Two sets of batteries (220v), their respective chargers and DC boards shall be used for DC supply to each 400KV control relay and protection panels as DC supply –1 and DC supply-2. Necessary arrangement for Supervision of both the incoming DC Supplies shall be made.
In each duplex type 400KV C&R panel, following circuits shall be connected to DC Supply 1 through suitable MCBs/ HRC fuses: i) Isolator control circuit ii) Synchronising circuit iii) Metering circuit iv) Indication circuit v) Annunciation circuit vi) CB Closing circuit vii) VT Selection circuit & CB Aux. Relay circuit.
In case of failure of DC Supply 1, the above circuits will be fed from DC Supply 2. Changeover can be Automatic (by using changeover contact of power contactor)/Manual (by using Selector switch).
DC supply – 1&2drawn to each duplex type 400KV C&R panel, shall be divided into the following sub circuits. Each sub circuit shall be controlled and monitored with the help of suitable MCBs/HRC Fuses.
CB Trip coil –1 shall be fed from DC supply – 1.
CB Trip coil –2 shall be fed from DC supply – 2
DC Supply -1&2 shall be fed to Protection panel from C&R panel directly. Necessary arrangement for Supervision of both the incoming DC Supplies shall be made. DC supply – 1&2 shall be divided into the following sub circuits. Each sub circuit shall be controlled and monitored with the help of suitable HRC Fuses.
Circuitry for Main –1 protection, over voltage protection and reactor gr.-A protection shall be fed from DC supply – 1
Circuitry for Main – 2 protection and reactor gr. –B protection shall be fed from DC supply –2
Annunciation DC shall be supervised by the Annunciator through auxiliary AC supply of the Annunciator in each panel.
DC distribution for 220KV system
There shall be one DC incomer (220V) for each control and relay panel of 220KV system voltage, fed from D.C. distribution board through a 32Amp. switch fuse unit provided there. Necessary arrangement for Supervision of the incoming DC supply for each panel shall be made. One 16 Amp. rating HRC fuse unit both at +ve and -ve side shall be provided for the D.C. incomer in each panel of 220 KV system.
DC supply in individual panel shall be distributed within the panel as below :
- C.B. remote closing, local operation circuit including auxiliary relay function, C.B. remote and protection trip to trip coil 1 with trip circuit supervision relay shall be through HRC fuse and link.
- C.B. remote and protection trip to trip coil 2 with trip circuit supervision relay through HRC fuse and link.
- Protective relay and P.T. selection circuit with D.C. supervision relay through HRC fuse both at +ve and -ve side.
- Indication circuit through HRC fuse and link.
- Isolator control circuit through MCB.
- D.C. emergency lamp circuit with HRC fuse and link.
- D.C. supply to synchronising socket through links both at +VE & -VE side.
D.C. annunciation bus shall also be teed off from the incomer D.C. bus of 220KV Bus Coupler/Bus Transfer Panel for 220KV annunciation system through 6A HRC fuse both at +ve and -ve side and the same shall run continuously through the entire C&R board for facia annunciation system in respective panels. In addition, Annunciation DC shall be supervised by the Annunciator through auxiliary AC supply of the Annunciator in each panel.
DC distribution for 132KV system
There shall be only one DC incomer (220V) for the entire control and relay panel of 132KV system voltage fed from D.C. distribution board through a 32Amp. switch fuse unit provided there. One 16Amp. rating HRC fuse unit both at +ve and -ve side shall be provided for the D.C. incomer in Bus Transfer (2 bus system)/ Bus Coupler (3 bus system) panel of 132KVsystem.
The above D.C. incoming bus of 132KVCR Panel only shall run continuously in the control and relay board of each system voltage. Individual panel D.C. supply for breaker control, isolator control, supervision and indication of circuit breaker and other protective equipment etc. shall be teed off in each panel from the above D.C. bus through a set of links.
D.C. annunciation bus shall also be teed of from the incomer D.C. bus of 132 KV Bus Transfer (2 bus system)/ Bus Coupler (3 bus system) panel for 132 KV annunciation system through 6A HRC fuse both at +ve and -ve side with necessary D.C. supervision relays and the same shall run continuously through the entire C&R board of each system voltage for facia annunciation system in respective panels. In addition, Annunciation DC shall be supervised by the Annunciator through auxiliary AC supply of the Annunciator in each panel.
DC supply in individual panel shall be distributed within the panel as below:
- CB Remote closing, local operation circuit including auxiliary relay function, C.B. remote and protection trip to trip coil 1 with trip circuit supervision relay shall be through 10A HRC fuse and link.
- CB Remote and protection trip to trip coil 2 with trip circuit supervision relay through 10A HRC fuse and link.
- Protective relay and P.T. selection circuit with D.C. supervision relay through 10A HRC fuse both at +ve and -ve side.
- Indication circuit through 6A HRC fuse and link.
- Isolator control circuit through 10A HRC fuse and link.
- DC Emergency lamp circuit with 2A HRC fuse and link.
- DC Supply to synchronising socket through links both at +VE & -VE side.