Section 1 General Rules

Norms of acceptance tests. Synchronous generators and compensators

Encyclopedia of radio electronics and electrical engineering / Rules for the installation of electrical installations (PUE)

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1.8.13. Synchronous generators with a power of more than 1 MW and a voltage above 1 kV, as well as synchronous compensators, must be tested in full in accordance with this paragraph.

Generators with a power of up to 1 MW and a voltage above 1 kV must be tested according to paragraphs 1-5, 7-15 of this paragraph.

Generators with voltage up to 1 kV, regardless of their power, must be tested according to paragraphs 2, 4, 5, 8, 10-14 of this paragraph.

1. Determination of the possibility of switching on without drying generators above 1 kV.

Should be produced in accordance with the manufacturer's instructions.

2. Measurement of insulation resistance.

The insulation resistance must not be less than the values ​​given in Table 1.8.1.

3. Testing the insulation of the stator winding with increased rectified voltage and measuring the leakage current by phase.

Each phase or branch is tested separately with other phases or branches connected to the housing. For generators with water-cooled stator windings, testing is carried out if this possibility is provided for in the design of the generator.

The test voltage values ​​are given in Table 1.8.2.

For turbine generators of the TGV-300 type, the test should be carried out along the branches.

The rectified test voltage for generators of the TGV-200 and TGV-300 types is 40 and 50 kV, respectively.

For turbogenerators TVM-500 (Unom=36,75 kV), the test voltage is 75 kV.

Measurement of leakage currents to construct curves of their dependence on voltage is carried out at no less than five values ​​of rectified voltage - from 0,2Umax to Umax in equal steps. At each stage the voltage is maintained for 1 minute. In this case, leakage currents are recorded after 15 and 60 s.

The obtained characteristics are assessed in accordance with the manufacturer's instructions.

4. Insulation test with increased voltage of industrial frequency.

The test is carried out according to the standards given in Table 1.8.3.

Each phase or branch is tested separately with other phases or branches connected to the housing.

The duration of application of the normalized test voltage is 1 min.

When conducting insulation tests with increased power frequency voltage, the following should be followed:

a) it is recommended to test the insulation of the generator stator windings before inserting the rotor into the stator. If the joining and assembly of the hydrogen generator stator is carried out at the installation site and subsequently the stator is installed in the shaft in assembled form, then its insulation is tested twice: after assembly at the installation site and after installing the stator in the shaft before the rotor is inserted into the stator.

During the test, the condition of the frontal parts of the machine is monitored: for turbogenerators - with the end shields removed, for hydrogenerators - with the ventilation hatches open;

b) testing the insulation of the stator winding for machines with water cooling should be carried out with the circulation of distilled water in the cooling system with a resistivity of at least 100 kOhm/cm and a nominal flow rate;

c) after testing the stator winding with increased voltage for 1 minute, for generators of 10 kV and above, reduce the test voltage to the rated voltage of the generator and maintain for 5 minutes to observe the corona of the frontal parts of the stator windings. In this case, there should be no yellow or red glow concentrated in individual points, the appearance of smoke, smoldering of bandages and similar phenomena. Blue and white glow is allowed;

d) testing of the insulation of the rotor winding of turbogenerators is carried out at the rated rotor speed;

e) before putting the generator into operation after completion of installation (for turbogenerators - after inserting the rotor into the stator and installing the end shields), it is necessary to carry out a control test with a rated power frequency voltage or a rectified voltage equal to 1,5 Un. Test duration 1 min.

5. DC resistance measurement.

The norms for permissible deviations of DC resistance are given in Table 1.8.4.

When comparing resistance values, they must be brought to the same temperature.

6. Measurement of the resistance of the rotor winding to alternating current.

The measurement is carried out in order to identify turn short circuits in the rotor windings, as well as the condition of the rotor damper system. For non-salient-pole rotors, the resistance of the entire winding is measured, and for salient-pole rotors, the resistance of each winding pole individually or two poles together. The measurement should be made with an input voltage of 3 V per turn, but not more than 200 V. When choosing the value of the input voltage, the dependence of the resistance on the value of the input voltage should be taken into account. The resistance of the windings of non-salient-pole rotors is determined at three to four speed levels, including the nominal one, and in a stationary state, maintaining the applied voltage or current constant. Resistance across poles or pairs of poles is measured only with a stationary rotor. Deviations of the obtained results from the manufacturer's data or from the average value of the measured pole resistances by more than 3-5% indicate the presence of defects in the rotor winding. The occurrence of turn faults is indicated by the abrupt nature of the decrease in resistance with increasing rotation speed, and poor quality in the contacts of the rotor damper system is indicated by the smooth nature of the decrease in resistance with increasing rotation speed. The final conclusion about the presence and number of closed turns should be made based on the results of taking the short circuit characteristics and comparing it with the manufacturer’s data.

