Self-check: Is the instrument power supply abnormal?

First, always compare speed test results with the factory report.
Therefore, the motion sensor must be the same type and mounted in the same position as the one used by the circuit-breaker manufacturer. Sensors designed for different kinds of motion must never be swapped at will.

✔ Linear-motion sensors (linear potentiometers, accelerometers, digital linear, laser, etc.) measure the straight-line travel of the pull-rod or similar parts.
✔ Rotary-motion sensors (rotary potentiometers, digital encoders, gyroscopes, etc.) measure the angular rotation of the crank-shaft or similar parts.

Speed = 0?
On the test screen there is a “Speed Trigger” item (default A1).
Whenever you change the phase under test, change the Speed Trigger to the same contact (e.g., if the contact leads are on B1, set Speed Trigger to B1).
Leaving it on A1 while reading B1 will give a B1 time and a stroke curve, but the calculated speed will be zero.

Settings: stroke length and speed definition must exactly match the manufacturer’s values.

Sensor type must be selected as specified.
Example: if an XC355 analogue rotary sensor is used, choose “Analogue Linear” in the menu; selecting “Gyroscope” will produce an incorrect curve.

Speed definition must follow the manufacturer’s rule.
Most definitions are tied to the instant of contact-make or -break, so the breaker-contact test leads must be connected and the recording time must be long enough to capture the full open/close travel curve.