EE4503 Electrical Systems Design

1. EE4503Electrical Systems Design Electrical Equipment and Apparatus

2. Topics • Introduction to Electrical Equipment and Apparatus • Medium Voltage Equipment • Low Voltage Equipment

3. EquipmentDegree of Protection Level: IP • IPxy or IPxyz: IP follow by two or three digit number • x: level of protection against contact or solid material getting into • y: level of protection against liquid • z: level of protection against impact

4. EquipmentDegree of Protection Level: IP http://www.apemswitches.be/1-26428-General-information.php

5. Electrical Equipment and Apparatus • HV Equipment (High Voltage): more than 36kV • MV Equipment (Medium Voltage): 1kV to 36kV • LV Equipment (Low Voltage): less than 1kV

6. Electrical Equipment and Apparatus MV Equipment

7. MV Equipment http://www.geelectrical.com/catalog/buylog/15_BL.pdf

8. MV Equipment Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์

9. MV EquipmentLightning Arrester: LA • Operation • Normal: High Impedance so low Leakage Current • Overvoltage: Impedance Drop so Lightning Current goes to ground • Type: Spark Gap Arrester & Arrester without Spark Gap • Rating: Voltage and Discharge Current

10. MV EquipmentLA: Spark Gap Arrester • Old type, less uses • Components: • Spark Gap • Varistor • SiC-Arrester http://c03.apogee.net/contentplayer/?coursetype=foe&utilityid=northwestern&id=4486

11. MV EquipmentLA: Arrester Without Spark Gap • Components: Strong Non-linear Voltage dependent e.g Zinc Oxide • MO-Arrester • ZnO-Arrester http://zone4info.com/articles/401/constructive-design-of-mo-arresters

12. MV EquipmentDisconnector or Disconnecting Switch (DS) Use to disconnect the circuit • Disconnect high voltage but low (or no) current circuit • If on-load disconnection, require Load Buster • Create large isolating distance for safety ** For safety, interlocks with other devices

13. MV EquipmentDisconnector or Disconnecting Switch (DS) • Manual Operated, Motor Operated, or Pneumatic Drive • Rating: Rated Voltage, Rated Normal Current, Short Circuit Current, BIL

14. MV EquipmentEarthing Switches: ES • Connect the metal parts to ground • discharging extra charge that left in the circuit. • for the safety when maintain the system. • May interlock with other devices e.g. DS • Rating: Rated Voltage, Short Circuit Current, BIL

15. MV EquipmentHigh Voltage High Rupturing Capacity Fuses: HV HRC Fuses • Protect the electrical system from over-current or short-circuit. • Compose of fuse string and material to suppress arcs. • Some have a “Striker Pin” to indicate the disconnecting.

16. MV EquipmentHigh Voltage High Rupturing Capacity Fuses: HV HRC Fuses • Rating: Maximum Operating Voltage Rating, Continuous Current Rating, Short Circuit Current Rating, Selectivity (cooperate more than one safety devices together) • Special Rating for using with motor: Starting Current & Starting Time

17. MV EquipmentSwitch Disconnector or Load Break Switch: SD • Able to disconnect circuit at load current • Contain Arc Suppression • Create large isolating distance for safety • Rating: BIL, Rated Voltage, Rated Operating Current, Rated Breaking Current, Rated Short Circuit Making Current

18. MV EquipmentSD http://www.accessscience.com/search.aspx?rootID=792429 • Arc Suppression • Air • Vacuum • Gas (e.g. SF6) • Operated by Spring

19. MV EquipmentInstrument Transformer http://4hv.org/print.php?plugin:forum.134619 • Voltage Transformer • Current Transformer

20. MV EquipmentVoltage Transformers • Transform the high voltage to the measurable voltage level • Do not SHORT circuit the secondary coil • Rating: Burden, Primary Voltage, Secondary Voltage, Permissible Voltage Stress, Accuracy • Measurement: Class 0.1 = 0.1%, Class 0.5 = 0.5% • Protection: Class 3P = 3%, Class 6P = 6%

21. MV EquipmentCurrent Transformers • Transform the high current to the measurable current level (usually 5A) • Do not OPEN circuit the secondary coil • Some have “OPEN-circuit” protection • Rating: Burden, Primary Current, Secondary Current, Short-circuit Current, Rated Voltage, Accuracy Class

22. MV EquipmentCurrent Transformers • Sometime have two secondary core: protection & measuring cores. • Measuring Core: small saturation factor • Accuracy: Class 0.1 = 0.1%, Class 0.5 = 0.5% • Measuring Core: high saturation factor • Accuracy: Class 5P = 5%, Class 10P = 10% • Accuracy: Class 5P10 = 5% at 10 time rated current

23. MV EquipmentProtective Relay • Detect the event and signal circuit breaker. • Usually need CT & VT • Mechanism • Electromechanical Relays • Solid State Relays • Digital Relays

24. MV EquipmentProtective Relay • Overcurrent Relay (50, 51) • Ground Fault Relay (50N, 51N) • Directional Overcurrent Relay (67) • Directional Ground Fault Relay (67N) • Directional Power Relay (32) • Distance Relay (21) • Differential Relay (87) • Under Voltage Relay (27)

25. MV EquipmentMV Circuit Breaker: MVCB • MVCB is able to break the circuit in the normal load and in the short circuit condition. • MVCB take the order from specific relays to trip.

