State three[3] merits of moving iron type power factor over electrodynamic type

1. Moving type iron power has a large number of turns in order to produce sufficient ampere-turns.
2. The coil has comparatively fewer turns of thick wire so that the ammeter has low resistance and connected in series.
3. In case of voltmeter, it has high impedance so as to draw small current and connected in parallel.

List four advantages of watt-hour meter

1. Accurate and precise measurement
2. Cost is low
3. Reliable
4. Simple construction
5. Highly accurate