GB 20840.3-2013Instrument transformers -- Part 3: Additional requirements for inductive voltage transformers (English PDF)

3.1 General definitions

3.1.301

Voltage transformer A normal conditions of use and its secondary voltage is proportional to the actual primary voltage, and when the phase difference is close to the correct coupling method Zero transformers.

[GB/T 2900.15-1997, the definition 3.4.30] 3.1.301.1 Electromagnetic voltage transformer inductivevoltagetransformer One kind of electromagnetic induction by the primary voltage converted into a proportional voltage transformer secondary voltage. This transformer is not attached other changes Primary voltage electrical components (e.g., capacitors).

3.1.302

Ungrounded voltage transformer unearthedvoltagetransformer Comprising a primary winding terminals, including its various parts are rated insulation level ground insulation voltage transformer.

[GB/T 2900.15-1997, the definition 3.4.31] 3.1.303 Ground voltage transformer earthedvoltagetransformer One end of the primary winding directly earthed single-phase voltage transformer, the primary winding or star connection point is directly earthed three-phase voltage mutual Sensors.

[GB/T 2900.15-1997, the definition 3.4.32] 3.1.304 Measuring voltage transformer the measuring instruments, meters and similar appliances integral transmission of the information signal voltage transformer.

[Rewrite GB/T 2900.15-1997, the definition 3.4.33] 3.1.305 Protective voltage transformer the protection and control means for transmitting the information signal voltage transformer.

[GB/T 2900.15-1997, the definition 3.4.34] 3.1.306 the primary winding is converted voltage applied to the windings.

[GB/T 2900.15-1997, the definition 4.3.6] 3.1.307 Secondary winding Voltage power supply circuit to the winding measuring instruments, instrument integration, protection or control devices.

[GB/T 2900.15-1997, the definition 4.3.9] 3.1.308 Residual voltage winding A single-phase voltage transformer winding for coupling to an opening in a three-phase delta group of three single-phase voltage transformer, which mesh it is.

a) generating a residual voltage when a ground fault;

b) the relaxation oscillation damping (ferromagnetic resonance).

[GB/T 2900.15-1997, the definition 4.3.20]

3.2 For definitions of the electrical insulation rating 3.2.301 Rated primary voltage Upr as voltage transformer primary voltage performance benchmarks.

[GB/T 2900.15-1997, the definition 2.3.29] 3.2.302 Rated secondary voltage Usr Voltage transformer secondary voltage value as performance benchmarks.

[GB/T 2900.15-1997, the definition 2.3.31] 3.2.303 Rated voltage factor Fv Factor with a rated primary voltage multiplied to determine the thermal voltage transformer should meet the relevant performance requirements within the specified time and meet the highest voltage level about the exact requirements.

[GB/T 2900.15-1997, the definition 2.3.26]

3.4 Concerning the definition of accuracy

3.4.3

The ratio difference ratioerror 3.4.3 with the following additions to the content of GB 20840.1-2010 are applicable.

The ratio difference (voltage error) the percentage represented by the following formula.

epsilon =

kr × Us-Up

× 100

Where.

epsilon --- ratio difference (voltage error),%;

kr --- rated transformation ratio;

Up --- the actual primary voltage, in volts (V);

Us --- In the measurement conditions, the actual secondary voltage Up is applied when the unit is volt (V).

3.5 Other definitions of ratings

3.5.301

Thermal limit output thermallimitingoutput at rated voltage, secondary winding can supply and temperature does not exceed the prescribed limits of the apparent power value.

301 Note. In this state, all ratios and phase difference between the secondary winding almost exceeds the limit.

302 Note. There are a plurality of secondary windings, the thermal limit output value of the windings should be separately marked.

303 Note. In addition to producing otherwise agreed with the user, not allowed to have two or more secondary windings while supplying thermal limit output.

3.7 Symbol and Name

GB 20840.1-2010 3.7 with the following alternatives.

IT transformer

CT current transformer CVT capacitor voltage transformer VT Voltage transformer AIS Air Insulated Switchgear station GIS gas-insulated metal-enclosed switchgear the actual ratio k kr rated transformation ratio epsilon ratio difference the phase difference deltaphi Sr Rated output Usys maximum system voltage Highest voltage for equipment Um Rated primary voltage Upr Rated secondary voltage Usr Fv Rated voltage factor Rated frequency fr F mechanical loads Frel relative leak rate

5.2 Highest voltage for equipment

5.2 and the content of the following supplemental GB 20840.1-2010 are applicable.

The nominal voltage of the system voltage equipment highest standard value 1000kV voltage transformer in accordance with the provisions of GB 311.1.

5.3 Rated insulation level

5.3.2 a side rated insulation level 5.3.2 with the following additions to the content of GB 20840.1-2010 are applicable.

1000kV system nominal voltage of the voltage transformer primary side rated insulation level shall comply with the provisions of GB 311.1.

5.3.3.2 Truncated lightning impulse

5.3.3.2 with the following additions to the content of GB 20840.1-2010 are applicable.

Nominal system voltage of a voltage transformer terminal 1000kV truncated lightning impulse withstand voltage should be consistent with the GB 311.1 Provisions.

