is partially replaced and repaired

5Un, but not less than 1000V, no more than 2000V

Overhaul

1) Impedance and power loss values ​​are self-regulated

2) Under the same test conditions, there should be no significant changes compared with the calendar year values.

1) The hidden pole rotor is inside or outside the raft and different turns
Speed ​​measurement. Pole-type rotor for each rotor winding
measuring

2) Each test should be under the same conditions and the same voltage
Under the test, the peak value of the test voltage does not exceed the rated excitation power (the erect rotor is self-regulated)

3) This test can be replaced by dynamic inter-turn short circuit monitoring