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9.2 Protection "S"
This protection can disabled; can the fixed time (t=k) inverse time (t= k/i2); the latter case, the trip time given the expression:
max where where the fault current and /2,the protection threshold. The first only effective when the release powered (it also records
overloads that have not lasted long enough trip the release), while the second works even when the release not powered, reducing any trip
times the case immediate reclosing and enabled soon the tripped. for type slope and 13.9.2.1.2.
Standard trip curve according IEC 60255-3
There are types curves settable, defined the IEC standard 60255-3 and C..
NB: The thermal memory function can only set the type curve selected the standard one (t=k/I2) (see par.. 30s, with steps 0.2.01s.5xI2. The types trip curves
settable are divided into two groups according the standard they refer to. based the parameter defined the trip time the curve (t1) selected
at 1.1.
( H
NB: Time expressed seconds.1).1.
The protection trip time inverse time given the expression:
k f
t ------------- where —
( A
NB: Time expressed seconds.
Range: 0.9. This based the
"tS" parameter defined the trip time the curve (t2) selected 1. Otherwise,
the trip time will reduced, depending the overload which has occurred and the time that has elapsed. The other characteristics are the same those for thermal memory
"L" (see par.
where the fault current and the protection threshold specified the user. 13.5);
b parameter introduced SACE increase the number curves with the same slope.2 Start-up threshold "S"
The start-up function can selected the case where the curve with fixed time selected. 2
Page No.9Description the protection functions
13.1 Protection "L"
The "L" the only protection that cannot disabled because for self-protection against overloading the relay itself.2.
The PR122/P fitted with two instruments make this thermal memory.
100-12
• Start-up tim e
The start-up time common all the protections involved.
13.2.25xI1.2.
The release trip time certainly 100% the one selected, after interval has passed since the last overload since the last trip. the fault current and the protection threshold.
13.
Standard trip curve according IEC 60947-2
Only one type curve settable (t=k/I2) defined the IEC standard 60947-2. No. new start-up possible
after the current has dropped below this threshold.
a andk are two parameters, suggested the standard, which vary the type slope selected (e.
45/158
.
Model 2234 Apparatus Scale
L 2778
Doc..1).1s .1 Thermal ory "L"
The thermal memory function can enabled for cable protection.9.13.9.
1 herm ory "
The thermal memory function can enabled for cable protection the case where the curve with inverse time selected..g. This parameter automatically calculated setting
parameter (required trip time 3xI1).
The start-up function enables the protection threshold (S, and changed during time interval lasting "ts", starting from "start-up".10In, 0.
(I,)2
NB: Time expressed seconds.2.2.
13.1 steps).
It the PR122/P release that automatically decides which the two use, according the various situations. The
latter must intended follows:
- Passage the RMS value the maximum current over one single adjustable threshold (0.
The protection trip time inverse time given the expression:
9 -f
V where 12ln, where 12ln where /,.9. 13.
The function can disabled and setting characteristic the single protection units
