7SG164 Ohmega 400 Series Impedance Functions
approximately 2/3 of the minimum operating time of the zone 1 to ensure an adequate time margin for
blocking.
The inhibit signal is available immediately whereas the alarm signal has a time delay, which can be set
from 0-60000ms to prevent nuisance alarms occurring during circuit breaker switching.
The above principle is recommended in applications for the transmission and sub-transmission system
where the maximum residual current is 5% or less of the load current.
VTS ALARM contacts can be selected from the OUTPUT MENU.
In the case of loss of all three-phases of the VT, a contact should be taken from the VT MCB, and
connected to the VT CCTS ISOLATED Status Input of the relay. This will energise the Status Input
when the VT MCB trips.
1.7.4 Settings.
VT Supervision
Disable,
Enable
VTS Mode
Alarm Only /
Alarm & Inhibit
VTS Latched Operation
Disable,
Enable
VTS Phase Fault Inhibit
Disable,
Enable
VTS Input Source
Res V&I
/NPS V&I
VTS Ires Level
0.05..2
(0.3 X In)
VTS Vres Level
1..100
(20)
VTS Latch PU delay
0..60000
(5000)
VTS Alarm delay
0..60000
(100)
Status Inputs:
VT CCTS ISOLATED
Relay Outputs:
VTS ALARM
©2010 Siemens Protection Devices Limited
Chapter 2 Page 18 of 21
