Numerical Under Frequency Relay

A switch is provided to select either an independent made of operation of three or four channels or select the under/over frequency made of operation.

The test switch, tripping indications & reset button are provided on the front of Relay.

The relays are suitable for any application in industrial plants & to generators where definite time under/over frequency protection is required

Internal timers are provided for each operating circuits & separate aux. Relays ensure maximum flexibility of operation.

Internal event recording of last three event. The values of parameters at the moment of tripping are recorded on the display.

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 & 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.

Operations of the relay can be tested by means of a test, button which energies the output relays & LED’s after set time delay with the channels set to under/over frequency operation. Access to the test push button requires removal of the front cover. This test facility should normally only be used with the relay trip circuits isolated

• Low Burden
• Wide operating voltage range
• Wide frequency setting range 39. 00 to 70. 00 Hz
• Independently adjustable tripping stages.
• Consistent accuracy (± .03 Hz)
• Unaffected by voltage fluctuations
• Insensitive to harmonics & transient
• Built in timer(.1 to 99.9 Sec.)
• Built in event recorder for last three events.
• Under frequency & over frequency relay with 2 to 4 frequency stages.
• Adjustable under voltage blocking level.
• Field Adjustable relay rated frequency
• One operate time can give to each frequency stage.
• Protection stages can be separately blocked via internal blocking inputs.