Siemens 7SR105 Rho - Figure 3-9 Logic Diagram: Phase Difference Phase Unbalance (46 PD)

7SR105 Rho Description of Operation
©2018 Siemens Protection Devices Chapter 1 Page 32 of 57
3.1.4.2 Magnitude Difference Protection
If magnitude difference protection is selected as the method of phase unbalance protection the relay calculates
the magnitude difference relative to the thermal overload setting as follows:
%100×=
θ
Δ
I
I
UnbalancePercentage
The operate equation for inverse time characteristic shown in
Figure 3-7 is implemented as:
m
t
I
I
t ×








=
∆
2
1
θ
Inhibit 46
46
&
I
A
I
B
I
C
Mag.
or
NPS
Magnitude difference (IΔ
)
General Pickup
Pickup
Op.
Enabled
Disabled
Gn 46 Element
Gn 46 Type = Mag. Diff.
Gn
46 Setting
Gn 46 Characteristic
Gn
46
Time Mult
Gn 46 Delay (DTL)
Gn 46 Min Op Time
En
Figure 3-9 Logic Diagram: Phase Difference Phase Unbalance (46PD)