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5.4.9. Overvoltage U> (59)
Overvoltage function (OV) is used for instant- and time delayed overvoltage protection for various
applications including feeder, lter and machine applications of utilities and industry. Each IED with
voltage protection module has four available instances of the function (U>, U>>, U>>>, U>>>>).
Function measures constantly phase voltage magnitudes or line- to line voltage magnitudes.
Overvoltage protection is based to line- to line fundamental frequency component or to line- to neutral
fundamental frequency component if so chosen. If protection is based to line- to line voltage, during
earth fault in isolated or compensated networks the overvoltage protection is not affected. Blocking
signal and setting group selection controls the operating characteristics of the function during normal
operation.
Outputs of the function are Start Trip and Blocked signals. Setting parameters are static inputs for the
function which are changed only by user input in the setup phase of the function. Overvoltage function
utilizes total of eight separate setting groups which can be selected from one common source.
The function can be operating on instant or time delayed mode. In time delayed mode the operation
can be selected for de nite time or IDMT.
The operational logic consists of input magnitude processing, input magnitude selection, threshold
comparator, block signal check, time delay characteristics and output processing.
Inputs for the function are the operating mode selections, setting parameters and measured and pre-
processed voltage magnitudes and binary input signals. Function outputs START, TRIP and BLOCKED
signals which can be used for direct IO controlling and also for user logic programming. The function
registers its operation into 12 last time-stamped registers and also generates general time stamped
ON/OFF events to the common event buffer from each of the three output signal. In instant operating
mode the function outputs START and TRIP events simultaneously with equivalent time stamp. Time
stamp resolution is 1ms. Function provides also cumulative counters for START, TRIP and BLOCKED
events.
In the following gure is presented the simpli ed function block diagram of the OV function.
Figure. 5.4.9. - 46. Simpli ed function block diagram of the OV function.
Measured input values
Analog voltage measurement values are used by the function. Function block always utilizes peak-to-
peak measurement from samples and the monitored magnitudes are fundamental frequency RMS
values. -20 ms averaged value is used for the pre-fault data.
AQ-T257
Instruction manual
Version: 2.00
© Arcteq Relays Ltd
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