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NB: Time expressed seconds.2.2.25x11.
The PR121/P unit can provide earth fault protection, achieved inside the relay vectorially adding together the phase and neutral currents.
12.
1 tio I"
This protection can disabled; the fixed time (t=k) type, and designed for nil intentional delay.2.
PR121/P equipped with two instruments make this thermal memory.2. based the parameter defined trip time the curve (t1) selected
@1. The other characteristics are the same those for thermal memory "L" (see par. 12.2.6. 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.6.
Model 2234 Apparatus Scale
L 2778
Doc No- 2
Page No.2.2 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.2.6.6.1 Thermal ory "L"
The thermal memory function can enabled protect the cables.
The type curve that can set /I2.1 Protection "L"
The "L" the only protection that cannot disabled because for self-protection against overloading the relay itself. This function can enabled through PR010/T, SD-Testbus2 SD-Pocket.5 Protection against instantaneous sho rt-circuit "linst"
This function has single fixed-time protection curve.
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.6.
where \max
1 "
The thermal memory function can enabled for cable protection when the curve with inverse time selected.
33/158
.
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.1).1.
max
12.
The PR121/P release determines which one use according the situation.
NB: Time expressed seconds.
12.6Description the protection functions
12.6.5xI2.
When the protection tripped, the circuit-breaker opened the opening solenoid (TC). 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.
12.12. This based the "tS" parameter
defined the trip time the curve (t2) selected 1.1.
NB: Time expressed seconds.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
