Lift variation, stability and general technical requirements

Update time : 2024-12-04 16:41:24

3.2 Rise and fall variation

【JJG313-2010】The difference in the error measurement results of the same current percentage point during the current rise and fall of the current transformer is called the rise and fall variation.

For the current transformer with an accuracy level of 0.2 or above used as a standard, the rise and fall variation shall not be greater than 1/5 of its error limit.

【JJG314-2010】The difference in the error measurement results of the same voltage percentage point during the voltage rise and fall of the voltage transformer is called the rise and fall variation.

For the voltage transformer with an accuracy level of 0.2 or above used as a standard, the rise and fall variation shall not be greater than 1/5 of its error limit.

3.3 Stability

【JJG313-2010】The error change of the current transformer shall not be greater than 1/3 of its error limit during the calibration cycle.

【JJG314-2010】The error change of the voltage transformer shall not be greater than 1/3 of its error limit during the calibration cycle.

【Article Interpretation】As a measuring instrument, the value must be stable. If the deviation occurs between two calibrations, it will cause a value error.

If the standard instrument being tested is used for value transfer, it will cause value confusion.

Therefore, the measuring instrument must show a sufficiently good value stability at least in the interval between two calibrations.

Generally speaking, the value stability of electromagnetic transformers is relatively good, but if an error compensation circuit is added to the secondary side of the transformer, or an iron core material with unstable magnetic properties is used, it will affect the value stability of the transformer.

When determining the value stability index of the measuring transformer, the actual situation in my country should also be considered.

When revising the JJG313-1994 and JJG314-1994 regulations, the value stability requirements of the measuring transformer were specifically proposed, which should at least reach the level of general instruments, that is, one-third of the error limit.

4 General technical requirements

4.1 Appearance

【JJG313-2010】The appearance of the current transformer should be intact, the terminal markings should be clear and complete, and the insulation surface should be dry and free of discharge marks.

【JJG314-2010】The appearance of the voltage transformer should be intact, and the terminal markings should be clear and complete.

The oil level of the oil-insulated transformer is correct, the gas-insulated transformer has normal filling pressure, the high-voltage bushing has no insulation defects, and there are no discharge marks on the high and low voltage insulation surfaces.

4.2 Insulation

【JJG313-2010】

4.2.1 The insulation resistance of the current transformer shall comply with the requirements of JB/T5472 Section 6.7

4.2.2 The power frequency insulation withstand voltage of the current transformer shall comply with the requirements of JB/T5472 Section 6.8.1.

【JJG314-2010】

4.2.1 The insulation resistance shall comply with the requirements of JB/T5473 Section 6.6.

4.2.2 The power frequency insulation withstand voltage shall comply with the requirements of JB/T5473 Section 6.7.1

4.2.3 The power frequency induction withstand voltage shall comply with the requirements of JB/T 5473 Section 6.7.2

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