Ammeter use and maintenance method - Solutions - Huaqiang Electronic Network

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1. Choosing the Right Ammeter

(1) Select an ammeter based on the required measurement accuracy. Typically, a 0.1–0.2 grade magnetoelectric ammeter is ideal for standard meters and precision measurements. A 0.5–1.5 grade meter is suitable for lab use, while a 1.0–5.0 grade meter is commonly used in industrial settings for monitoring and maintenance tasks.

(2) Choose an ammeter with a range that matches the expected current. If the range is too high, it may reduce the accuracy of the reading. If the range is too low, it could damage the meter. To ensure the best performance, select a meter so that the measured value falls within the last quarter of the scale.

(3) Ensure the internal resistance of the ammeter is as low as possible to minimize any impact on the circuit being measured.

2. Pre-Measurement Inspection

Before starting the measurement, check if the ammeter's pointer is aligned with the "0" mark. If not, adjust the zero adjustment knob to bring the pointer back to zero.

3. Connecting the Ammeter to the Circuit

(1) When measuring, connect the ammeter to the low potential side of the circuit. This helps prevent unnecessary voltage drops or inaccuracies.

(2) For DC measurements, pay attention to the polarity of the ammeter. For a single-range ammeter, the current should flow into the "+" terminal and out through the "-" terminal. For multi-range meters, the terminal marked "*" is the common terminal. If another terminal is marked "+", the current should enter through "+" and exit through "*". If the other terminal is marked "-", the connection is reversed accordingly.

4. Accurate Reading Techniques

When taking a reading, wait until the pointer stabilizes and then read the value. Keep your line of sight perpendicular to the dial to avoid parallax errors. If the dial has a mirror, make sure the pointer and its reflection are aligned to improve accuracy.

5. Maintenance and Safety Tips

(1) Magnetoelectric ammeters have limited overload capacity, so always check the polarity and range before connecting them to a circuit.

(2) If the pointer deflects beyond the full-scale mark during a measurement, stop the test immediately. Turn off the power, verify the connections, and consider using a higher-range ammeter if needed.

(3) After completing the measurement, disconnect the power supply first, then remove the ammeter from the circuit. Store it in a dry, cool, and well-ventilated area. For microampere or milliampere meters, which are highly sensitive, short-circuit the positive and negative terminals with a wire to protect the internal mechanism.