“Draw a 33 kV to 11 kV primary substation single line diagram with a line disconnector, metering CT, 1250 A 33 kV VCB, 20 MVA transformer, 11 kV incomer VCB, transformer differential relay, and three 11 kV outgoing feeders.”
Entenda as decisões por trás dele.
A line disconnector, CT, and 33 kV VCB control the incoming supply.
A 20 MVA transformer establishes the 33/11 kV interface.
The 87T relay identifies transformer internal faults.
Three 630 A VCBs protect distinct 11 kV distribution circuits.
Use this for a conceptual primary substation layout. Real substation design needs detailed CT ratios, protection zones, earthing, and utility standards.
Dúvidas comuns
What does 87T mean?
It is the ANSI function number commonly used for transformer differential protection.
Why are VCBs shown at both transformer sides?
They allow protection and isolation on the HV and MV connections of the transformer.
Is a CT only for metering?
No. Current transformers can supply both metering and protection relays, often through separate cores.