ABB 615 series Technical Manual page 496

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Protection functions

87L provides selective protection for radial, looped and meshed network topologies and

can be used in isolated neutral networks, resistance grounded networks, compensated

(impedance grounded) networks and solidly grounded networks. In a typical network

configuration where the line differential protection scheme is applied, the protected zone,

that is, the line or cable, is fed from two directions.

GUID-E9D80758-16A2-4748-A08C-94C33997E603 V3 EN

Line protection with phase segregated line differential with in-zone

87L can be utilized for various types of network configurations or topologies. Case A

shows the protection of a ring-type distribution network. The network is also used in the

closed ring mode. 87L is used as the main protection for different sections of the feeder.

In case B, the interconnection of two substations is done with parallel lines and each line

is protected with the line differential protection. In case C, the connection line to mid scale

power generation (typical size around 10...50 MVA) is protected with the line differential

function. The protection includes the transformer from the protection field. In case D, the

connection between two substations and a small distribution transformer is located at the

tapped load. The use of 87L is not limited to these applications.

Communication

PROTECTED ZONE

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615 series ANSI

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