NR Electric PCS-9611, Instruction Manual, Page: 95 / 300

3 Operation Theory
PCS-9611 Feeder Relay
3-59
Date: 2014-04-08
operated successfully.
The auto-reclosing startup logic diagram is shown in Figure 3.17-3 . To prevent the auto-reclosing
startup element from undesired operation, this relay takes the currents into account (the signal
[79.OnLoad]). Only when the circuit breaker has tripped completely, the auto-recloser will be put
into service.
3.17.4 Auto-recloser Check Mode
Three check modes are adopted in this relay: synchronism check mode, dead check mode and
non-check mode. Each mode can be selected through a corresponding logic setting.

Synchronism check mode
The following conditions must be satisfied in the synchro check auto-reclosing function.
1. The protection voltage is greater than the setting [25.U_Lv];
2. The synchro-check voltage is greater than [25.U_Lv] / [25.U_Comp];
3. The voltage difference between the protection voltage and the synchro-check voltage
(
ΔU = |U
Prot
- U
Sy n
× [25.U_Comp]|) is less than the setting [25A.U_Diff];
4. The frequency of protection voltage and the frequency of synchro -check voltage are in
the range f
n
± 5Hz (f
n
: the rated system frequency);
5. The frequency difference between the protection voltage and the synchro-check voltage
(
Δf = |f
Prot
- f
Sy n
|) is less than the setting [25A.f_Diff];
6. The phase angle difference between the protection voltage and the synchro-check
voltage (
Δδ = |Φ
Prot
– (Φ
Sy n
+ [25.phi_Comp])|) is less than the setting [25A.phi_Diff].
For the details about the settings [25.U_Comp] and [25.phi_Comp], see Section 7.4.1 .
If the above conditions are satisfied at the same time for longer than [ 25A.t_SynChk], the
signal of the synchronism check of the auto-recloser
“25A.Ok_SynChk” is issued.
When the reclosing operation is executed, this relay checks the synchronism check closing
conditions in the period of the setting [25A.t_Wait]. If the synchro check closing conditions are
satisfied, this relay will issue the reclosing command.
The logic diagram of the synchronism check element for the auto-recloser is shown as below.
Δδ < [25A.phi_Diff]
ΔU < [25A.U_Diff]
Δf < [25A.f_Diff]
&
U
Prot
> [25.U_Lv]
U
Syn
> [25.U_Lv]/[25.U_Comp]
25A.Ok_SynChk
t
ARSynChk
0
Figure 3.17-5 Logic diagram of the synchr onism check element for AR
Where:
“U
Prot
” is the protection voltage value;