Overcurrent Protection - Siemens siprotec 7SA6 User Manual

10.9

Overcurrent Protection

Operating Modes
Characteristics
High Set Stages
7SA6 Manual
C53000-G1176-C133-1
As emergency overcurrent protection or back-up overcurrent protection:
Emergency overcurrent protection
Back-up overcurrent protection
Definite time stages
Inverse time stage
Pickup values
Time delays
Drop-off to pick-up ratio
Pick-up time
Drop-off time
Tolerances
The set times are pure delay times.
1
) Secondary values based on I
operates on failure of the measured
voltage,
– on trip of a voltage secondary miniature
circuit breaker (via binary input)
– on detection of a fuse failure in the
voltage secondary circuit
operates independent on any events
(definite) I >>,3I
Ph
(IDMT) I , 3I
P 0P
one of the characteristics according to
Figure 10-1 to 10-3 (see Section 10.5)
can be selected
I >> (phases) 0.10 A to 25.00 A
Ph
or ∞ (ineffective)
3I >> (earth) 0.05 A to 25.00 A
0
or ∞ (ineffective)
T (phases) 0.00 s to 30.00 s
IPh>
or ∞ (ineffective)
T (earth) 0.00 s to 30.00 s
3I0>>
or ∞ (ineffective)
approx. 0.95 for I/I
approx. 25 ms
approx. 30 ms
currents 3 % of set value or 1% nominal current
times 1 % of set value or 10 ms
= 1 A; for I = 5 A they must be multiplied by 5.
N N
Technical Data
>>, I >, 3I >
0 Ph 0
1
) (steps 0.01 A)
1
) (steps 0.01 A)
(steps 0.01 s)
(steps 0.01 s)
≥ 0.5
N
10-25