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4.2 VOLTAGE DEPENDENT OVERCURRENT LOGIC

V Dep OC V<2 Set

V Dep OC V<1 Set

V Dep OC k Set

I>1 Current Set

Vdep OC Start AB

V Dep OC V<2 Set

I>1 Current Set

V Dep OC k Set

I>1 Current Set

Functional

Operator

V Dep OC Status

VRO I>1

VCO I>1

V Dep OC k Set

V00644

Applied Current

Threshold

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

similar principles.

VAB

Figure 40: Voltage dependant overcurrent logic (Phase A to phase B)

The curr

ent thr

eshold setting for the Overcurrent function is determined by the voltage.

If the voltage is greater than V Dep OC V<1 Set, the normal overcurrent setting I>1 current set is used. this applies

to both VCO and VRO modes.

If the voltage is less than V Dep OC V<1 Set AND it is in VCO mode, the overcurrent setting I>1 current set is

multiplied by the factor set by V Dep OC k set.

If the voltage is less than V Dep OC V<2 Set AND it is in VRO mode, the overcurrent setting I>1 current set is

multiplied by the factor set by V Dep OC k set.

If the voltage is between V Dep OC V<1 Set and V Dep OC V<2 Set AND it is in VRO mode, the overcurrent setting is

multiplied by a functional operator to determine the setting.

4.3 APPLICATION NOTES

4.3.1 SETTING GUIDELINES

The V Dep OC k setting should be set low enough to allow operation for r

emote phase-to-phase faults, typically:

>1 2.

P14x Chapter 6 - Current Protection Functions

P14xEd1-TM-EN-1 107

GE MiCOM P145 Agile User Manual

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