Figure 132: Vts Logic (P643 And P645 With 3-Phase Vts) - GE P642 Technical Manual

P64x
All Poles Dead
IA
VTS I> Inhibit
IB
VTS I> Inhibit
IC
VTS I> Inhibit
VAB
Hardcoded threshold
VBC
Hardcoded threshold
Delta IA
Hardcoded threshold
Delta IB
Hardcoded threshold
Delta IC
Hardcoded threshold
V2
Hardcoded threshold
I2
I2>1 Current Set
VTS Reset Mode
Manual
Auto
MCB/VTS
VTS Status
Indication
Blocking
Any Pole Dead
VTS Acc Ind
V01225

Figure 132: VTS logic (P643 and P645 with 3-phase VTs)

For the P643 and P645, a 3-phase VT is used and each of the input voltages VA, VB and VC are with respect to
earth. For the P642, two single-phase VTs are used and the two input voltages VA and VB are phase-to-phase
voltages
As can be seen from the diagram, the VTS function is inhibited if:
● An All Poles Dead DDB signal is present
A phase overcurrent condition exists
●
A Negative Phase Sequence current exists
●
● If the phase current changes over the period of 1 cycle
The VTS will operate if:
● All three of the input voltages are lower than the VTS Pickup threshold AND the function is not inhibited by
any of the above criteria
● Negative Sequence Voltage is present AND the function is not inhibited by any of the above criteria
P64x-TM-EN-1.3
1
&
1
1 & S
Q
R
&
&
&
1
&
Note: This diagram does not show all stages . Other stages follow similar principles.
S
&
Q
R
1 S
&
R
Chapter 14 - Supervision
1
&
VTS Slow Block
1 &
VTS Fast Block
1
VT Fail Alarm
Q
289