Question

The meter is only connected to one of the lines supplying power when using a(n) ______________ ammeter.

Answer 1

Clamp on meters.

Clamp meters works on the principle of magnetic induction for measurements of alternating current.According to Faraday law Electric current flowing through a wire produces a magnetic field. Since alternating current frequently polarity gets reversed which causes sinusoidal variations in the magnetic field proportional to the current flow. A current transformer placed inside clamp meter would calculate these reversal of magnetic cycles and converts the value to an AC current reading. This principle is used for measuring very high AC currents. The basic main advantage is it can merely be clamped on without any disturbance in the circuit.

Direct current, flows through conductors in a fixed polarity.Hence , the magnetic field around the conductor does not induce any magnetic fluctuations and AC clamp meters will register no reading. DC clamp meters work on the principle of the Hall Effect. Hall effect sensors sense the magnetic field caused by current flow which causes a small voltage across the Hall effect .That voltage, which is proportional to current is amplified and measured , which is obtained on the screen as digital numbers.

with sufficient converters being used like amps to voltage, voltage reading can be obtained , consequently the resistance of the conductors. A image of the basic clamp meter is hereby attached.