P54x/EN OP/La4 Operation
(OP) 5-126
MiCOM P543, P544, P545 & P546
OP
3.1.4 VTS logic
The relay may respond as follows, on operation of any VTS element:
VTS set to provide alarm indication only;
Optional blocking of voltage dependent protection elements;
Optional conversion of directional overcurrent elements to non-directional protection
(available when set to Blocking mode only). These settings are found in the Function
Links cell of the relevant protection element columns in the menu.
The VTS > Inhibit or VTS 2> Inhibit elements are used to override a VTS block in event of a
fault occurring on the system which could trigger the VTS logic. Once the VTS block has
been established, however, then it would be undesirable for subsequent system faults to
override the block. The VTS block will therefore be latched after a user settable time delay
‘VTS Time Delay’. Once the signal has latched then two methods of resetting are available.
The first is manually via the front panel interface (or remote communications) provided the
VTS condition has been removed and secondly, when in ‘Auto’ mode, by the restoration of
the 3 phase voltages above the phase level detector settings mentioned previously.
A VTS indication will be given after the VTS Time Delay has expired. In the case where the
VTS is set to indicate only the relay may potentially maloperate, depending on which
protection elements are enabled. In this case the VTS indication will be given prior to the
VTS time delay expiring if a trip signal is given.
Figure 80 VTS logic
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