Frequency Trend Relay

Silent Features

Low burden

Wide operating voltage range

Wide frequency setting range 39.00 to 70.00 Hz

Independently adjustable tripping stages two of which have a rate of change of frequency function.

Consistent accuracy = +-0.03 Hz at 50 Hz

Unaffected by voltage fluctuations

Insensitive to harmonics & Transient

Built in self-test mode

Built in timer .02 to .18 sec

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

Technical Data

AC voltage rating 110, 220VAC

Auxiliary supplyvoltage From PT 66 to 135 V External 35 to 135 of PT

Frequency setting range 39.0 to 60.0 Hz in step of 1 Hz

Under frequency setting (dfdt) 1 Hz Sec to 9.9 H:: Sec at 50 Hz

Operating voltage range

66 to 135

35-to 135 V

The relay is blocked below & above this limit

No. of tripped stageUFTR -51

UFTR-41

UFTR-6 I

4. Two of which have dfdt output

One of which have dfdt output

4 No. of dfdt output

Reference frequency 5 MHz

Accuracy .03 Hz at 50 Hz

Reset ratio 100% (Digital)

Max reset time under &Overfrequency 50 ms

Tripping delay for dfdt stage 5 cs to 9 cs unless stated set to 6 cs on delivery

Evaluation period for delivery dfdt stages 26 52 mSunless stated set to 26 mS On

Burden

Aux Supply from PT 1.5VA

Aux supply from an external source

Aux DC /without tripping relays

1.5VA max at 150V 50Hz

Contacts in relay

11 W for 4 stages

Indicating signals

1 Pair of N/O reed contact 50VA max

2.5 Ad. C.

Test voltage

Low voltage inhibit LED

LED tripping LED push button reset

Reduced values are valid in case of repeat testing

2KV 50 Hz 1 min

5KV 1.2/50 usec

Casting

Does not apply to the terminal connected

to a common Aux supply

Guaranteed operation Ambient

Flush mounting withrear connection

110 mmx 205mmx 250mm

W H D

temperature -5 – 55`C

Silent Features

Low burden

Wide operating voltage range

Wide frequency setting range 39.00 to 70.00 Hz

Independently adjustable tripping stages two of which have a rate of change of frequency function.

Consistent accuracy = +-0.03 Hz at 50 Hz

Unaffected by voltage fluctuations

Insensitive to harmonics & Transient

Built in self-test mode

Built in timer .02 to .18 sec.