2 Functions
220
7SA522 Manual
C53000-G1176-C155-3
Additional Stage
I
stub
When using the Istub protection the pickup thresholds ,SK!678% (address )
and ,!678% (address ) are usually not critical, as this protection function is
only activated when the line isolator is open which implies that every measured current
should represents a fault current. With a 1
1
/
2
–circuit breaker arrangement it is possible
that large short circuit currents flow from busbar A to busbar B or to feeder 2 via the
current transformers. These currents could cause different transformation errors in the
two current transformer sets I
A
and I
B
especially in the saturation range. The protection
should therefore not be set unnecessarily sensitive. If the minimum short circuit cur-
rents on the busbars are known, the pickup threshold ,SK!678% is set somewhat
(approx. 10 %) below the minimum two phase short circuit current, ,!678% is set
below the minimum single-phase current. If only the phase currents are to be moni-
tored, set the pickup value of the earth fault stage to ∞.
The times 7,SK678% (address ) and 7,678% (address ) are set to
0 for this application to prevent the protection from operating while the line isolator is
closed.
If this stage is applied differently, similar considerations as for the other overcurrent
stages apply.
The parameter ,678%7HOHS%, (address ) defines whether the time delays
´!2&,QVW75,3µ (address 7,SK678%) and (address 7,678%) can
be bypassed by the binary input . The binary input (if allocated) is applied to all
stages of the time-overcurrent protection. With ,678%7HOHS%, = <(6 you can set
the I>>> stages to trip immediately after the pickup, only if the binary input is activated.
Set time delays for ,678%7HOHS%, = 12 are always activated.
If the I>>> stage is to trip when switching the line on to a fault with or without a short
delay, 627)7LPH'(/$< (address , see above and refer to Subsection “Gen-
eral”), the parameter ,678%627) (address ) is set to <(6. If using the stub
protection, then set to 12 as the effect of this protection function only depends on the
position of the isolator.
2.11.4 Settings
The table indicates region-specific presettings. Column C (configuration) indicates the
corresponding secondary nominal current of the current transformer.
Addr. Parameter C Setting Options Default Setting Comments
2601 Operating Mode ON:with VT loss
ON:always activ
OFF
ON:with VT loss Operating mode
2610 Iph>> 1A 0.10 .. 25.00 A; ∞ 2.00 A Iph>> Pickup
5A 0.50 .. 125.00 A; ∞ 10.00 A
2611 T Iph>> 0.00 .. 30.00 sec; ∞ 0.30 sec T Iph>> Time delay
2612 3I0>> PICKUP 1A 0.05 .. 25.00 A; ∞ 0.50 A 3I0>> Pickup
5A 0.25 .. 125.00 A; ∞ 2.50 A
2613 T 3I0>> 0.00 .. 30.00 sec; ∞ 2.00 sec T 3I0>> Time delay
2614 I>> Telep/BI NO
YES
YES Instantaneous trip via Tele-
prot./BI
2615 I>> SOTF NO
YES
NO Instantaneous trip after
SwitchOnToFault
To Next Page
Loading...
Need help?
General
