Toshiba GR200 Series Instruction Manual page 70

In order for ZG not to operate against the multi-phase fault, it is possible for the user to
set Block for setting [Z*G-MPFBlk]†. If this operation condition shall not be added in ZG
operation, it is possible to set Non for the setting [Z*G-MPFBlk].
†Note: It is recommended to set [Z*G-MPFBlk]=Block for main protection elements, such
as Zone 1, which need to operate instantaneously. Since operating condition for
Z*G elements is restricted by setting Block, it is desirable to set Non for backup
protection elements, such as a forward looking element and a reverse looking
element, which can operate with a pick-up delay timer to cover remote end;
accordingly, protection measurement and operating condition could be less
restricted.
With regard to the leading-phase-block function, the leading phase ZG element could
operate in the event of a multi-phase fault.
The leading phase ZG element can be blocked by an operation of a ZG*COV element as
shown in scheme logics of the distance protection element described later. For example, when
an A-phase (or B-phase or C-phase) ZG1COV is picked up, an operation of C-phase (or A-phase
or B-phase) Z1G output can be blocked. (Note that the ZG*COV functions as a fault detection
as well as for fault phase detection as described for the multi-phase fault detection logic.) The
similar logics are prepared for other zones as well.
Thus, it is possible to set Non for scheme switch [Z*G-LPBlk] in order not to block the
operation of the leading phase of Z*G.
However, Block can be set for this scheme switch in order to block the operation of Z*G.
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6F2S1915 (0.46)
GRZ200 (Soft 031 & 032)