Ultra low frequency sensor calibration system

1.System Introduction and Application

When designing or using sensors, the frequency response characteristics and sensitivity of the sensor are quite important technical indicators.WS-5937superThe low-frequency sensor calibration system isSpecially designed for calibrating the frequency response curve and sensitivity of low-frequency speed and acceleration sensors, this system can achieve computer automatic closed-loop control for "sensor frequency response curve calibration", measure the frequency amplitude of the standard sensor and the calibrated sensor, calculate the frequency response and sensitivity of the calibrated sensor, and complete the calibration of the frequency response curve according to user requirements.

This system can be applied to metrology research institutes, vibration research laboratories, sensor research and production units, etc.

By utilizing proprietary technology, this system can also calibrate the sensitivity and frequency response curve of ultra-low frequency velocity sensors (detectors), which are widely used in fields such as petroleum geophysical exploration and mechanical vibration monitoring in factories and mines.

2.System Composition

2.1 WS-5937Calibration controller1Taiwan;

2.2 WS-PA-30DorWS-PA-50DLow frequency power amplifier1Taiwan;

2.3 Low frequency exciterJZ-20D 1Taiwan orJZ-50D 1Taiwan;

2.4 Sensor calibration softwareVib’SIN 1Set;

2.5 Standard sensors1Only;

2.6 computer1Taiwan (self provided);

3.software interface

4.System composition logic diagram

5.function

5.1 Scan frequency points and amplitudes according to user customization;

5.2 The software automatically generates scanning curves, with equal frequency intervals and equal amplitude scans;

5.3 Automatic control of amplitude error;

5.4 Automatically generate frequency response characteristic curve data (volt frequency, phase frequency);

5.5 Frequency response characteristic curve plotting (linear, logarithmic);

5.6 Programmable signal generator, waveform selection: sine wave, single frequency signal output, signal sweep, frequency dwell;

5.7 Online assistance;

6.technical indicators

6.1 WS-5937Calibration controller

6.1.1Data collection and control signals:

1）ComputerUSBInterface control and collection;

2）Data collection frequency60kHz/通道；

3）24bit4Road data collection, input range ±5V；

4）1road16bitD/ADigital to analog conversion signal output channel;

5）Control signal output amplitude ±10V, amplitude resolution16Position, amplitude control accuracy0.1％FS；

6）Control the sweep frequency range0.1Hz~500Hz, frequency resolution28Position, frequency control accuracy0.01Hz；

7）Supply voltage:100V~240V(AC)；

8）Size: Width365X high70X deep365mm；

6.1.2Charge amplifier:

1) OLEDDisplay parameters;

2)One encoder key sets all charge amplifier parameters;

3)Number of channels:2通道；

4)Input range: ±100000pC；

5)Gain:5档；

6)Normalization:0.1~999；

7)Accuracy: Acceleration:≤±0.5％；

speed:≤±0.5％；

displacement:≤±2.0％；

8)Frequency range: Acceleration: 0.3Hz~50kHz；

speed: 1.0Hz~10kHz；

displacement: 1.0Hz~1kHz；

9)Low pass filter: ① Filtering method: Programmable8Order continuous filtering;

② Programmable low-pass filtering frequency:1Hz~50kHz(arbitrarily set)

③ Filter stopband attenuation:-80dB/Oct；

10)Output voltage: ±10V

11)Overload indication: Input voltage exceeds ±9.8VtimeLEDThe indicator light is on;

12)Output noise: ≤5×10-3pC(Maximum gain converted to input terminal)

13)Input impedance:1012Ω

14)Output resistance:<1Ω

15)Output current:15mA

16)Working temperature and humidity:-10~50℃、<85％RH(No coagulation)

6.1.3 IEPEadapter

1 ) OLEDDisplay parameters;

2 )One encoder key to set allIEPEAmplifier parameters;

3 )Number of channels:2通道；

4）Voltage input range: ±5V；

5）Gain:5档；

6）Accuracy: Acceleration:≤±0.5%，

speed:≤±0.5%，

displacement:≤±2；

7）Frequency range: Acceleration: 0.1Hz~50kHz，

speed1Hz~10kHz，

displacement: 1Hz1kHz；

8）Low pass filter: filtering method: programmable8Order continuous filtering,

Programmable low-pass filtering frequency:1Hz50kHz(arbitrarily set),

Filter stopband attenuation:-80dB/Oct；

9）Overload indication: Input voltage exceeds ±9.8VtimeLEDThe indicator light is on;

10）Signal to noise ratio:>50dB；

11）Noise ≤5mVrms；

13）Output resistance: ＜1Oh?

