L2234
Emax
84/158
Model
Scale
Page No.
Doc. No.
Apparatus
1SDH000460R0002
L2778
N.B.:
In the event of Warning and Alarm, the display is momentarily turned off, to preserve its functionality.
The monitored temperature is not visible on the display.
The protection is always active, both with auxiliary supply and in self-powering.
Disabling the Trip control of the protection means that the PR123/P unit could work, with the circuit-breaker closed, in a range
of temperatures where correct operation of the electronics is not guaranteed.
14.2.9.10 Load control function
Single loads can be enabled/disabled on the load side before the overload protection L intervenes and trips the circuit-breaker on the supply
side. This is done by contactors or switch-disconnectors (wired outside the release), controlled by the PR123/P by means of contacts on the PR120/
K module or on the PR021/K external unit.
The current thresholds are lower than those available with the protection L, so that the load control can be used to prevent tripping due to overloads.
The function is active when an auxiliary power supply or power by PR120/V module is present (see par. 15.1.4).
The operating logic involves the activation of three contacts when the preset thresholds LC1, LC2 and I
w
are exceeded.
Thresholds LC1 and LC2 are expressed as a percentage of I
1
(current threshold specified for protection L) while the "warning current" I
w
is expressed
as an absolute value. The allowable values are given in the following table:
Warning current Iw
0.30 ÷ 10.00 step 0.05xIn
Threshold LC1
50% ÷ 100% step 1% xI
1
Threshold LC2
50% ÷ 100% step 1% xI
1
From the PR123/P you can associate each of the PR120/K or PR121/K contacts with a configuration (NO or NC), a delay and any latch.
14.2.9.11 Voltage protections “UV”, “OV”, “RV”, “U”
The PR123/P unit provides 4 voltage protections, which can be disabled, with fixed adjustable time (t = k), active both with self-powering and
with auxiliary supply:
– Undervoltage “UV”
– Overvoltage “OV”
– Residual voltage “RV”
– Unbalance of line voltage "U".
The protections work on the line voltages. The threshold voltages indicated refer to the line voltage.
Apart from the normal timing and "TRIP" operation, the voltage protections can be in a state defined as "alarm" (with the "emergency" led on and
an alarm message displayed) providing there is an auxiliary or PR120/V module power supply. In fact, in the case where the circuit-breaker is
open and no current is detected, the timing leads to the "alarm" state and not to "TRIP". This is because the fault linked to the voltages can persist
even with the circuit-breaker open and the unit would therefore always be under "timing". When the circuit-breaker is closed or the passage of
a current is detected, you pass immediately from the state of "alarm" to "TRIP" without timing (see par. 14.3.2).
14.2.9.11.1 Protection “UV”
When the minimum phase voltage drops below the set threshold U
8
the protection counts down the preset time interval t
8
and then opens.
14.2.9.11.2 Protection “OV”
When the maximum phase voltage exceeds the set threshold U
9
the protection counts down the preset time interval t
9
and then opens.
14.2.9.11.3 Protection “RV”
When the residual voltage exceeds the set threshold U
10
the protection counts down the preset time interval t
10
and then opens.
The residual voltage U
0
is calculated by vectorially summing the phase voltages. It is therefore defined by the following formula:
3
2
1
0
U
U
U
U
+
+
=
14.2.9.11.4 Protection “U”
The disable-type, fixed-time protection trips when – for a time higher or equal to time
t6
set – an unbalance is detected between two or more line
voltages higher than the set
I6
threshold. Range: 2 … 90% by 1% steps.
The percentage of unbalance is therefore calculated:
)
,
,
(
)
,
,
(
.
31
23
12
1
31
23
12
1
V
V
V
d
mean
V
V
V
d
mean
from
deviation
Max
unbalance
Voltage
=
.
14.2.9.12 Protection against reverse active power “RP”
The PR123/P unit provides protection (which can be disabled) with an adjustable fixed time (t = k), against reverse active power, active both with
self-powering and auxiliary supply.
When the total reverse active power (sum of the power of the 3 phases) exceeds the set reverse active power threshold P
11
the protection counts
down the preset time interval t
11
and then opens.
The minus sign ('-') in front of the threshold and power indicates reverse power. The threshold is indicated as a percentage of "Pn", where "Pn"
is the nominal power of the circuit-breaker (3 Vn*In).
14.2.9.13 Frequency protections "UF", "OF"
The frequency protections record the mains frequency variations above an adjustable threshold (f
12
, t
12
) or below (f
13
, t
13
), generating an alarm
or the opening of the circuit-breaker.