7. Checking and testing of electrical equipment of excitation systems.

Standards for testing power equipment of thyristor self-excitation systems (hereinafter referred to as STS), independent thyristor excitation systems (STN), brushless excitation systems (BSV), and semiconductor high-frequency excitation (HF) systems are given. Checking the automatic excitation regulator, protection devices, control devices, automation, etc. is carried out in accordance with the manufacturer’s instructions.

Checking and testing of electric machine exciters should be carried out in accordance with 1.8.14.

7.1. Measurement of insulation resistance.

The insulation resistance values ​​at temperatures of 10-30 ºС must correspond to those given in Table 1.8.5.

7.2. Power frequency high voltage test.

The value of the test voltage is taken according to Table 1.8.5, the duration of application of the test voltage is 1 min.

7.3. Measurement of direct current resistance of windings of transformers and electrical machines in excitation systems.

The resistance of the windings of electrical machines (auxiliary generator in the STN system, inductor generator in the HF system, inverted synchronous generator in the BSV system) should not differ by more than 2% from the factory data; transformer windings (rectifiers in STS, STN, BSV systems; serial in individual STS systems) - by more than 5%. The resistances of the parallel branches of the working windings of inductor generators should not differ from each other by more than 15%, the phase resistances of the rotating exciters - by no more than 10%.

7.4. Checking transformers (rectifier, series, auxiliary needs, initial excitation, voltage and current instrument transformers).

The check is carried out in accordance with the standards given in 1.8.16, 1.8.17, 1.8.18. For series DC transformers, the relationship between the voltage on the open secondary windings and the generator stator current U2p.t.=f(Ist.) is also determined.

Characteristic U2p.t.=f(Ist.) is determined by taking the characteristics of a three-phase short circuit of the generator (unit) to Ist.nom. The characteristics of individual phases (with single-phase series transformers) should not differ from each other by more than 5%.

7.5. Determination of characteristics of an auxiliary synchronous power frequency generator in STN systems.

The auxiliary generator (AG) is checked in accordance with clause 8 of this paragraph. The short circuit characteristic of the high voltage generator is determined up to Ist.nom., and the idle speed characteristic is determined up to 1,3Ust.nom. with checking the turn insulation for 5 minutes.

7.6. Determination of the characteristics of an inductor generator together with a rectifier installation in an HF excitation system.

Produced with the series excitation winding turned off.

Characteristics of the no-load speed of an inductor generator together with a rectifier unit (RU), [Ust, Uv=f(In.v.), where In.v. - current in the independent excitation winding], determined to the value Uву, corresponding to twice the rated value of the rotor voltage, should not differ from the factory value by more than 5%. The voltage spread between series-connected AC valves should not exceed 10% of the average value.

The short circuit characteristics of the inductor generator together with the control device should also not differ from the factory value by more than 5%. With a rectified current corresponding to the rated rotor current, the spread of currents along the parallel branches in the arms of the control unit should not exceed ±20% of the average value. The load characteristic is also determined when working on the rotor up to Iрхх[Iр=f(Iв.в.)], where Iв.в. - exciter excitation current.

7.7. Determination of the external characteristics of a rotating subexciter in HF excitation systems.

When the load on the exciter changes (the load is an automatic excitation regulator), the change in the exciter voltage should not exceed the value specified in the factory documentation. The voltage difference between phases should not exceed 10%.

7.8. Checking the elements of an inverted synchronous generator and a rotating converter in the BSV system.

The DC resistance of the transition contact connections of the rotating rectifier is measured: the resistance of the current conductor, consisting of winding terminals and feed-through pins connecting the armature winding to the fuses (if any); connections of valves with fuses; the resistance of the rotating converter fuses themselves. The measurement results are compared with factory standards.

