How to Calibrate a Charge Mode Accelerometer with the AT-2040
The AT-2040 Portable Vibration Calibrator can be used to manually verify or automatically calibrate charge output accelerometers by comparing the sensor under test to the built-in reference accelerometer.
Typical charge sensor checks
- Charge sensitivity in pC/g
- Reference vibration level
- Sensor output response
- Cable and mounting verification
- Frequency response sweep
- PDF and CSV report export
What the AT-2040 does during a charge accelerometer calibration
A charge mode accelerometer produces a charge output instead of a powered IEPE voltage output. During calibration, the AT-2040 drives its internal electrodynamic shaker at a controlled vibration level and compares the charge sensor output to the internal reference accelerometer.
The AT-2040 includes the required charge input signal path, allowing the operator to measure charge accelerometer sensitivity directly, typically in pC/g. This makes the AT-2040 useful for testing high-temperature accelerometers, charge-mode industrial sensors, and sensors used with external charge amplifiers.
AT-2040 charge input support
Prepare the charge accelerometer, cable, and mounting hardware
Charge mode sensors are sensitive to mounting and cable handling. For best results, use the correct adapter, secure the sensor properly, and avoid cable movement during the test.
Check the sensor datasheet
Confirm the sensor sensitivity, connector type, mounting thread, operating frequency range, and recommended calibration amplitude before beginning the test.
Use the correct low-noise cable
Charge sensors should be connected with the proper low-noise cable or adapter. Cable movement can affect charge measurements, so route and secure the cable before running the test.
Use the short-handle wrench
Hold the reference accelerometer with the provided short-handle wrench while installing or removing the test sensor. This prevents twisting force from being applied to the shaker.
Connect the charge accelerometer to the AT-2040
Mount the charge accelerometer to the shaker reference platform using the correct stud or adapter. Then connect the sensor to the AT-2040 sensor input using the correct charge-mode cable or adapter.
Unlike IEPE sensors, charge mode accelerometers do not require an IEPE constant-current supply. The AT-2040 uses its charge input signal path to measure the sensor output and calculate charge sensitivity.
Connection checklist
- Sensor mounted securely
- Correct stud or adapter installed
- Charge cable connected to sensor input
- Cable secured to reduce movement
- Charge channel selected
Manual charge sensor test
Manual mode is useful when you want to quickly verify one calibration point, troubleshoot a sensor, check a cable, or compare the sensor output at a specific frequency and amplitude.
Open Vibration Output
From the main menu, select Vibration Output.
Select Charge
Tap the Channel button and select Charge.
Use acceleration units
For charge accelerometer input, use GS as the vibration unit.
Set frequency and amplitude
Use the knobs or touchscreen entry fields to set the test frequency and target vibration level.
Start the test
Select Start and allow the vibration level to stabilize.
Read sensitivity
Review the live vibration and measured sensor sensitivity, typically shown as pC/g.
What to watch during the test
During a charge sensor test, the AT-2040 gives the operator useful indicators that help confirm the sensor, mounting, cable, and vibration level are behaving correctly.
Live vibration
Shows the actual shaker vibration output in the selected acceleration units.
Sensitivity
Displays calculated sensor sensitivity, typically in pC/g for charge accelerometers.
Output level
Helps identify whether the shaker is approaching its output capability at the selected frequency and payload.
THD / displacement
Helps identify high distortion, excessive displacement, or operating conditions outside the best test range.
Run an automatic charge accelerometer 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 charge accelerometer calibration setup
Exact test points should be based on the sensor datasheet, customer requirements, and your laboratory procedure. A common approach is to verify charge sensitivity at a reference frequency and then sweep additional frequency points.
| Setup item | Typical choice | Why it matters |
|---|---|---|
| Sensor type | Charge accelerometer | Selects the correct charge input path and sensitivity units. |
| Reference frequency | Often 100 Hz or customer-defined | Used as the main sensitivity reference point. |
| Amplitude | Commonly 1 g, unless otherwise specified | Keeps testing repeatable and comparable to prior records. |
| Units | GS | Charge accelerometer input measures acceleration. |
| Output format | PDF certificate and CSV data | Supports customer records, quality systems, and further analysis. |
Charge mode sensors are different from IEPE sensors
Both sensor types are accelerometers, but they use different electrical interfaces. Selecting the correct channel is required for the AT-2040 to read the sensor correctly.
| Feature | Charge accelerometer | IEPE accelerometer |
|---|---|---|
| Output type | Charge output | Voltage output with DC bias |
| Typical sensitivity | pC/g | mV/g |
| AT-2040 channel | Charge | IEPE |
| Sensor power | No IEPE current source required | Requires IEPE current source |
| Cable sensitivity | Use proper low-noise cable and avoid cable motion | Less sensitive to cable motion than charge mode |
Export calibration results
After the charge accelerometer 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
- Charge sensitivity results
- Deviation and phase data when applicable
Pass/fail decisions are controlled by your lab procedure
The AT-2040 provides the measured charge 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 charge accelerometer calibration problems
No sensor response
Confirm the Charge channel is selected, the sensor cable is connected, and the cable or adapter is correct for charge mode measurement.
Unstable sensitivity
Check sensor mounting, adapter tightness, cable routing, and cable movement. Charge measurements are more sensitive to cable handling than IEPE measurements.
Amplitude limit warning
Reduce the vibration level, check the payload weight, or use a different frequency point. Shaker output limits depend on frequency and sensor mass.
Agate Technology can help you set up the right AT-2040 workflow.
Whether you are verifying one charge accelerometer at a time or building an automated calibration process, the AT-2040 can support manual testing, automatic sweeps, PDF certificates, and CSV export.
