Figure 263: Differential Cts; Differential Cts Logic - GE MiCOM P40 Agile Technical Manual

Chapter 18 - Supervision
4.2

DIFFERENTIAL CTS LOGIC

Inhibit CTS
Any Trip
Disable CTS
CT1 L i1>
>
CT1 R1 i1>
=
2
CT1 R2 i1>
CT1 L i2/i1>>
CT1 R1 i2/i1>
&
CT1 R2 i2/i1>
CT1 R1 i2 /i1 >>
CT1 L i2/i1>
&
CT1 R2 i2/i1>
CT1 R2 i2/i1 >>
CT1 L i2/i1>
&
CT1 R1 i2/i1>

Figure 263: Differential CTS

4.3 CTS IMPLEMENTATION
If the power system currents are healthy, no zero sequence voltage are derived. However, if one or more of the AC
current inputs are missing, a zero sequence current would be derived, even if the actual power system phase
currents are healthy. Standard CTS works by detecting a derived zero sequence current where there is no
corresponding derived zero sequence voltage.
The voltage transformer connection used must be able to refer zero sequence voltages from the primary to the
secondary side. Therefore, this element should only be enabled where the VT is of a five-limb construction, or
comprises three single-phase units with the primary star point earthed.
476
&
1
CTS Time Delay
CTS Status
Indication
Pickup
CTS Reset Mode
Manual
Auto
CTS Status
Indication
CTS Time Delay
1
Pickup
*
1
CTS Reset Mode
Manual
Auto
S
Q
&
R
CTS Status
Restrain
1
CTS Status
Restrain
&
1
S
Q
&
R
P543i/P545i
CT Fail Alarm
1
&
CTS Block
CTS Restrain
Pickup
&
CTS Block Diff
Remote CT Alarm
*In indication mode , timer is set to 20ms
P54x1i-TM-EN-1
V01262