Specifications

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Doc. no.
Model
Apparatus
Scale
Page No
1SDH000460R0002
L5439
14.2.9.9. Protection against overtemperature inside the relay “OT”
There is a sensor inside the PR123/P unit that monitors the temperature of the unit.
This enables the signalling of any abnormal temperature conditions, which could cause temporary or continuous malfunctions
of the unit’s electronic components.
This protection has two states of operation:
State of “WARNING TEMPERATURE” with
–25°C < temp. < -20°C
or
70°C < temp. < 85°C
: the display is turned
off and the “WARNING” LED flashes at 0.5Hz
State of “ALARM TEMPERATURE” with
temp. < –25°C
or
temp. > 85°C
: the display is turned off, the “WARN-
ING” and “ALARM” leds flash at 2Hz and Trip is activated (if enabled by means of the “Over Temper. Trip = On” parameter).
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.
WARNING: 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 Iw are exceeded.
Thresholds LC1 and LC2 are expressed as a percentage of I1 (current threshold specified for protection L) while the “warning
current” Iw is expressed as an absolute value. The allowable values are given in the following table:
Threshold LC1 50%...100% x I1 step 1% I1
Threshold LC2 50%...100% x I1 step 1% I1
Threshold Iw 0,3 ...10,0 x In step 0,05 In
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 “emer-
gency” 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:
3210
UUUU ++=
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
),,(
),,(
312312
312312
i
VVVdMean
VVVd
Voltage unbalance =
i
Max. deviation from mean
.
Note: alternatively to the “U” current unbalance protection.