14）Output current:15mA；

15）Working temperature:-10~50℃；

6.2 WS-PA-30Dpower amplifier

1)Output power:30W；

2)Maximum output current:3A；

3)Maximum output voltage: ±10V；

4)Frequency range:DC~5kHz；

5)Output impedance:1Oh?

6)Distortion degree:<2％；

7)noise<5mV；

6.3Low frequency exciter

6.2.1 JZ-20DBasic technical specifications of ultra-low frequency exciter(choice1)

1）Working frequency:0.1~500Hz；

2）Maximum displacement:±10mm；

3）Maximum current:10A；

4）He Carrying:1000g

6.2.2 JZ-50DBasic technical specifications of ultra-low frequency exciter (selection)2）

1）Working frequency:0.1~500Hz；

2）Maximum displacement:±10mm；

3）Maximum current:10A；

4）He Carrying:3000g

6.4Standard accelerometer indicators (optional)

6.3.1Model:BK-8305Optional

Manufacturer: DenmarkB&K；

Compliant with standards:ISO 5347；

Sensitivity:1.25pC/g；

Working frequency:1~5000Hz；

Resonant frequency:35kHz；

Maximum measurement:1000g；

Weight:45g；

Operating Temperature-74℃~250℃；

Application: Used for sensitivity calibration of sensors;

Explanation: Due toBK-8305The price is relatively high, you can choose other brands or domestic acceleration sensors with appropriate prices, and then regularly calibrate them at the measurement and testing unit for sensor calibration.

6.3.2Model:WS107

Manufacturer: Beijing Spectrum Company;

Sensitivity:5.5pC/ms^-2；

Working frequency:0.5~5000Hz；

Resonant frequency:25kHz；

Maximum measurement:3000g；

heavy Quantity:30g；

Operating Temperature-20℃~50℃；

should Used for sensitivity calibration of sensors

6.5Laser displacement sensor indicators (optional)

type number:LK-H050+LK-G5001V

Manufacturer: Keyence;

Reference distance:50mm；

Test scope: ±10mm；

Linearity: ±0.02%F.S；

Repeatability0.025Mm*3；

Ambient temperature0℃~50℃；

Sampling period:2.55/5/10/20/50/100/200/500/1000Ms(optional9Type level)；

should Used for sensitivity calibration of low-frequency sensors (frequency)0-10Hz）

7.Order model

8.Low frequency vibration table JZ-20D and JZ-50D self frequency response curves

Low frequency vibration tableJZ-20DFrequency response curve（1~500Hz）

Low frequency vibration tableJZ-50Dfrequency response curve(0.1~100Hz)

9.Example of frequency response characteristic curve of sensor

9.1 example1：4.5HzFrequency response and phase curve of speed detector

4.5HzFrequency response and phase curve of speed detector1-500Hz

4.5HzFrequency response and phase curve of speed detector1-50Hz

9.2 example2：10HzFrequency response and phase curve of speed detector

10HzFrequency response and phase curve of speed detector1-50Hz

10HzFrequency response and phase curve of speed detector1-500Hz

9.3 example3A low-frequency acceleration sensorEcho curve

The technical parameters of this sensor indicate the frequency response0.2to2500Hz，500mV/gWhen calibrating with low frequency0.1to0.7HzNon linearity (curve from high to low) occurs due to the low sensitivity of the sensor. When measuring low frequencies, the noise of the sensor itself is already greater than the calibration value of the calibration table.

frequency response curve0.1-10Hz

frequency response curve0.1-80Hz

10.Calibration question: Is the system accurate?

Regardless of whether the power amplifier and exciter used in the calibration system are domestic or imported instruments and equipment, the system always has nonlinearity. However, the sensor calibration adopts the comparison method (usually referred to as the "back-to-back method"), and the calibration is based on the standard sensor to calibrate other sensors. This system recommends using Denmark as the referenceB&Kcompany2Only standard sensors,B&K-4374SMainly used for calibrating the frequency response curve of sensors, andB&K-8305Mainly used for calibrating the sensitivity of sensors and the frequency response curve of low-frequency sensors, currently the domestic metrology department mainly adopts DenmarkB&K-8305As a standard sensor, DenmarkB&K-8305The sensor adoptsLaser absolute method calibration meets international standardsISO 16063-11 (previousISO 5347)The requirements.

11.Triple spectrum of acceleration, velocity, and displacement

They can be identified from the triple spectrum of acceleration, velocity, and displacement3A value at a certain frequency（Hz）The corresponding relationship below. From the figure, it can be seen that at low frequencies, the displacement is relatively large; At high frequencies, the displacement is very small.

Unit and color in the figure: orange accelerationAcceleration（m/s2）, Black SpeedVelocity（mm/s）Blue displacementDisplacement（mm）Black frequencyFrequency（Hz）.