Ct Circuit Supervision - NR Electric PCS-9611 Instruction Manual

4 Supervision
setting [VTS.En_SynVT] is set as "1", if the difference between the measured synchro-check
voltage ("Ux") and the setting [Syn.U2n] is greater than 15V for longer than 10s, the alarm
signals [Alm_Device] and [VTS.Alm_SynVT] will be issued, and the LED "ALARM " will be on
at the same time. When the status of the synchro-check VT returns to normal condition, the
alarm will restore automatically 1.25s later.
[79.En_SynChk]
[79.En_DdChk]
|Ux – [Syn.U2n]| > 15V
[VTS.En_SynVT]
Figure 4.2-3 Logic diagram of the synchro-check VTS element
Where:
[VTS.En_SynVT] is the logic setting of the synchro-check VTS function;
[79.En_SynChk] is the logic setting of the synchronism check mode of the auto -recloser;
[79.En_DdChk] is the logic setting of the dead check mode of the auto-recloser.

4.2.8 CT Circuit Supervision

The main purpose of the current transformer supervision (CTS) function is to detect faults in the
secondary circuits of the current transformer and avoid influence on the operation of relevant
protection functions. This current transformer supervision (CTS) function will be in operation at
any time, whether the general fault detection picks up or not.
The criteria of the CTS element are:
1. The calculated zero sequence current is greater than the setting [CTS.3I0_Set];
2. The calculated zero sequence voltage is less than the setting [CTS.3U0_Set].
If a CT circuit failure is detected, the alarm signals [Alm_Device] and [CTS.Alm] will be issued,
and the LED indicator "ALARM " will be on at the same time.
If the fast CT circuit failure is detected, the internal signal [CTS.InstAlm] will be "1" without any
time delay.
The logic diagram of the CTS element is shown as below.
Where:
[CTS.3I0_Set] is the threshold current setting of the CTS element;
[CTS.3U0_Set] is the threshold voltage setting of the CTS element;
4-4
I0 > [CTS.3I0_Set]
Cal
&
U0 < [CTS.3U0_Set]
Cal
[CTS.En]
Figure 4.2-4 Logic diagram of the CTS element
Date: 2014-04-08
10s 0
&
[VTS.Alm_SynVT]
10s 0
[CTS.Alm]
CTS.InstAlm
PCS-9611 Feeder Relay