26. MV EquipmentMV Circuit Breaker: MVCB • Need to suppress arcs: • Vaccum • SF6 • Rating: Voltage, BIL, Nominal Current, Short Circuit Current

27. MV EquipmentMV Contactors • Switch that use for the situation where a lot of open/close circuit happen: e.g. Motor circuit

28. MV EquipmentMV Switchgears • Complete set of switching devices, protection devices, measurement devices. • Use at the incoming of the power system and distribute out on the other side

29. MV EquipmentMV Switchgears http://www.daidongs.com/eng/high-voltage-switchgear.htm • Enclosure • Busbar • Protection Devices • Measurement Devices

30. MV EquipmentMV Switchgears http://metechakir.blogspot.com/2012/05/metal-clad-switchgear-power-systems.html • Cubicle • Compartmented • Metal - Clad

31. MV EquipmentRing Main Unit: RMU http://www.t.optimumalelektrik.com/ring-main-unit-teknik-cizimleri.html • Like Switchgear • Like Selector Switch

32. MV EquipmentTransformer • Bridge to Low Voltage system • Categorized by insulator & heat ventilation • Liquid-immersed Transformer • Oil-type Transformer • Less-Flammable Liquid-insulated Transformer • Dry-Type Transformer

33. MV EquipmentTransformer • Usually contain over-heat protection • Sensors: 3 levels (start ventilation, warning, shutdown) • Temperature-Relay • Protective Enclosure (even dry type) • Cast Resin Transformer: can overload by 30-40% using extra heat ventilation

34. Electrical Equipment and Apparatus LV Equipment

35. LV EquipmentCircuit Breaker • switch and able to disconnect circuit when there is overload or short-circuit • Two main types: • Molded Case Circuit Breaker (MCCB) • Air Circuit Breaker (ACB) • Rating: Continuous Current, Interrupting Capacity

36. LV EquipmentCircuit Breaker - MCCB MCCB is made of strong polymer material. • Miniature Circuit Breaker (MCB) used in the consumer unit: 1, 2 or 3 poles for IC around 3kA to 10kA. • Earth Leakage Circuit Breaker (ELCB) or Residual Current Circuit Breaker: 10mA or 30mA

37. LV EquipmentCircuit Breaker - MCCB • Standard CB:usually around 100AF to 2,500AF and the IC is around 18kA to 30kA • High Interrupting Capacity Circuit Breaker: Used when there is a chance of high short-circuit current. IC is usually very high 25kA to 100kA. • Current Limiting Circuit Breaker: Used for very fast breaking and very high short-circuit current

38. LV EquipmentCircuit Breaker - ACB • Usually large circuit breakers • Two types: • Fixed Type • Drawout

39. LV EquipmentCircuit Breaker – ACB v.s. MCCB http://www.everfarelec.com/index.php/product/Air%20Circuit%20Breaker.html • ACB’s components can be accessed • MCB is required no maintenance • ACB is suitable for large systems when the short circuit current is high

40. LV EquipmentCircuit Breaker – Continuous Current • The amount of current that can pass thru the CB under the given ambient temperature • Usually manufactures usually offer one frame with many rating: • Ampere Frame (AF): maximum rating for the specified structure • Ampere Trip (AT): selected rating for each CB

41. LV EquipmentCircuit Breaker – Interrupting Capacity • Interrupting Capacity (IC) or Breaking Capacity is the maximum short-circuit current that the CB is still functional. • IC has to be tested under many parameters, e.g. voltage, power factor, harmonics, etc.

42. LV EquipmentCircuit Breaker – Tripping Unit • The main function of the CB is to properly trip the system • Thermal – Magnetic • Solid State Trip

43. LV EquipmentCircuit Breaker – Thermal & Magnetic Trip • Thermal (Bimetal) Device: Small Overload about 125% of rated current & Long Time Delay • Electromagnetic Device: Large Overload about 10 times of rated current & Instantaneous Trip Time

44. LV EquipmentCircuit Breaker – Thermal & Magnetic Trip Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์

45. LV EquipmentCircuit Breaker – Thermal & Magnetic Trip http://electrical-engineering-portal.com/how-circuit-breaker-trip-unit-works

46. LV EquipmentCircuit Breaker – Thermal & Magnetic Trip http://electrical-engineering-portal.com/how-circuit-breaker-trip-unit-works

47. LV EquipmentCircuit Breaker – Thermal & Magnetic Trip http://electrical-engineering-portal.com/how-circuit-breaker-trip-unit-works

48. LV EquipmentCircuit Breaker – Solid State Trip • Use electronics to decide the trip action • High accuracy and reliability • Can be configuration tripping pattern in many ways

49. LV EquipmentLow Voltage Fuses • Breaking the circuit by melting the metal when over current. • D-fuse • D0-fuse • NH (HRC) fuse (usually in industries) • Rating: Nominal Current, Nominal Voltage, Short-circuit Current

50. LV EquipmentLow Voltage Fuses – D & D0 Fuse http://www.galco.com/techdoc/brsh/10d27r_dat.pdf