hager h3+ - Page 54

54 6LE005550A
Function of the Energy trip unit
3.3 Measurement function
The power factors and the cos are energy distribution quality indicators. Improving
these indicators facilitates the following:
- Decrease the reactive energy consumption which may reduce penalties related
to electrical consumption costs
- Reduce the cross-section of the cables
- Reduce line losses
- Reduce the voltage drop
- Increase the power available to the transformer.
The exhaustive list of variables calculated according to version 3P or 4P is given in
the following table:
Electrical variable Symbol
Version
3 P
Version
4 P
Power factor per phase PF1, PF2, PF3
– X
Total power factor PFtot
X X
Cos per phase (fundamental power
factor)
cos 1, cos 2, cos 3
– X
Total cos (fundamental power factor) cos tot
X X
Note
The values PF1, PF2, PF3, PFtot, cos 1, cos 2, cos 3 and cos tot depend
on the arithmetic or vector addition convention for reactive and apparent power
(see § 3.3.10 - Setting the reactive and apparent power calculation convention).
PF power factor and cos sign
The Energy trip unit is used to configure the sign convention to be applied to the
power factor and cos values.
Two options are possible:
- IEC Convention: The sign for the power factors and cos follows the active
power sign
- IEEE convention: The sign for the power factors and cos is modified to
indicate whether the electrical system is capacitive (+ sign) or inductive (- sign)
IEC convention
P < 0 P > 0
Q > 0
2
Capacitive
(lead or ahead)
1
Inductive
(lag or delay)
PF < 0
cos < 0
PF > 0
cos > 0
Q < 0
3
Inductive
(lag or delay)
4
Capacitive
(lead or ahead)
PF < 0
cos < 0
PF > 0
cos > 0
The IEC convention is indicated when the equipment downstream of the circuit
breaker can operate in turn as a receiver and as a generator.