JJG 644-2003Verification Regulation of Vibration Displacement Transducer (English PDF)

5.1 Appearance and Accessories

5.1.1 The transducer casings shall have a nameplate indicating the product name, specifications, manufacturer, exit-factory date, and serial number, and shall also be marked with the mark and its serial number.

dimensions and installation mode.

5.3 Environmental Adaptability of Transducers

5.3.1 Normal operating environment of transducers.

Temperature. within the temperature range specified by the manufacturer.

Humidity. <=85%RH.

No strong magnetic fields, corrosive gases or liquids, or strong vibration sources in the vicinity.

5.3.2 Test requirements for environmental adaptability

The environmental tests shall comply with the requirements for humidity test and drop test in

Article 3 of JB/T 9329-1999 Basic Environmental Conditions and Testing Methods for

Instruments Transportation and Storage in the Transportation.

Humidity test. 95%RH (25 °C);

Drop test. free fall from a height of 100 mm.

6.1 Type Approval or Prototype Testing

6.1.1 Type approval or prototype testing shall be conducted in accordance with the relevant requirements of JJF 1015-2002 General Norm for Pattern Evaluation and Pattern Approval of

Measuring Instruments and JJF 1016-2002 The Rules for Drafting Program of Pattern

Evaluation of Measuring Instruments.

6.1.2 The items for type approval and prototype testing are shown in Table 2.

6.1.3 The methods for type approval and prototype testing are shown in Appendix A.

6.2 Initial Verification, Subsequent Verification, and In-Use Inspection

6.2.1 Verification conditions

6.2.1.1 Environmental conditions

1) Temperature. (20 ± 5) °C.

2) Humidity. <=85%RH.

3) Power supply voltage fluctuation shall not exceed ±10% of the rated value.

4) The verification site shall be free from the interferences of strong vibration sources and strong magnetic fields, as well as corrosive gases and liquids.

6.2.1.2 Verification instruments and equipment

The following verification instruments and equipment can be selected in accordance with the type and model of the transducer under verification.

1) Instruments and equipment for static calibration.

Displacement (length) measuring instruments.

Third-class standard gauge blocks. measurement uncertainty (0.1 + 1L) µm (k = 3);

Fourth-class standard gauge blocks. measurement uncertainty (0.2 + 2L) µm (k = 3);

Dial indicator. (0 ~ 5) mm, indication error. ±5 µm;

Dial gauge. (0 ~ 10) mm, indication error. ±20 µm;

(0 ~ 25) mm, indication error. ±30 µm;

Displacement static calibrator. (0 ~ 10) mm or (0 ~ 30) mm;

DC digital voltmeter. measurement uncertainty 0.1% (k = 2);

Oscilloscope. indication error ±5%;

DC regulated power supply. voltage stability ±0.1%, ripple voltage < 1 mV.

2) Instruments and equipment for dynamic calibration.

Standard vibration table. acceleration waveform distortion <= 5%; lateral vibration ratio <= 10%;

Acceleration amplitude stability <= 0.5%; signal-to-noise ratio >= 60 dB;

Table surface magnetic leakage <= 3 mT.

Standard accelerometer set.

Reference sensitivity calibration uncertainty.

At 160 Hz or 80 Hz, 0.5% (k = 3);

Within the (20 ~ 1,000) Hz frequency range, 1.0% (k = 3);

AC digital voltmeter. measurement uncertainty 0.2% (k = 2);

Digital frequency meter. measurement uncertainty 0.05% (k = 2).

values measured at the same measurement point in the same stroke during the three cycles shall be obtained, and then the amplitude repeatability shall be calculated in accordance with

Formula (7).

Where,

Deltari---the deltar value at the ith measurement point;

deltari---the amplitude repeatability at the ith measurement point;

UN---the output value of the transducer at full scale.

Its amplitude repeatability shall meet the technical requirements in Item 4 of Table 1 of this

Regulation.

6.2.2.6 Zero error

Install the transducer on the displacement static calibrator. In operating condition, place the displacement transducer at zero point (initial operating point). Use an oscilloscope to measure the transducer’s noise signal. The ratio of this noise signal to the transducer’s output signal at full scale is the transducer’s zero error. Its verification result shall meet the technical requirements in Item 5 of Table 1 of this Regulation.

6.2.2.7 Verification of dynamic reference sensitivity

For transducers fixed with a bracket during measurement, during verification, a suitable bracket shall be used to fix the transducer under verification at a suitable position in the vertical direction of the standard vibration table surface, ensuring that there is no relative movement between the bracket and the non-moving parts of the transducer and the vibration table body.

For transducers that are not fixed with a bracket during measurement and can be directly mounted on the vibrating body under test, during verification, the transducer under verification shall be rigidly mounted on the standard vibration table surface.

Use a standard accelerometer to monitor the vibration table. Within the dynamic range of the transducer under verification, select a certain practical frequency value [recommended (20, 40,

80, 160) Hz] and a specified displacement value [recommended (0.1, 0.2, 0.5, 1.0, 2.0, 5.0) mm] for verification. The ratio of the output value of the transducer under verification to the displacement value of the vibration table is the dynamic reference sensitivity of the transducer.

The dynamic reference sensitivity is calculated in accordance with Formula (8).

Where,

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