How to Calibrate a Velocity Sensor with the AT-2040
The AT-2040 Portable Vibration Calibrator can be used to test and verify velocity sensors by applying a known vibration level and comparing the sensor output to the internal reference measurement.
Typical velocity sensor checks
- Velocity sensitivity in mV/IPS or mV/mm/s
- Reference vibration level
- Sensor output response
- Frequency response verification
- Manual or automatic test workflow
- PDF and CSV report export
What the AT-2040 does during a velocity sensor calibration
A velocity sensor produces an electrical signal proportional to vibration velocity. Depending on the sensor, the output may be specified in mV/IPS, mV/mm/s, or V/IPS.
During calibration, the AT-2040 drives its internal electrodynamic shaker at a controlled vibration level and compares the sensor output to the internal reference measurement. This allows the operator to verify sensitivity, frequency response, and general sensor performance.
AT-2040 velocity support
Velocity sensors can be piezoelectric or moving-coil
Before testing, confirm the type of velocity sensor, the connector pinout, and whether the sensor requires power or produces a passive output.
Piezo velocity sensor
A piezo velocity sensor produces an AC voltage proportional to velocity. These sensors are commonly used in machine protection, low-frequency monitoring, and condition monitoring systems.
- Typical sensitivity: mV/IPS or mV/mm/s
- Often used for industrial vibration monitoring
- May require the correct signal cable or adapter
- Verify wiring and sensor power requirements from the datasheet
Moving-coil velocity pickup
A moving-coil velocity pickup is a seismic sensor that generates a voltage proportional to velocity. These are often used on older protection systems and turbine or rotating equipment monitoring systems.
- Typical sensitivity: mV/IPS or V/IPS
- Common on legacy machine protection systems
- May use multi-pin or special-purpose cables
- Mounting orientation and cable connection are important
Prepare the sensor, cable, and mounting hardware
Velocity sensors are often larger and heavier than accelerometers. Proper mounting, correct cable wiring, and shaker payload limits are important for repeatable results.
Check the sensor datasheet
Confirm the sensor sensitivity, units, connector type, wiring, frequency range, operating orientation, and recommended calibration level.
Select the correct fixture
Use the correct adapter disc, stud, or custom fixture for the sensor. Large velocity sensors may require a dedicated mounting adapter to keep the sensor stable.
Check sensor mass
Confirm that the sensor and fixture are within the shaker limits at the desired frequency and amplitude. Heavier sensors reduce the available vibration output.
Connect the velocity sensor to the AT-2040
Mount the velocity sensor to the shaker reference platform using the correct adapter or fixture. Then connect the sensor output to the AT-2040 using the proper velocity sensor cable or custom interface cable.
For velocity coil sensors, create or select the correct sensor setup and use velocity units such as IPS or MMS. For special sensor wiring, use the sensor datasheet to confirm signal, common, and power connections before starting the test.
Connection checklist
- Sensor mounted securely
- Correct adapter or fixture installed
- Correct velocity sensor cable connected
- Sensor type and units confirmed
- Velocity units selected: IPS or MMS
- Payload and frequency limits checked
Manual velocity sensor test
Manual mode is useful when you want to quickly verify one calibration point, troubleshoot a sensor, check wiring, or compare the sensor output at a specific frequency and velocity level.
Open Vibration Output
From the main menu, select Vibration Output.
Select the sensor input
Select the appropriate velocity or coil sensor setup for the sensor and cable being used.
Select velocity units
Use IPS for inches per second or MMS for millimeters per second.
Set frequency and amplitude
Use the knobs or touchscreen entry fields to set the test frequency and target velocity level.
Start the test
Select Start and allow the vibration level and sensor output to stabilize.
Read sensitivity
Review the live vibration and measured sensor sensitivity, such as mV/IPS or mV/mm/s.
What to watch during the test
During a velocity sensor test, the operator should monitor both the mechanical vibration level and the sensor response. Mounting and payload effects can be more noticeable with larger velocity pickups.
Live vibration
Shows the actual shaker vibration output in velocity units such as IPS or MMS.
Sensitivity
Displays calculated sensor sensitivity, typically in mV/IPS, mV/mm/s, or V/IPS.