The tightening forces of valves, fuses of RC circuits, varistors, etc. are checked. in accordance with factory standards.

The reverse currents of the rotating converter valves are measured in a complete circuit with RC circuits (or varistors) at a voltage equal to the repeating voltage for a given class. Currents must not exceed the values ​​specified in the factory instructions for the excitation systems.

7.9. Determination of the characteristics of an inverted generator and a rotating rectifier in three-phase short circuit modes of the generator (unit).

The stator current Ist, exciter excitation current Iv.v., rotor voltage Uр are measured, and the compliance of the exciter characteristics Uр=f(In.v.) with the factory ones is determined. Based on the measured stator currents and the factory short circuit characteristic of the generator Ist=f(Iр), the correct settings of the rotor current sensors are determined. The deviation of the rotor current measured using a DTR-P type sensor (BSV output current) should not exceed 10% of the calculated value of the rotor current.

7.10. Testing of thyristor converters of STS, STN, BSV systems.

Insulation resistance measurement and high voltage testing are carried out in accordance with Table 1.8.5.

Hydraulic tests are carried out with increased water pressure on thyristor converters (TC) with a water cooling system. The pressure value and the time of its exposure must comply with the manufacturer’s standards for each type of converter. The TC insulation is rechecked after filling with distillate (see Table 1.8.3).

The absence of broken thyristors or damaged RC circuits is checked. The test is performed using an ohmmeter.

The integrity of the parallel circuits of the fuse link of each power fuse is checked by measuring the DC resistance.

The state of the thyristor control system and the range of regulation of the rectified voltage when exposed to the thyristor control system are checked.

The TP is checked when the generator is operating in nominal mode with the rated rotor current. The check is carried out to the following extent:

• distribution of currents between parallel branches of the converter arms; the deviation of the current values ​​in the branches from the arithmetic mean value of the branch current should be no more than 10%;
• distribution of reverse voltages between series-connected thyristors, taking into account switching overvoltages; the deviation of the instantaneous value of the reverse voltage from the average value on the branch thyristor should be no more than ±20%;
• current distribution between parallel-connected converters; currents should not differ by more than ±10% from the average calculated value of the current through the converter;
• current distribution in the branches of the same-named arms of parallel-connected transformer transformers; the deviation from the average calculated value of the current of a branch of the same arms should not be more than ±20%.

7.11. Checking the rectifier diode installation in the RF excitation system.

Performed when the generator is operating in nominal mode with the rated rotor current. When checking, it is determined:

• current distribution between parallel branches of the arms; deviation from the average value should be no more than ±20%;
• distribution of reverse voltages across valves connected in series; the deviation from the average value should be no more than ±20%.

7.12. Checking switching equipment, power resistors, auxiliary equipment for excitation systems.

The check is carried out in accordance with the instructions of the manufacturer and 1.8.34.

7.13. Measuring the temperature of power resistors, diodes, fuses, busbars and other elements of converters and cabinets in which they are located.

Measurements are performed after switching on the excitation systems under load. The temperatures of the elements should not exceed the values ​​​​specified in the manufacturers' instructions. When checking, it is recommended to use thermal imagers; the use of pyrometers is allowed.

8. Definition of generator characteristics:

a) three-phase short circuit. The characteristic is removed when the stator current changes to the rated one. Deviations from the factory specifications must be within the measurement error.

A decrease in the measured characteristic, which exceeds the measurement error, indicates the presence of turn short circuits in the rotor winding.

For generators operating in a block with a transformer, the short-circuit characteristic of the entire block is removed (with the installation of a short circuit behind the transformer). The characteristics of the generator itself, operating in a block with a transformer, may not be determined if there are corresponding test reports at the manufacturer’s bench.

For synchronous compensators without an accelerating motor, the characteristics of a three-phase short-circuit are measured during the freewheel if there is no characteristic taken at the factory;

b) idling. Raising the voltage of the rated frequency at idle to 130% of the rated voltage of turbogenerators and synchronous compensators, up to 150% of the rated voltage of hydraulic generators. It is allowed to take the idle characteristics of a turbo and hydrogenerator up to the rated excitation current at a reduced generator speed, provided that the voltage on the stator winding does not exceed 1,3 rated. For synchronous compensators, it is allowed to take the run-down characteristic. For generators operating in a block with transformers, the idle characteristic of the block is removed; in this case, the generator is excited to 1,15 rated voltage (limited by the transformer). The idle speed characteristic of the generator itself, disconnected from the unit’s transformer, may not be taken if there are corresponding test reports from the manufacturer. The deviation of the idle speed characteristics from the factory one is not standardized, but must be within the measurement error.

