1 / 13

Unit Transformer

Unit Transformer. Unit transformer are step up transformer which is connected to generating house & step up voltage from 15kV voltage to 132 voltage level as requirement or line design parameter.

sancho
Download Presentation

Unit Transformer

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Unit Transformer • Unit transformer are step up transformer which is connected to generating house & step up voltage from 15kV voltage to 132 voltage level as requirement or line design parameter. • It is just like transformer but connected to unit of the generating house that's why we called it unit transformers. • Transformers used in three-phase systems may consist of a bank of three single-phase transformers or a single three-phase transformer which is wound on a common magnetic core. • In Tongi power plant they use three single phase transformer which make a bank and produce three phase supply. Fig: Unit Transformer used in Tongi plant

  2. Cont. Main transformer specifications: Application standard IEC 60076 Rated parameters Type DFZ-55000/132W2 TH (single-phase composite type) transformer) Cooling type ONAN/ONAF (75%/100%) Frequency 50Hz Impedance voltage 16% Rated power 3×550000kVA Rated voltage 132/√3×(1±8×1.25%)/15kV Wiring Ynd1 Insulation level LI650AC275-LI650AC275/LI105AC45 Rated current 721.69/6350.85A

  3. Instrument Transformer

  4. Current Transformer Current transformers are used for reducing/stepping down a.c. current from higher value to lower value for measurement /protection/control.Typical secondary current of CTs are 5A or 1A r.m.s There are two classes of current transformer: Measuring current transformer Protective current transformer Fig: Current Transformer used in Tongi plant

  5. Cont.. • Here is difference between the protection CT and metering CT in operating conditions… • The CT using for protection will have to carry the fault currents which are 10 times the normal full load current. • The CT used for metering will have to carry only full load current

  6. Voltage transformer Voltage transformers are use for measurement and protection. It stepping down the voltage for the purpose of protection, measurement and control. The primary of voltage transformer is connected directly to power circuit between phase and ground depending upon rated voltage and application. Typical secondary voltage of VTs are 110V or 100V. Fig: Voltage transformer used in Tongi plant

  7. When a fault occurs in the protected circuit, the relay (2) connected to the CT an PT actuates and closes its contacts (6). Current flows from the battery (5) in the trip circuit (4). As the trip coil of the circuit breaker(3) is energized, the circuit breaker operating mechanism is actuated and it operates for the opening operation. The trip circuit

More Related