Secondary instruments: - Gives reading directly of the quantity being measured. - Calibrated with respect to absolute instruments
Classification of Secondary instruments:
1. Depending on the principle of operation: i) Magnetic meters ii) Induction meters iii) Hot wire meters iv) Electrostatic meters
2. Depending on construction: i) Indicating instruments ii) Recording instruments iii) Integrating instruments
3. Depending on permissible error: i) Standard meters ii) Substandard meters iii) First grade instruments.