Siemens SIPROTEC 7SS523 V3.2 Manual page 157

5.5.1.2 Auxiliary and Reference Voltages
5.5.1.3 Measured Value Supervision
The bay unit processor monitors the reference voltages of the measured value detec-
tion, as well as the supply voltages. The protection is suspended if the voltages devi-
ate outside an allowable range; depending on the setting of the parameter BLOCKING
MODE (6305/CU), the blocking is selective or complete; the deviation is reported after
three scanning cycles "15V-superv $00" (FNo. 176.1171/CU),
"5V-superv $00" (FNo. 176.1172/CU), "0V-superv $00" (FNo. 176.1173/
CU) (Figure 5-35, page 140).
The auxiliary voltages in the central unit are monitored by the converters themselves.
Faults are annunciated "15V-superv CU" (FNo. 10420/CU), "24V-superv CU"
10421/CU).
(FNo. Failure or disconnection of the auxiliary voltage automatically
takes the affected device out of service. This status is annunciated via an NC contact.
Transient auxiliary voltage dips of
Depending on the setting of the parameter BLOCKING MODE (6305/CU), a failure of
the auxiliary voltage in a bay unit results in a selective or complete blocking of the pro-
tection system.
The analog input circuits of the bay unit are cyclically monitored from the input trans-
ducers up to the digitalization. This is done by forming the current sum and executing
the following plausibility check:
∆ I = I + I + I + I
L1 L2 L3 E
Σ | I | = | I | + | I | + | I
L1 L2
The measured value monitoring picks up if
| ∆ I | > 0.2 I/I and
N
.
| ∆ I | > k Σ | I |
with k = 0.125 (stabilizing factor)
The pick-up characteristic is shown in Figure 5-36, page 142.
If the supervision detects that the measured values are not plausible, the analog
measuring circuits are assumed to be faulty, the measured value cycle is accordingly
marked and the calculation of the protection algorithms blocked for this cycle. If the
fault prevails longer than 1 s time, the protection system is selectively or completely
blocked and an annunciation "MeasInSup $00" (FNo. 176.1175/CU)
The blocking can only be reset with a warm restart (Figure 5-35, page 140).
≤
50 ms will not influence the unit
| + | I
|
L3 E
C53000-G1176-C182-1
Supervisory Functions
7SS52 V4 Manual
141