The correct answer is: A. induction
Induction instruments are commonly used in power system measurement because they are accurate, reliable, and relatively inexpensive. They work by measuring the magnetic field produced by an electric current. This type of instrument can be used to measure voltage, current, and power.
Moving coil or iron instruments are also used in power system measurement, but they are not as accurate as induction instruments. They work by measuring the force produced by an electric current on a moving coil. This type of instrument can be used to measure voltage and current.
Rectifier instruments are used to measure alternating current (AC) voltage and current. They work by converting AC to DC, which can then be measured by a moving coil or iron instrument.
Electrostatic instruments are not commonly used in power system measurement because they are not as accurate as other types of instruments. They work by measuring the force produced by two charged plates. This type of instrument can be used to measure voltage.
Here is a more detailed explanation of each option:
- Induction instruments work by measuring the magnetic field produced by an electric current. This type of instrument can be used to measure voltage, current, and power. Induction instruments are accurate, reliable, and relatively inexpensive. They are the most common type of instrument used in power system measurement.
- Moving coil or iron instruments work by measuring the force produced by an electric current on a moving coil. This type of instrument can be used to measure voltage and current. Moving coil or iron instruments are not as accurate as induction instruments, but they are less expensive.
- Rectifier instruments are used to measure alternating current (AC) voltage and current. They work by converting AC to DC, which can then be measured by a moving coil or iron instrument. Rectifier instruments are not as accurate as other types of instruments, but they are useful for measuring AC signals.
- Electrostatic instruments work by measuring the force produced by two charged plates. This type of instrument can be used to measure voltage. Electrostatic instruments are not as accurate as other types of instruments, but they are useful for measuring high voltages.