7PG2113/4/5/6 Solkor Description of Operation
4.8 Voltage Protection: Phase Under/Over Voltage (27/59) –
7PG2114/6
In total four under/over voltage elements are provided
27/59-1, 27/59-2, 27/59-3 & 27/59-4.
The relay utilises fundamental frequency RMS voltage for this function. All under/over voltage elements have a
common setting to measure phase to phase
(Ph-Ph)
or phase to neutral
(Ph-N)
voltage using the
Voltage Input
Mode
setting.
Voltage elements can be blocked if all phase voltages fall below the
27/59 U/V Guard
setting.
27/59-n Setting
sets the pick-up voltage level for the element.
The sense of the element (undervoltage or overvoltage) is set by the
27/59-n Operation
setting.
The
27/59-n O/P Phases
setting determines whether the time delay is initiated for operation of any phase or only
when all phases have detected the appropriate voltage condition. An output is given after elapse of the
27/59-n
Delay
setting.
The
27/59-n Hysteresis
setting allows the user to vary the pick-up/drop-off ratio for the element.
Operation of the under/over voltage elements can be inhibited from:
Inhibit 27/59-n
A binary or virtual input.
27/59-n VTSInhibit: Yes
Operation of the VT Supervision function (7PG2115/6).
27/59-n U/V Guarded
Under voltage guard element.
Figure 4.8-1 Logic Diagram: Under/Over Voltage Elements (27/59)
©2010 Siemens Protection Devices Limited Chapter 1 Page 55 of 80