Output level
Helps identify whether the shaker is approaching its output capability for the selected frequency and payload.
THD / displacement
Helps identify high distortion, excessive displacement, or low-frequency operating limits.
Velocity calibration is frequency dependent
Velocity, acceleration, and displacement are mathematically related. At low frequency, a velocity level may require a large displacement. At higher frequency, the same velocity level may require more acceleration.
Because of this, always confirm that the requested velocity point is within the AT-2040 shaker capability for the sensor mass, fixture mass, frequency, and selected amplitude.
Useful relationship
For sinusoidal vibration, velocity can be converted to acceleration using frequency. This is useful when checking whether a requested velocity level is within the shaker’s acceleration limits.
Acceleration = 2π × Frequency × Velocity
Higher frequency increases acceleration.
Lower frequency increases displacement.Run an automatic velocity sensor test
For a full calibration or frequency response check, use the AT-2040 Sensor Test mode. The automatic test runs through stored test points, displays results in graph or table view, and saves the data to onboard memory.
Automatic test records
The automatic test screen can show test status, reference reading, current step, deviation relative to the reference frequency, serial number, graph/table view, and Start/Stop control.
When the test is complete, the results are saved onboard and can be exported later from the Reports screen.
Typical velocity sensor calibration setup
Exact test points should be based on the sensor datasheet, customer requirements, and your laboratory procedure. A common approach is to verify sensitivity at a reference frequency and then sweep additional frequency points.
| Setup item | Typical choice | Why it matters |
|---|---|---|
| Sensor type | Piezo velocity or moving-coil velocity pickup | Determines the correct input path, cable, and sensitivity units. |
| Units | IPS or MMS | Velocity sensors are calibrated in velocity units. |
| Reference frequency | Often 100 Hz or customer-defined | Used as the main sensitivity reference point. |
| Amplitude | Known velocity level within shaker limits | Used to calculate and verify velocity sensitivity. |
| Sensitivity units | mV/IPS, mV/mm/s, or V/IPS | Must match the sensor datasheet or customer specification. |
| Output format | PDF certificate and CSV data | Supports customer records, quality systems, and further analysis. |
Velocity sensors are not calibrated the same way as accelerometers
The physical shaker motion is the same, but the sensor output is scaled to velocity rather than acceleration. The test setup should match the sensor’s specified measurement units.
| Feature | Velocity sensor | Accelerometer |
|---|---|---|
| Measured quantity | Velocity | Acceleration |
| Common units | IPS or MMS | g or m/s² |
| Typical sensitivity | mV/IPS, mV/mm/s, or V/IPS | mV/g, pC/g, or mV/m/s² |
| Common application | Machine protection and low-frequency monitoring | General vibration measurement and condition monitoring |
| Important limit | Low-frequency velocity may require large displacement | High-frequency acceleration may be limited by payload and force |
Export calibration results
After the velocity sensor test is complete, the AT-2040 stores the result in onboard memory. Reports can be recalled and exported as PDF or CSV files for documentation, review, or customer delivery.
Report outputs
- PDF calibration certificate
- CSV measured data
- Sensor serial number
- Frequency points
- Velocity amplitude levels
- Sensitivity and deviation data
Pass/fail decisions are controlled by your lab procedure
The AT-2040 provides the measured velocity sensitivity data, deviation, phase information, and calibration records. It does not force a universal pass/fail decision because laboratories may use different tolerances, uncertainty budgets, and decision rules.
When issuing a statement of conformity, apply your own ISO 17025 decision rule or the decision rule requested by your customer.
Common velocity sensor calibration problems
No sensor response
Confirm the cable wiring, input selection, sensor type, and connector pinout. Some velocity sensors require special cables or signal conditioning.
Unstable sensitivity
Check that the sensor is mounted securely, the fixture is tight, and the cable is not pulling on the sensor during the test.
Amplitude limit warning
Reduce the velocity level, check the sensor and fixture mass, or select a different frequency point. Velocity testing can be limited by displacement at low frequency or acceleration at higher frequency.
Agate Technology can help you set up the right AT-2040 workflow.
Whether you are verifying a single velocity sensor or building a repeatable calibration process, the AT-2040 can support manual testing, automatic sweeps, PDF certificates, and CSV export.
