Voltage Protection: Phase Under/Over Voltage (27/59); Figure 3-22 Logic Diagram: Thermal Overload Protection (49) - Siemens 7SR10 Argus Series Manual

49 Overload Setting I is expressed as a multiple of the relay nominal current and is equivalent to the factor k.I
θ
as defined in the IEC 60255-149 thermal operating characteristics. It is the value of current above which 100% of
thermal capacity will be reached after a period of time and it is therefore normally set slightly above the full load
current of the protected device.
The thermal state may be reset from the fascia or externally via a binary input.
Thermal overload protection can be inhibited from:
Inhibit 49
A binary or virtual input.
49 Therm. Overload
Enabled
Disabled
Inhibit 49
Reset 49

Figure 3-22 Logic Diagram: Thermal Overload Protection (49)

3.4.9

Voltage Protection: Phase Under/Over Voltage (27/59)

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
27/59-n VTSInhibit: Yes
27/59-n U/V Guarded
©2018 Siemens Protection Devices Limited
49 Overload Setting
49 Time Constant
49 Capacity Alarm
&
c
r
cap alarm
IL1
cap alarm
IL2
cap alarm
IL3
A binary or virtual input.
Operation of the VT Supervision function
Under voltage guard element.
trip
trip
trip
7SR10 Description of Operation
1
49 Alarm
1
49 Trip
Chapter 1 Page 44 of 77
B