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V01225

All Poles Dead

VTS I> Inhibit

VAB

VBC

Hardcoded threshold

I2>1 Current Set

Delta IA

Delta IB

Delta IC

Hardcoded threshold

Any Pole Dead

VTS Reset Mode

Manual

Auto

MCB/VTS

VTS Status

Indication

Blocking

VTS Acc Ind

VTS Slow Block

VTS Fast Block

VT Fail Alarm

Hardcoded threshold

Note: This diagram does not show all stages . Other stages follow similar principles.

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

For the P643 and P645, a 3-phase V

T 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 Chapter 14 - Supervision

P64x-TM-EN-1.3 289

GE P642 User Manual

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