Electrical equipment and apparatus
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Assumption University Thailand EE4503 Electrical Systems Design Electrical Equipment and Apparatus 1 Assumption University Thailand Topics • Introduction to Electrical Equipment and Apparatus • Medium Voltage Equipment • Low Voltage Equipment 2 Assumption University Thailand Equipment Degree 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 3 Assumption University Thailand Equipment Degree of Protection Level: IP http://www.apemswitches.be/1-26428-General-information.php 4 Assumption University Thailand 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 5 Assumption University Thailand Electrical Equipment and Apparatus MV Equipment 6 Assumption University Thailand MV Equipment http://www.geelectrical.com/catalog/buylog/15_BL.pdf 7 Assumption University Thailand MV Equipment Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ 8 Assumption University Thailand MV Equipment Lightning 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 9 Assumption University Thailand MV Equipment LA: Spark Gap Arrester • Old type, less uses • Components: – Spark Gap – Varistor • SiC-Arrester http://c03.apogee.net/contentplayer/?coursetype=foe&utilityid=northwestern&id=4486 10 Assumption University Thailand MV Equipment LA: 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 11 Assumption University Thailand MV Equipment Disconnector 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 12 Assumption University Thailand MV Equipment Disconnector or Disconnecting Switch (DS) • Manual Operated, Motor Operated, or Pneumatic Drive • Rating: Rated Voltage, Rated Normal Current, Short Circuit Current, BIL 13 Assumption University Thailand MV Equipment Earthing 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 14 Assumption University Thailand MV Equipment High Voltage High Rupturing Capacity Fuses: HV HRC Fuses • Protect the electrical system from overcurrent or short-circuit. • Compose of fuse string and material to suppress arcs. • Some have a “Striker Pin” to indicate the disconnecting. 15 Assumption University Thailand MV Equipment High 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 16 Assumption University Thailand MV Equipment Switch 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 17 Assumption University Thailand MV Equipment SD • Arc Suppression – Air – Vacuum – Gas (e.g. SF6) • Operated by Spring http://www.accessscience.com/search.aspx?rootID=792429 18 Assumption University Thailand MV Equipment Instrument Transformer • Voltage Transformer • Current Transformer http://4hv.org/print.php?plugin:forum.134619 19 Assumption University Thailand MV Equipment Voltage 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% 20 Assumption University Thailand MV Equipment Current 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 21 Assumption University Thailand MV Equipment Current 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 22 Assumption University Thailand MV Equipment Protective Relay • Detect the event and signal circuit breaker. • Usually need CT & VT • Mechanism – Electromechanical Relays – Solid State Relays – Digital Relays 23 Assumption University Thailand MV Equipment Protective Relay • Overcurrent Relay (50, 51) • Distance Relay (21) • Ground Fault Relay (50N, 51N) • Differential Relay (87) • Under Voltage Relay (27) • Directional Overcurrent Relay (67) • Directional Ground Fault Relay (67N) • Directional Power Relay (32) 24 Assumption University Thailand MV Equipment MV 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. 25 Assumption University Thailand MV Equipment MV Circuit Breaker: MVCB • Need to suppress arcs: – Vaccum – SF6 • Rating: Voltage, BIL, Nominal Current, Short Circuit Current 26 Assumption University Thailand MV Equipment MV Contactors • Switch that use for the situation where a lot of open/close circuit happen: e.g. Motor circuit 27 Assumption University Thailand MV Equipment MV 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 28 Assumption University Thailand MV Equipment MV Switchgears • Enclosure • Busbar • Protection Devices • Measurement Devices http://www.daidongs.com/eng/high-voltage-switchgear.htm 29 Assumption University Thailand MV Equipment MV Switchgears • Cubicle • Compartmented • Metal - Clad http://metechakir.blogspot.com/2012/05/metal-clad-switchgear-power-systems.html 30 Assumption University Thailand MV Equipment Ring Main Unit: RMU • Like Switchgear • Like Selector Switch http://www.t.optimumalelektrik.com/ring-main-unit-teknik-cizimleri.html 31 Assumption University Thailand MV Equipment Transformer • Bridge to Low Voltage system • Categorized by insulator & heat ventilation – Liquid-immersed Transformer • Oil-type Transformer • Less-Flammable Liquid-insulated Transformer – Dry-Type Transformer 32 Assumption University Thailand MV Equipment Transformer • 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 33 Assumption University Thailand Electrical Equipment and Apparatus LV Equipment 34 Assumption University Thailand LV Equipment Circuit 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 35 Assumption University Thailand LV Equipment Circuit 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 36 Assumption University Thailand LV Equipment Circuit 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 37 Assumption University Thailand LV Equipment Circuit Breaker - ACB • Usually large circuit breakers • Two types: – Fixed Type – Drawout 38 Assumption University Thailand LV Equipment Circuit Breaker – ACB v.s. MCCB • ACB’s components can be accessed • MCB is required no maintenance • ACB is suitable for large systems when the short circuit current is high http://www.everfarelec.com/index.php/product/Air%20Circuit%20Breaker.html 39 Assumption University Thailand LV Equipment Circuit 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 40 Assumption University Thailand LV Equipment Circuit 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. 