Toshiba GR-200 Series Instruction Manual page 291

Decision of CB open/close status
2.24.1
Circuit-breaker auxiliary-contact is used to state the CB status; a normal-open contact (N/O)
and a normal-close contact (N/C) can be furnished in the CB. Thus, as to the phase-A contact
of the CB, signals "CB1-A_NO_CONT" and "CB1-A_NC_CONT" can be used to represent the
CB status in phase-A (i.e., tripped or closed in phase-A). The PROT_COMM function can decide
the CB status using the both signals; the decision generated will be provided for other
protection functions so that the IED can operate in accordance with the CB status.
Signal option
(i)
As the CB auxiliary-contacts (N/O and/or N/C) may generate the signals, the user should set
the rule for the decision. When the N/O signal is generated but the N/C signal is not generated,
set NO for the scheme switch [CB-Contact] so that the PROT_COMMON function can decide
the CB state using only the N/O. Conversely, the decision should be made with only the N/C,
NC is set for this scheme switch. When both N/O and the N/C used, set Both for the scheme
switch [CB-Contact].
Contact supervision
(ii)
Table 2.24-1 exemplifies the rules between the CB main-contact and the CB auxiliary-contact.
Given that the main-contact is open, the N/O is open and the N/C is closed; however if the both
are open when the main contact is open, we should decide the information generated in the
PROT_COMMON is not true (say, an incorrect signal is generated). The contact supervision
can find the inconsistency in the decisions using the rule of Table 2.24-1.
Table 2.24-1 Main and Auxiliary contacts within CB
Auxiliary contacts
The user should set On for the scheme switch [CB-SV] when the operation of the contact
supervision feature is required; set the time for the setting [TCBSV] to define the monitoring
period, which the user can have an option among 0 to 100 sec.
Main contact
OPEN
OPEN
N/O
CLOSED
N/C
- 272 -
6F2T0200 (0.15)
CLOSED
CLOSED
OPEN
GRE200 (1,2)