Frequency Trend Relay

ARMO-UFTR Frequency relays are used-to monitor the frequency of an electrical System. Due to inadvertent splitting of inner connection in power system. Isolated areas of the system may become deficient in the generation and frequency of the same may drop considerably giving rise to emergency conditions. In order to maintain control of system under this low frequency emergency,some form of graded load shedding is needed. ARMO-UFTR relay is used to detect such conditions and initiate load shedding to prevent complete system collapse.

Type UFTR-41 consists of two/three definite time fully independent frequency measuring stage and one df/dt stage.

Type UFTR-51 consists of two/three definite time fully independent frequency measuring stage and one df/dt stage.

Separate   Auxiliary relays are provided which get energized after the respective time delays (In case of df/dt the tripping frequency gradient). Tripping indications and reset push button are provided on the front of the relay.

The relays are suitable for any application in industrial plants and to generators where definite time under over frequency protection with df/dt stage is required.

Internal timers are provided for each operating circuits and separate aux relays ensure maximum flexibility of application.

Two terminals are provided for the voltage input to the frequency sensing circuit. The measurement of the frequency is digital for which only the zero-crossing of the system voltage and not its amplitude, are of consequence. The relay is independent of the voltage fluctuations with a wide range. However the system voltage sink below a predetermined value in which the accurate measurement can no longer be expected the under voltage blocking circuit blocks all the outputs