How to divide the accuracy level of the transformer

The accuracy level of the current transformer is to say that its measurement error (accuracy) is generally ,,,5p, 10p, etc. The special current transformer with s requires high enough accuracy in the load range of 1 120, and the error is less than the specified range when measured by 5 load points; , etc. is generally the measurement coil, the accuracy of the error 20 120 load range is required to be high enough, and the error is generally less than the specified range (the error includes the ratio difference and the angle difference, because the current is a vector, so the size and phase angle difference are required), and the current transformer of 5p, 10p is generally used for relay protection, that is, the compound error is required to be less than a certain value under the short-circuit current, 5p is less than 5, 10p is less than 10; Therefore, the current transformer stipulates different accuracy according to the application, that is, the error accuracy in different current ranges.

The accuracy of the current transformer is to say that its measurement error (accuracy) is generally 5p, 10p, etc.

The principle of determining the accuracy level of the current transformer is as follows: the error test of the current transformer is generally compared with the standard transformer under test, and the secondary current difference between the two transformers is the error of the tested transformer. This test method is called the comparative method.

The standard transformer is required to be two levels higher than the transformer under test, and the error of the standard transformer is negligible. If the standard transformer is only one level higher than the transformer under test, the error of the test result should be considered plus the error of the standard transformer.

The secondary current difference between the tested transformer and the standard transformer is generally measured by the transformer calibrator. Read out the ratio difference fx(%) phase difference δx(') directly from the transformer calibrator Because the transformer calibrator measures the ratio of the current difference between the transformer and the standard transformer to the secondary current, the requirements for the transformer calibrator are not high. What level of transformer can be verified is basically determined by the standard transformer.

The standard instrument transformer is the key core of the instrument transformer calibration system. To calibrate the tested transformer, in addition to the standard transformer and transformer calibrator, there should also be a current riser that provides primary current to the transformer, a voltage regulator that can adjust the current of the current booster, and a load.

Current transformers.

Grade is the standard grade of current transformer.

It refers to a level of transformer manufactured to meet the requirements of special use. Compared with ordinary level transformers, the test range to ensure accuracy is wider. Some literature believes that the test range of the level transformer is 1% to 100%, which is not rigorous.

From the point of view of the verification regulations, the level transformer is rated at 20%.

or voltage), the accuracy has dropped to the point, while the level can still be guaranteed.

For more detailed index differences, please refer to the "JJG 313-2010 Verification Regulations for Measurement Current Transformers" and "JJG 314-2010 Verification Regulations for Measurement Current Transformers".

The details are as follows:

The accuracy level of the current transformer is as follows0, D grade. The current transformers used in measurement and metering instruments are graded, graded, and only used as a current transformer for current and voltage measurement are allowed to be used in the stage, and the stage is allowed to be used for non-important measurements.

1. Accuracy of current transformer for calibration: level. Error, which is often used to verify the accuracy of metering-grade current transformers.

2. Accuracy of current transformer for metering: level. Error sum is used as the basis for the settlement of electricity bills, and grades will also be used in some occasions.

3. Measurement-grade current transformer: stage, stage, stage, etc., generally used for ammeter.

Refers to the accuracy Generally speaking, the measurement selection is the measurement selection, that is, the measured value within the rated current range does not exceed the positive or negative of the accurate value.

Like, grade can be equipped with a meter, grade and higher to special S grade is generally used in the laboratory, like grade 1, grade 3 and lower are generally not suitable for measurement. There are also two grade joints like a high-voltage Ponson transformer, which are generally marked on the nameplate and instructions. In accordance with the provisions of "JJG313-2010 Verification Regulations for Current Transformer for Measuring Yuhe" and "JJG314-2010 Verification Regulations for Voltage Transformer for Measurement".

The maximum ratio difference (proportional error, also known as assignment error) of the voltage transformer and the current transformer is less than 10 under 50Hz, rated voltage or rated current. The S-class transformer is used for metering because the range of error requirements is larger than that without S.

The accuracy level of the current transformer is to say that its measurement error is generally ,,,5p, 10p, etc.

The special current transformer with S requires high accuracy in the load range of one percent to one hundred and two percent, and generally takes 5 negative load points to measure its error less than the specified range;

Generally speaking, it is the measurement coil, which requires an error of 20% to 102% and the accuracy is high enough in the load range, and the error is generally measured by 4 load points, and the error is not less than the specified range;

5P, 10P current transformer is generally used for relay protection, that is, the compound error is required to be less than a certain value under the short-circuit current;

5p is less than 5, 10p is less than 10, so the current transformer has different accuracy according to the use of the standard, that is, the error accuracy in different current ranges.