VIBRATING REED TYPE FREQUENCY METERS
The element of vibrating reed frequency meter consists of steel reeds which are in the field of an electromagnet and vibrate in resonance with the energizing A.C. of this electromagnet. These are manufactured having 11, 13 or 21 reeds. Only the individual reed, natural frequency of which corresponds with the frequency of the A.C. supply will vibrate at full amplitude indicating the correct frequency on the dial. When two reeds show deflection of the same amplitude the mean between the two gives the correct frequency.
Accuracy: ± 1% as per ISS 1248/83