B0431
Emax X1-Tmax T7-Tmax T8
35/66
Doc N°
Mod.
Apparatus
Scale
Page No
1SDH000587R0002
The percentage of current unbalance is calculated in the following way:
% Unbal =
100
max
min
max
.
−
I
I
I
where I
max
is the maximum and I
min
the minimum phase current.
Unbalance percentage is calculated as follows
)
,
,
(
)
,
,
(
31
23
12
31
23
12
i
V
V
V
d
Mean
V
V
V
d
Voltage unbalance =
i
Max. deviation from mean
.
Besides normal time delay and trip operation, the protection setting for voltage monitoring can, with Vaux or powering via the
PR330/V module, be in such a state of alarm as to be unable to activate the immediate trip: this is because the voltage fault may
persist even when the circuit-breaker is open. In view of the alarm state, the opening command is transmitted immediately when
circuit-breaker closing or the passage of current are detected.
The trip command of the protection can be disabled: in this case, CB opening is not controlled and the condition is merely
signalled by leds and a message on the display.
WARNING: When the value of the phase current is above 6xIn, the function “U” excludes itself because, in this
case, the other protections intervene because the fault is considered as a phase fault.
The protection is not enabled for maximum phase current values lower than 0.3xIn.
3.6.12. Protection “UV”
The excludable, fixed time (t=k), adjustable protection is activated with both self-supply and auxiliary power:
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.
As already described for protection U, the function acts in the same way if an Alarm occurs (opening depending on the state of
the CB and the presence of current) and the trip can be disabled.
3.6.13. Protection "OV"
The excludable, fixed time (t=k), adjustable protection is activated with both self-supply and auxiliary power:
When the maximum phase voltage exceeds the set threshold U
9
the protection counts down the preset time interval t
9
and then
opens.
As already described for protection U, the function acts in the same way if an Alarm occurs (opening depending on the state of
the CB and the presence of current) and the trip can be disabled.
3.6.14. Protection "RV"
The excludable, fixed time (t=k), adjustable protection is activated with both self-supply and auxiliary power:
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
This protection is available on 4-pole or 3-pole CBs with neutral voltage available (see circuit diagram 48). On 3-pole CBs, pres-
ence of neutral voltage must be set by the “neutral voltage present” parameter.
As already described for protection U, the function acts in the same way if an Alarm occurs (opening depending on the state of
the CB and the presence of current) and the trip can be disabled.
3.6.15. Protection "RP"
The excludable, fixed time (t=k), adjustable protection is activated with both self-supply and auxiliary power:
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 rated power of the circuit-breaker (3 Vn*In).
As already described for protection U, the function acts in the same way if an Alarm occurs (opening depending on the state of
the CB and the presence of current) and the trip can be disabled.
3.6.16. Protection "UF" and "OF"
The frequency protections detect variations in the network frequency above (f
12
, t
12
) or below (f
13
, t
13
) an adjustable threshold,
thereby generating an alarm or opening the circuit-breaker.
3.6.17. Protection "T"
A sensor inside the protection release signals abnormal temperature conditions which could lead to temporary or continuous
faults in the electronic components of the unit.
B1751
