It is used to measure the applied frequency, functionally similar to vibrating reed meter. The meter incorporates light emitting diodes LEDs which are used instead of vibrating reeds to indicate applied frequency. The frequency is determined by blinking LEDs. When applied frequency matches with the frequency marked on the dial, that particular LED blinks with maximum intensity. When the applied frequency is mid way between two adjacent LEDs, both LEDs blink. When the meter is switched on all the LEDs glow sequentially for a period of 1 to 1.5 seconds, thereafter it will indicate the applied frequency.
All voltage ranges are available in single meter. Terminal screws with washers are provided only for specific voltage as per requirement & remaining two terminals are covered with insulated caps. In case of 96mm & 144mm instruments, two sets of LEDs with the same scale range can be offered, giving two independent meters in one casing (Dual Scale). This facilitates in comparing the frequency of two voltage supplies for paralleling operation.