Aux Protection Menu - Siemens 7SG164 Ohmega 400 Series Manual

2.4 Aux Protection Menu

Any additional protection elements are programmed in this section.
High Set
Overcurrent high set elements can be enabled or disabled using this setting.
HS Level
The overcurrent setting is applied here. It is set in multiples of the nominal current, I
DISTANCE PROTECTION MENU under the CT Secondary setting.
HS Time Delay
A definite time delay from 0 – 1s can be added to the instantaneous operating time of the high set elements.
Stub Protection
Allows the Stub Protection Element to be enabled or disabled.
SP Level
SP Delay
When the Stub Protection element is enabled, and the Status Input assigned to Enable Stub Protection is
energised, the Stub Protection output will operate if the current is above the SP Level for longer than the SP delay
time.
Switch On To Fault
This setting determines whether the Switch On To Fault protection is enabled or not.
SOTF Mode
The Switch On To Fault feature has two modes of operation. It can be energised from an AC function or a DC
function. The DC SOTF function is energised by the operation of a status input from the CB manual close handle
(i.e. a D.C. signal). The AC SOTF function monitors the line current and voltage (i.e. the AC signals) and thus
cannot be used if the VT is on the busbar side of the relay.
SOTF O/C Operate Level (0.3..4) 0.3
This current setting is used as a minimum value to cause operation of the SOTF function after 25ms of fault
current on all three phases.
VT Supervision
This checks for the security of the VT circuit. It can be enabled or disabled.
VTS Latched Operation
If latched operation is enabled and a VTS operation remains on the system for more than the 'VTS Latch
PU Delay', the VTS alarm and inhibit will not reset when current is detected above the setting. If this is
disabled, the VTS will always reset when current is detected above the VTS setting.
VTS Mode
If the VTS operates it can be selected to give an alarm only or it can inhibit the operation of the impedance
elements.
VTS Phase Fault Inhibit (DISABLED..ENABLED)
During a fault condition the VTS is reset when the zero sequence current exceeds the setting. For a phase-fault
there is no zero sequence current therefore the relay may be inhibited during a phase-fault.
With this setting disabled, the relay will trip for a two-phase VT failure.
With this setting enabled, the relay will remain stable for a two-phase VT failure but will not trip if a phase-fault
occurs during such a failure.
VTS Input Source
VTS operation can be set based on Residual voltage and current or Negative phase sequence quantities.
Note the setting levels detailed below.
VTS Ires Level
VTS Vop Level
When the VTS input source is set to 'Res I/V', the VTS feature operates by measuring the summated voltages of
the healthy system, and comparing this with the measured residual current. The VTS will operate if the relay
detects residual voltage without detecting a corresponding residual current. These settings define the levels of
residual current and voltage used. The default residual voltage setting of 20 volts is suitable for most applications,
but this can be changed to make the function more or less sensitive. Note that the level is set based on the
RESIDUAL voltage and current, i.e. 3Vo and 3Io levels, these are defined as 3x the Zero phase sequence
©2013 Siemens Protection Devices Limited
(DISABLE..ENABLE)
(0.1..35) 4
(0..1000) 0
(DISABLED..ENABLED)
(DISABLED..ENABLED)
(AC SOTF..DC SOTF)
xIn
(DISABLED..ENABLED)
(DISABLED..ENABLED)
(ALARM ONLY..ALARM & INHIBIT) ALARM & INHIBIT
(RES I/V...NPS I/V)
(0.05..2) 0.3
(1..100) 20 V
7SG1641 Ohmega 402 60 Relay Settings
ENABLE
xIn
ms
ENABLED
ENABLED
AC SOTF
ENABLED
ENABLED
ENABLED
Res I/V
xIn
which is set in the
n
Chapter 4 Page 13 of 20