5.3.3.301 Ground terminal of power frequency withstand voltage

Rated frequency withstand voltage should be 3kV (rms).

If the voltage transformer of highest voltage for equipment Um>=40.5kV, the rated frequency withstand voltage should be 5kV (rms).

5.5 Rated output

5.5.301 Rated output value

VA to represent a power factor of 1.0 nominal output standard.

1.0VA, 1.5VA, 2.5VA, 3.0VA, 5.0VA, 7.5VA, 10VA (load series I).

VA to represent a power factor of 0.8 (lagging) nominal output standard.

10VA, 15VA, 20VA, 25VA, 30VA, 40VA, 50VA, 75VA, 100VA (load series II).

There numerical subscript horizontal line under the priority value.

Three-phase voltage transformer rated output should refer to the rated output per phase.

301 Note. For a given transformer, as long as one of its rated output is standard value and meet a standard of accuracy class, rated output is allowed to rest it can be defined as non-standard values, but to meet the requirements of another standard accuracy class.

5.5.302 Nominal heat output limit

Nominal heat output limits should be represented VA. At rated secondary voltage and a power factor of 1.0, the standard value should be.

25VA, 50VA, 100VA and their decimal multiples.

5.5.303 Residual voltage winding rated output

And it intends to open delta winding connection similar to produce a residual voltage winding its rated output shall be expressed in VA and 5.5.301 the predetermined value selected.

Rated thermal limit output 5.5.304 residual voltage winding Rated thermal limit output residual voltage winding shall be expressed in VA. At rated secondary voltage and a power factor of 1.0, the standard Value should 25VA, 50VA, 100VA and their decimal multiples.

301 Note. If the opening couplet form triangular residual voltage windings designated thermal limit output, you should pay attention to these windings it is only in case of failure and where it Bearing a load within the limited time. 3.5.301 different definition, nominal heat output limit of the residual voltage winding is the basis of the duration 8h (In this case, the rated voltage by a factor of 1.9).

Rated accuracy class 5.6

5.6.301 Measurement accuracy requirements of single-phase voltage transformer

5.6.301.1 Measuring voltage transformer accuracy class nominal

Measuring voltage transformer accuracy class, based on the maximum permissible error for the accuracy class voltage at rated voltage and rated load specified A percentage of the nominal.

Standard accuracy class 5.6.301.2 measuring voltage transformers Measuring accuracy class standard single-phase voltage transformer is.

0.1,0.2,0.5,1.0,3.0.

301 Note. it will give information about the appropriate level of accuracy in guiding the future of the appendix.

5.6.301.3 Measuring voltage transformer voltage and phase error limits

In either a voltage 80% to 120% of rated voltage, the voltage error and phase rated frequency shall not exceed 301 table Set value, and the load as follows.

a) for the load power factor I 1 of the series, to any value to 100% of rated load 0VA between.

b) for any value of the power factor of 25% to 100% of rated load of between 0.8 (lag) of the load series II, as.

Error voltage transformer terminals should be measured, and should include a voltage transformer fuse whole or part of the resistor influences.

For the secondary winding voltage transformer with a tap, if not otherwise specified, then the exact level of the requirements refers to the maximum ratio.

Table 301 measuring voltage transformer voltage and phase error limits

Accuracy class

Voltage error (ratio error) ±% Retardation ± ( ') ± crad 0.1 0.2 0.5 1.0 3.0 0.1 0.2 0.5 1.0 3.0 not specified 0.15 0.3 0.6 1.2 not specified

301 Note. For two independent voltage transformer secondary winding should consider the interaction between the two secondary windings. Necessary to provide each winding test Output range, and in the non-tested winding with any value from 0 to the rated load, each of the tested winding should be within the specified output range Meet the requirements of accuracy class.

If not specified output range, the output range of each winding test should meet the 5.6.301.3a) or 5.6.301.3b) provisions.

If a winding only occasional short-term load, or use only as a residual voltage winding, then the impact on the rest of the windings is negligible.

5.6.302 Protection with additional technical requirements for single-phase voltage transformer

5.6.302.1 Protective voltage transformer accuracy class nominal

All for protective voltage transformer, in addition to residual voltage winding, shall be in accordance with the provisions of its 5.6.301.1 and 5.6.301.2 measurement accuracy level. Furthermore, it should have an accurate level of 5.6.302.2.

Protective voltage transformer accuracy class, based on the exact level of 5% from the rated voltage to the rated voltage factor (see 5.302) corresponding to the electrical the maximum allowable percentage of nominal voltage error within the pressure range. Followed by the letter P.

5.6.302.2 Standard accuracy classes for protection of voltage transformer

Protection standard voltage transformer accuracy class of 3P and 6P, 5% of the rated voltage and rated voltage factor corresponding to the voltage, both Voltage and phase error limits are usually the same. 2% at the rated voltage of twice the error limits of the limits of error of 5% of the rated voltage.

5.6.302.3 Protective voltage transformer voltage and phase error limits

At 5% of the rated voltage and rated voltage multiplied by the rated voltage factor (1.2, 1.5 or 1.9) of the voltage, the voltage at its rated frequency error and the phase difference should not exceed the values listed in Table 3...