Shielding protects an analog meter from?

Shielding protects an analog meter from?

• A. Stray magnetic fields
• B. Electrical noise
• C. Vibration
• D. Temperature drift

Answer: (A)

Shielding around an analog meter is meant to block stray magnetic fields from influencing its measurement. An analog meter often relies on a moving coil in a magnetic field; external magnetic fields from nearby equipment or power lines can couple into that field and exert an extra torque on the coil, causing the needle to deflect or drift inaccurately. A shield made of high-permeability material provides a path for magnetic flux, keeping most of the external field out of the meter’s interior so the indication reflects only the actual signal. Temperature drift, vibration, and some forms of electrical noise involve other causes of error and aren’t primarily mitigated by magnetic shielding.

Shielding around an analog meter is meant to block stray magnetic fields from influencing its measurement. An analog meter often relies on a moving coil in a magnetic field; external magnetic fields from nearby equipment or power lines can couple into that field and exert an extra torque on the coil, causing the needle to deflect or drift inaccurately. A shield made of high-permeability material provides a path for magnetic flux, keeping most of the external field out of the meter’s interior so the indication reflects only the actual signal. Temperature drift, vibration, and some forms of electrical noise involve other causes of error and aren’t primarily mitigated by magnetic shielding.