Vibrating-reed Frequency Meter - Working - Construction - Range - Advantages - Disadvantages | FreelyElectrons
Vibrating-reed Frequency Meter
A vibrating-reed frequency meter is measuring instrument
which is used to measure the frequency of various electric circuits.
It consists of 7 vibrating reeds and each vibrating reed has a specific value.
These reeds vibrate when this frequency meter is connected to supply for the
measurement of frequency. A reed which vibrates more as compared to the other
reeds, the more vibrating reed is considered as frequency reading of a supply
or electric circuit.
Construction
This frequency meter consists of thin flat steel reeds which are
arranged alongside and these reeds are near to the electromagnet. The
electromagnet consists of a laminated armature and a winding
connected with a resistance in series on it. This winding is connected
to the AC supply whose frequency is to be measured. The metallic reeds are 4mm
wide and 0.5 mm thick. These metallic reeds are arranged in a row and consists
of flexible base and these bases carries armature of the electromagnet. These
reeds are colored with white color. These reeds are arranged in ascending order
of frequency on a scale.
Range
These vibrating reed frequency meters consists of small readings from 47 Hz to 53 Hz and 57 Hz to 63 Hz.
Working of Vibrating-reed Frequency Meter
To measure the frequency of the circuit, it is compulsory to
connect the frequency meter to a supply. The electromagnet is connected to the
supply for which frequency is to be measured. The magnetism of the
electromagnet alternates with the same frequency and the electro-magnet exerts
the attracting force on each reed once every half cycle. All reeds start
vibrating but the reed whose frequency is double, vibrates with maximum
amplitude due to mechanical resonance. The vibration of the other reeds is so
small and these are unobservable.
Advantages
Its indications are independent.
Its readings are reliable.
These are cheap.
Disadvantages
The reading is not be observed properly if the frequency
difference is half cycle between the adjacent reeds.
These instruments are not accurate to provide the exact reading
on its scale.