Ammeter use and maintenance method - Solutions - Huaqiang Electronic Network

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1. Choosing the Right Ammeter

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

(2) Choose an ammeter with a range that matches the expected current. If the range is too large, the accuracy may decrease; if it's too small, the ammeter could be damaged. To maximize accuracy, select a range so that the measured value falls within the last quarter of the scale.

(3) Ensure the ammeter has a low internal resistance to minimize its impact on the circuit being measured. This helps maintain accurate readings without altering the actual current flow.

2. Pre-Measurement Inspection

Before starting any measurement, check that the ammeter pointer is aligned with the "0" mark. If not, adjust the zero adjuster to ensure the pointer is correctly set to zero.

3. Connecting the Ammeter to the Circuit

(1) When measuring, connect the ammeter to the low potential side of the circuit to avoid damaging the meter or affecting the circuit’s performance.

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

4. Correct 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, ensure the pointer and its reflection are perfectly aligned to reduce inaccuracies.

5. Maintenance and Safety Tips

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

(2) If the needle deflects beyond the full-scale mark in either direction, stop the measurement immediately, turn off the power, and recheck the connections or use a higher-range ammeter to prevent damage.

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