Reverse Power Protection :
•When the input to the turbine is failed, the generator continues to rotate as a synchronous motor and draws power from the bus bars.
•Turbine acts as a load on synchronous motor and continues drawing the electrical power.
•During the motoring action of the generator, the power flows from the bus bars to the machine and the conditions in the three phases are balanced.
•Normally the power taken by synchronous motor is low of the order of 2 to 10% of the rated power. Power factor and current depends on excitation level.
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| Circuit Diagram Of Direction Power Relay |
•Hence single element directional power relay (reverse power relay) is used to sense the direction of power flow.
•The CTs for reverse power protection may be either at the neutral end or the bus bar end of the generator winding.
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| Operating Characteristics Of Reverse Power Operation |
•Intentional time lag is provided in the reverse power protection so that the protection does not operate during system disturbances and power swings.
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