41 Assumption University Thailand LV Equipment Circuit Breaker – Tripping Unit • The main function of the CB is to properly trip the system – Thermal – Magnetic – Solid State Trip 42 Assumption University Thailand LV Equipment Circuit 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 43 Assumption University Thailand LV Equipment Circuit Breaker – Thermal & Magnetic Trip Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ 44 Assumption University Thailand LV Equipment Circuit Breaker – Thermal & Magnetic Trip http://electrical-engineering-portal.com/how-circuit-breaker-trip-unit-works 45 Assumption University Thailand LV Equipment Circuit Breaker – Thermal & Magnetic Trip http://electrical-engineering-portal.com/how-circuit-breaker-trip-unit-works 46 Assumption University Thailand LV Equipment Circuit Breaker – Thermal & Magnetic Trip http://electrical-engineering-portal.com/how-circuit-breaker-trip-unit-works 47 Assumption University Thailand LV Equipment Circuit Breaker – Solid State Trip • Use electronics to decide the trip action • High accuracy and reliability • Can be configuration tripping pattern in many ways 48 Assumption University Thailand LV Equipment Low 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 49 Assumption University Thailand LV Equipment Low Voltage Fuses – D & D0 Fuse http://www.galco.com/techdoc/brsh/10d27r_dat.pdf 50 Assumption University Thailand LV Equipment Low Voltage Fuses – HRC Fuse • Many sizes (dimensions) • Rated current from 6A to 1,250A • Short-circuit current up to 100kA http://www.hausmanngroup.de/ip/fuses.pdf 51 Assumption University Thailand LV Equipment Panelboards • The equipment that takes the main power in and distributes power out to many feeder. http://www.automatech.co.uk/products/moeller.asp?scid=18&gpcid=1&cid=4 52 Assumption University Thailand LV Equipment Panelboards - components • Enclosures to protect the inside components • Busbars conducts the current to Branch CB and also hold the CB • Circuit Breakers – Main CB – Branch CB: Plug-in unit 53 Assumption University Thailand LV Equipment Panelboards – consumer units • IC is about 10kA • Single phase – 4, 6, 8, 12, 16 branches – Main CB: AT=16, 20, 32, 45, 63, 70, 80, 110A • Three phases – 12, 18, 24, 30, 36, 42 branches 54 Assumption University Thailand LV Equipment Panelboards – industrial units • Three phases – 12, 18, 24, 30, 36, 42 branches • Usually being used as “Load Center” – Main Lugs: is mainly for distributing load – Main Circuit Breaker: complete with main circuit breaker 55 Assumption University Thailand LV Equipment Panelboards – industrial units http://conceptorg.com/techlibrary/PowerTechnology/AC_Load_Centers.pdf 56 Assumption University Thailand LV Equipment Measuring Instruments • Ammeter (I, A) • Voltmeter (V, V) • Frequency Meter (F, Hz) • Power Factor Meter (pf) • Power Meter (kW) • Energy Meter (kW-hr) • Current Transformers • Universal Measuring Device 57 Assumption University Thailand LV Equipment Magnetic Contactors • Switch controlled by electrical power • Rating: Utilization Category – AC1: general load p.f.>0.95 – AC2: slip-ring motor (2.5 x In) – AC3: squirrel cage motor (5 to 7 x In) disconnect at load – AC4: squirrel cage motor (5 to 7 x In) and disconnect at the starting current 58 Assumption University Thailand LV Equipment Magnetic Contactors - usage • Commonly use in the motor starting circuit – Direct-on-line Motor Starter (DOL) – Start-Delta Motor Starter (Y) – Auto Transformer Motor Starter – Resistance Motor Starter 59 Assumption University Thailand LV Equipment Switchboards • Distribution panel that distribute the main power unit (e.g. out of transformer) to the branch circuit • Standard: height around 2 to 2.2m • Enclosure from steel sheet – Protect against physical damage, thermal damage and erosion 60 Assumption University Thailand LV Equipment Switchboards • Busbar attached inside the enclosure • Circuit Breaker: Main CB & Feeder CB • Measuremnet Instrument • Protection device (Ground Fault Protection, Lightning Arrestor) • Follow standards (e.g. IEC60439) 61 Assumption University Thailand LV Equipment Switchboards • Rating: Rated Voltage, Rated Current, Rated Short-Circuit Current http://en.wikipedia.org/wiki/Electric_switchboard 62 Assumption University Thailand LV Equipment Busways or Busduct • Equipment that transmits power from one place to the other http://www.sengchai.com/busduct.html 63 Assumption University Thailand LV Equipment Busway or Busduct • Rating: Indoor or Outdoor usage, Voltage Drop, Rated Current, Short-Circuit Rating • Busway can be reduced as long as the protection is still valid and the extension is no longer than 15.2m (50 ft) 64 Assumption University Thailand Reference • Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ 65
