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4 Protection "G"
This protection can disabled; can the fixed time (t=k) inverse time (t= k/i2) type; the latter case, the trip time given the expression:
* t,
where l/l4
If the fault current and I4the protection threshold, established the user.
The trip time the release surely 100% the time selected after time has elapsed from the last overload last trip, else trip time will
be reduced depending the overload and time elapsed. This based the "tS" parameter
defined the trip time the curve (t2) selected 1.25x11. The first one only effective when the release powered (it also records
overloads that have not lasted long enough trip the release); the second operates even when the release not powered, reducing any trip
times when closes again straight after and enabled soon the circuit-breaker tripped. The
fault current defined the following formula:
I n
If the circuit reveals faults, the module the sum these currents always nil; vice versa, the value the fault current takes larger and
larger value depending the entity the fault.
The PR121/P release determines which one use according the situation.2 Protection "S"
This protection can disabled; can the fixed time (t=k) inverse time (t=k/I2) type; the latter case, the trip time given the expression:
100-1,
(I,)2
If the fault current and I2the protection threshold, established the user.
NB: Time expressed seconds.6. based the parameter defined trip time the curve (t1) selected
@1.
The PR121/P unit can provide earth fault protection, achieved inside the relay vectorially adding together the phase and neutral currents.6Description the protection functions
12.
The inverse-time protection trip time given the expression:
9 t
max
(I, /I,)2
1 where 12ln, where 12ln
If the fault current and I1the protection threshold, established the user. 12.12.
33/158
.1.1).1 Protection "L"
The "L" the only protection that cannot disabled because for self-protection against overloading the relay itself.2.5xI2.
max
12.6.2.
NB: Time expressed seconds. The other characteristics are the same those for thermal memory "L" (see par.
PR121/P equipped with two instruments make this thermal memory.
1 tio I"
This protection can disabled; the fixed time (t=k) type, and designed for nil intentional delay.1 Thermal ory "L"
The thermal memory function can enabled protect the cables.
Model 2234 Apparatus Scale
L 2778
Doc No- 2
Page No.6.1.6.2.
12.
where \max
1 "
The thermal memory function can enabled for cable protection when the curve with inverse time selected.2.
12.
NB: Time expressed seconds.
When the protection tripped, the circuit-breaker opened the opening solenoid (TC).
12.6.6. This function can enabled through PR010/T, SD-Testbus2 SD-Pocket.2.2.5 Protection against instantaneous sho rt-circuit "linst"
This function has single fixed-time protection curve.2.
The type curve that can set /I2
