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13.9.
The protection always active, both with auxiliary supply and self-supply.
The protection not enabled for axim phase current values lower than 0.2.
P rotection with external "Source round eturn"
Also called "Source Ground return", this can carried out when there the need check operation machine (transformer, generator or
motor etc.9.6 Protection against phase unbalance "
The protection with fixed time, which can excluded, trips the case when, for time greater than the same the time set, unbalance
is determined between two more phases higher than the set threshold I6. temp.2 Zone selectivity "
The zone selectivity function can enabled providing the fixed time curve selected, and function assured only auxiliary voltage provided.5. °C
temp.
The induced current the winding the toroid proportional the fault current which, this case, only transits the above-mentioned toroid. The fault current defined the following formula:
I N
In the case when the circuit does not show any fault, the module the sum these currents always nil; vice versa the value the fault current
will take increasingly large value depending the size thefault. This operating mode isenabled bydefault. 90% steps..
13.5Hz
State "ALARM TEMPERATURE" with
-2 temp.
N.
The behavior and wiring the function are identical those indicated for zone selectivity "S" (see par.
This enables the signalling any abnormal temperature conditions, which could cause temporary continuous malfunctions the unit's electronic
components. 13.9.
Model 2234 Apparatus Scale
L 2778
Doc No- 2
Page No.
The shield ust earthed both the circuit-breaker side and the toroid side.
I .) which has star-configured windings. 11.
The function behaves exactly the same way the protection "S" (see par.: can used also with for external neutral.3).
1 rt-u "
The start-up function can selected the case where the curve with fixed time selected.
The function can enabled and disabled the protection "G" page.
W hen the value the phase current above 6xIn, the function "U" excludes itse because, case, the other protections
intervene because the fault considered phase fault.
47/158
.
This protection has two states operation:
State "WARNING TEMPERATURE" with
and the "WARNING" LED flashes 0.
The protection assured physically positioning external toroid the cable connected from the star center the machine the earthing
connection point.
■ The monitored temperature not visible the display.
Disabling the Trip control the protection means that the PR122/P unit could ork, ith the circuit-breaker closed, range
o tem peratures here correct operation the electronics not guaranteed.ctio G
This provided inside the relay vectorially summing the phase and neutral currents.
A
The external toroid ust connected the PR122/P means corded shielded o-w ire cable (see note par.3xIn. -20 temp.1 (where the rated current
of the homopolar toroidal transformer; the settings available are 100, 250, 400, 800A).2.2.
To work this mode, "Ground protection" must selected the Circuit-breaker Settings menu.B.
The percentage unbalance therefore calculated %Unb= ------— 100 where the maximum and the minimum phase current.2. Trip On" parameter)
or
N. 13.
1 tio rte "
There sensor inside the PR122/P unit that monitors the temperature the unit.
In that case, for the hole duration the unbalance the ill not opened, but only the condition illbe signaled by
means the "warning" LED lit and arning essage. °C
: the display turned off
: the display turned off,
the "WARNING" and "ALARM" Leds flash 2Hz and the Trip activated (if enabled means the "Over Temper.~ max min ~
It possible disable the trip control the protection ("Enable Trip: Off").2). The minimum allowable threshold for the Gext protection 0.
The PR122/P unit can provide two different types earth fault protection alternative:
It indispensable for the star center connected openly earth and for not used neutral conductor too (as the TNC system),
making protection according the system.2)
w ith length not exceeding 15m.2.9.
Zone selectivity "G" can active the same time zone selectivity "S".B.2. Range: .2..:
■ the event Warning and Alarm, the display turned off, preserve its functionality