9. Test of interturn insulation.

The test should be carried out by raising the voltage of the rated frequency of the generator at idle to a value corresponding to 150% of the rated stator voltage of hydraulic generators, 130% of turbogenerators and synchronous compensators. For generators operating in a block with a transformer, see instructions in paragraph 9. In this case, you should check the symmetry of the voltages across phases. The duration of the test at the highest voltage is 5 minutes.

It is recommended to test the interturn insulation simultaneously with taking the idle speed characteristics.

10. Vibration measurement.

Vibration (range of vibration displacements, double amplitude of vibrations) of generator components and their electric machine exciters should not exceed the values ​​​​given in Table 1.8.6.

Vibration of bearings of synchronous compensators with a nominal rotor speed of 750-1500 rpm should not exceed 80 μm in the range of vibration displacements or 2,2 mm s-1 in the root mean square value of the vibration speed.

11. Checking and testing the cooling system.

Produced in accordance with the manufacturer's instructions.

12. Checking and testing the oil supply system.

Produced in accordance with the manufacturer's instructions.

13. Checking the insulation of the bearing during the operation of the generator (compensator).

It is made by measuring the voltage between the ends of the shaft, as well as between the foundation plate and the insulated bearing housing. In this case, the tension between the foundation plate and the bearing should be no more than the tension between the ends of the shaft. A difference between voltages of more than 10% indicates an insulation failure.

14. Testing the generator (compensator) under load.

The load is determined by practical capabilities during the acceptance tests. The heating of the stator at a given load must correspond to the specifications.

15. Determination of the characteristics of the collector exciter.

The no-load characteristic is determined up to the highest (ceiling) voltage value or the value set by the manufacturer.

The load characteristic is taken when the load on the generator rotor is not lower than the rated excitation current of the generator. Deviations of characteristics from the factory ones must be within the permissible measurement error.

16. Testing the terminal leads of the stator winding of the TGV series turbogenerator.

In addition to the tests specified in Tables 1.8.1 and 1.8.3, end terminals with capacitor glass epoxy insulation are subjected to tests according to clauses 16.1 and 16.2.

16.1. Measurement of the dielectric loss tangent (tg δ).

The measurement is carried out before installing the end terminal on the turbogenerator at a test voltage of 10 kV and an ambient temperature of 10-30ºС.

The tg δ value of the assembled terminal should not exceed 130% of the value obtained from factory measurements. In the case of measuring tg δ of the end terminal without porcelain covers, its value should not exceed 3%.

16.2. Checking gas tightness.

The gas tightness test of the end terminals, tested at the factory with a pressure of 0,6 MPa, is carried out with a compressed air pressure of 0,5 MPa.

The end terminal is considered to have passed the test if, at a pressure of 0,3 MPa, the pressure drop does not exceed 1 kPa/h.

17. Measurement of the residual voltage of the generator when the AGP is turned off in the rotor circuit.

The value of residual stress is not standardized.

18. Testing the generator (compensator) under load.

The load is determined by practical capabilities during the acceptance tests. Stator heating at a given load must correspond to the manufacturer's data.

Table 1.8.1. Acceptable values ​​of insulation resistance and adsorption coefficient

Table 1.8.2. Test rectified voltage for stator windings of synchronous generators and compensators

Table 1.8.3. Power frequency test voltage for windings of synchronous generators and compensators

* For terminals tested at the factory together with the stator winding insulation.

** For reserve terminals before installation on the turbogenerator.

Table 1.8.4. Permissible deviation of DC resistance

Table 1.8.5. Insulation resistance and test voltages of excitation system elements

Table 1.8.6. Limit values ​​of vibration of generators and their exciters

* if vibration velocity monitoring equipment is available, it is measured; the root-mean-square value of vibration velocity should not exceed 2,8 mm s-1 along the vertical and transverse axes and 4,5 mm s-1 along the longitudinal axis.

See other articles Section Rules for the installation of electrical installations (PUE).

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