Under the guidance of External guide: M. Venkateswarlu (A.D.E) Internal guide :P.Bapaiah. M.Tech (Asst.prof.)
CONTENTS LAYOUT OF CHILLAKALLU SWITCHGEAR & PROTECTION EQUIPMENT BUS BARS TRANSFORMERS EARTHING PLCC
P.PROL CHILLAKALLU HCL(JPT) COROMANDA TOGARAI KODAD SINGLE LINE DIAGRAM OF 220/132/33KV SUB-STATION, U L 7.2 MVAR CHILLAKALLU HARINI 5 MVAR 5MVAR NANDIGAMA KAKATIYA HCL C.BANK C.BANK TEXTILE SAIL AGRO 220K C.BANK 220KV S V BUS PT -I BUS - I 220KV BUS COUPLE 220KV LA WT R BUS CV CB CT -II T 33KV220KV KONDAPALLI -I 250KVA 100KVA BUS STATION 33KV BUS 33KV STATIO TR - II PT I BUS N PT II TR I 132KV220KV KONAPALLI - NANDIGAM 132KVII 220/132K 220/132KV 132/33KV 132/33KV MCL A V 20/132KV 100MVA 31.5MVA 31.5 MVA 100MVA 100MVA PTR 2 PTR I PTR II PTR-3 PTR-I (TELK) (APEX) (BB) (VIJAI) (BHEL)220KV VTS-1 132KV BUS PT- 1 132KV L BUS A220KV VTS-2 CB220KV CT 132KVNARKETPALLI-1 BUS PT- 2 220KV CVT BUS PT - II220KV NARKETPALLI-2 LA 132KV 132KV 132KV VEPALA 132KV SCR - I KUSUMANCHI MADHIRA 132KV SINGARAM 132KV 132KV 132KV SCR - KHAMMAM KODAD SEETAPURAM II
INSTRUMENT TRASFORMERS These are used to protect apparatus from high voltages and permit use of reasonable insulation level and carrying current capacity in relays and meters. General rating is 5amps and 1amp and 110volts 50 cycles on secondary side.
These are two types Current transformers (CT) Potential transformers (PT)
Current transformers The CT’s are used to step down the current of a circuit to a lower value. The CT steps down the incoming 800amps to 1 amp. These are connected in series to the equipment in the layout.
Potential transformers The PT’S are used to step down the voltage of a circuit to a low value that can be effectively and safely used for operation of instruments. The main two functions of the PT are Measurement Protection These are connected in parallel to the system.
Circuit breakers These are used to operate on the fault either on line or transformer, depending upon where it is connected. This isolates the faulty line or equipments from the live portion of the substation by opening automatically through protective relays; control cables etc. in a definite time.
Types of circuit breakers Based on the medium used A) Air Blast Circuit Breaker B) SF6 Circuit Breaker C) Vacuum Circuit Breaker D) Minimum Oil Circuit Breaker
RELAYS A relay is a device that detects the fault & initiates the operation of the circuit breaker to isolate the defective element from the rest of the system It detects the abnormal conditions by constantly measuring the electrical quantities(voltage ,current , frequency & phase angle)which are different under normal &fault conditions.
Classification of relays A) Based on construction and principle of operation Electromagnetic relays Electromagnetic induction simply induction relays Electro thermal relays Physio-electric relays Static relays / Numerical relays. Electro dynamic relays
B) Based on time of operation Instantaneous relays Definite time-lag relays Inverse time-lag relays Inverse -Definite minimum time lag relays
Lightning arresters Lightning arresters are protective devices for limiting surge voltages due to lightning strikes or equipment faults or other events, to prevent damage to equipment and disruption of service. Also called surge arresters.
Isolators Isolaters are used in addition to circuit breakers These are provided on each side of ckt breaker to provide isolation and enable maintenance. While openining the circuit, the ckt breaker opens first and isolator & while closing the ckt the isolator closed first and then ckt breaker. Types of isolators 1.Single break isolators 2.Double break isolators
Insulator The insulator provide necessary insulation between line and conductor. It acts as support to conductors.Types of insulators a. pin type b. suspension type c. stray type d. shackle type e. stay insulator
The causes for failure of insulatorsare Cracking of insulators Defective insulator material Porosity of the material Improper glaze Flash over Mechanical stress Short circuit
Bus bars Bus bars are nothing but the solid or tabular aluminum conductors Supported on post insulators bus bar are in the generating station and substation form Important link between the incoming and outgoing circulates.
Transformers Transformer is static ac machine which transfers the electric power energy from one electrical circuit to another electrical circuit with same frequency . It works on mutual induction (electro- magnetic induction) principle.
Ratings of transformer in 220kv/132kv/33kv 100MVA 3no’s 31.5MVA 3no’s 250KVA 2no’s
Protection schemes of transformers 1. Differential protection of transformer 2. Over current protection of transformer 3. Earth fault protection of transformer 4. Over-fluxing protection
Earthing Connecting of an electrical equipment or apparatus to earth with the help of a connecting wire of negligible resistance is known as earthing or grounding.Need For Earthing To provide low impedance path to the earth for currents occurring under normal & abnormal conditions.
PLCC The communication and the data transmission from one substation to another substation is carried out by means of power line carrier communication PLCC system. PLCC utilizes high frequency data is transmitted through to power line conductors
It consists of 1. line trap unit 2. Coupling capacitor 3. Tuning unit 4. Transmitter , receiver & other electronic equipment Applications Voice communication Tele Protection Tele metering
Protection for transmitting signal Wave trap or line trap Coupling filter or capacitor voltage Transformer (CVT) Line matching unit Balancing transformer Lightning arrester Earth switch
Wave Trap Wave trap is an inductive device, which offers high impedance to high frequency signals. Hence it will not allow communication signals towards substation equipment. Wave trap offers negligible impedance to power frequencies hence power flow will be unaffected
CVT Capacitor voltage transformer in a substation will be used for protection as well as coupling device in PLCC. CVT offers high impedance to power frequencies. Hence EHV, power cannot enter communication equipment, by the action of low pass filter arrangement.
Conclusion Enabled to know typical substation arrangements. Enabled to know different makers of equipment. Created an interest to go in to the designing field after our graduation.