ELECTRIC GRID STATION
GRID STATION:
It is a station where multiple inputs/outputs comes and goes , where the voltage is transformed as it is required.
Sources of grid station:
transmission
Power house Grid station
Power houses. Other grid stations.
transmission
transmission
Power station
Grid station
Grid station
transmission transmission
EQIPMENTS OF GRID STATION:
C.Bs Transformer CTS ( current transformer) PTs ( potential transformer) Bus Bar Bus coupler Isolators ( line isolator , bus bar isolator) Earth switches
Lightening arrester Sky wire Rectifier unit Battery room Protection relays ( for T/F: buckles , differential , over current, for line protection: distance , overload , earth fault relay)
220kv/132kv section GIS system:
Gas insulated system have introduced in Pakistan. All 220KV & 132KV yard equipments are insulated with SF6 (sulphur haxafluoride) gas. All operations are carried out from control room. There is much minimum chances to injuries and damage. We can touch insulated equipments. Easy to operate. Efficient system.
220kv/132kv section GIS system:
A device that can switch Automatic during normal or abnormal conditions.
Oil circuit breaker Air circuit breaker
use oil use air
Sf6 circuit breaker use sf6 Vacuum circuit breaker use vacuum
To step up or step down the voltage. Transfer power from one A.C voltage to another A.C voltage at the same frequency.
AUTO T/Fs 220kv and above uses it can be step up &down.
Power T/F 132kv/11kv Distribution T/Fs 11kv/440v &220v
A P.T is used to step down the voltages for measurement, control and protection.
Disconnect any electrical element under no-load condition for safety, isolation and maintenance.
BUSBARS:
A metal strip that is use to interconnections of many electrical elements at a common point ,maintain the specific voltages for transmission and distribution systems.
Bus coupler:
A device that is use to couple two bus bars for requirement.
Sky wires:
A wire that is use to protect the grid station equipments from unwanted high voltage waves and discharge them through earth.
Earth switches:
A wire that is connected to earth. use to isolate the equipments and human beings and protect them from damage.
Protection relays:
Use to protect the all equipments of grid station and transmission and distribution system. Primary protection relays Secondary protection relays
Distance relay
Relay panels
Principles of Distance Relays
The impedance of a transmission line is proportional to its length, for distance measurement it is appropriate to use a relay capable of measuring the impedance of a line up to a predetermined point (the reach point)
OVER Current earth fault relay:
control panels:
use to switching of all transmission and distribution system.
Rectifier unit :
Use to rectify A.C into D.C for protection purposes .
Battery room:
Use to storage D.C and help as back up source for protection system.
11kv section:
11000v received in the 11kv control room for distribution purpose.
Distribution bus bars Feeders Capacitor banks Rectifiers Vacuum circuit breakers Isolator trolleys Meters
11kv section includes:
Relays(over current used on 3 phase) Auxiliary Transformer
Distribution bus bars: Feeders:
Bus bar is used to distribute the electricity . Use to connect different feeders at common point.
Feeders are the out going connections of different areas and industries.
Capacitor banks:
Capacitors are interconnected to each other to improve power factor Secure the system from over loading.
11kv section
Rectifier unit :
Use to rectify A.C into D.C for protection purposes .
Vacuum circuit breakers:
A device that is use to open and close the circuit Automatic during normal or abnormal conditions. Vacuum gas is use to quench arc of C.B contacts .
11kv section
Isolator trolleys:
Isolator trolley turn out when the line man workers required the conformation that circuit is open.
11kv section
Measurement Meters:
Ampere meters kwh meters
Protection relays:
During fault Relay sense the fault and give signal to V.C.B and V.C.B remove faulty circuit .
Over current relays . VAX relays
11kv section
Over current relays :
Sense the fault due to over current flow in circuit. Phase to phase phase to ground
VAX relays :
Auxiliary Transformer:
This transformer receive the 11kv and step down T/F that provides 400 volts A.C. This is use to supply electricity to all grid station system.
VAX relays :
Working of transmission and distribution system
Control centers Npcc
Rcc
Pdc
DISTRIBUTION OF ELECTRICITY:
Many equipments are used for distribution process
