7SG16 Ohmega 402 60 Commissioning
©2010 Siemens Protection Devices Limited
Chapter 9 Page 12 of 19
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4.3.2 VTS blocking function.
The dynamic performance of the VTS scheme is checked using the state sequencer of the test set to simulate
various conditions as follows.
STATE 1 [1 Second]
STATE 2 [1 Second]
Nominal Current & Voltage on all three phases
Zero Voltage on 2 phases, nominal voltage on third phase.
Nominal balanced 3 phase Current on all three phases.
With the VTS blocking function enabled, the relay should be stable. If, however, the VTS blocking function is
disabled, the protection should trip with the corresponding indication.
VTS Mode : VTS alarm only
TRIP
VTS Mode : VTS alarm and inhibit
NO TRIP
To prove the VTS blocking feature for phase faults, set up the following sequence using the test set.
STATE 1 [1 Second]
STATE 2 [1 Second]
STATE 3 [1 Second]
Nominal Current & Voltage on all
three phases
Zero Volts on 2 phases
Nominal PS Current on all three
phases
Voltage as per State 2
Phase to phase fault current (180
°
phase difference)
In this case there will be no zero sequence current, although a fault has occurred. The relay will see residual
voltage but no residual current and prevent tripping.
VTS Phase Fault Inhibit : Enable
NO TRIP
VTS Phase Fault Inhibit : Disable
TRIP
