23 June 2011 6077AC Electrical Systems Safety – Capstone Assessment
Family Name ................................................................................. Given Name ................................................................................... Student Number ........................................................................... Centre ............................................................................................ Signature ....................................................................................... 23 June 2011 6077AC Electrical Systems Safety – Capstone Assessment Time allowed – Three hours plus Ten minutes reading time 29 Pages in this Question Booklet All Questions to be attempted TOTAL MARKS AVAILABLE =100 Aids to be supplied by college • None Aids to be supplied by student • Australian/New Zealand Wiring Rules AS/NZS 3000:2007 (AMDT No 1 – July 2009) • Service and Installation Rules of NSW – NSW Dept. of Water & Energy. • Australian/New Zealand Standard Electrical Installations - Selection of Cables AS/NZS 3008.1.1:2009. Section Possible Marks A 20 B 20 C 45 D 15 Total 100 Achieved Marks • Students own marginal notes, indexing and formal amendments may be included in the above regulatory publications. • Pen, pencil, eraser, rule and calculator. Instructions to Student • Mobile phones are to be turned off and removed from your person. You cannot access a mobile phone during this test. • All questions to be answered in the space provided on this examination paper. Answers to Section A – multi-choice questions, are to be answered on the sheet attached to this examination paper. • You are not to use any other reference book in this examination. • The whole of this paper is to be handed to the teacher upon completion. Aids permitted where indicated: Standard Dictionaries Bilingual Dictionaries Technical Dictionaries Programmable Calculators Non-programmable Calculators Electronic Devices No No No No Yes No - 2 - SECTION A – (20 Marks) INSTRUCTIONS: Select the best answer for the following statements and place an ‘X’ in the appropriate box on the Answer Sheet attached to this examination paper. Each correct answer is worth one (1) mark. QUESTION 1 (1 Mark) The maximum permissible disconnection time for a 40 Amp type ‘C’ circuit breaker protecting a permanently installed motor wired via an isolator is: (a) 400 milliseconds (b) 0.4 hour (c) 1.0 hour (d) 5.0 seconds QUESTION 2 (1 Mark) A customer complains that when they plug an appliance into a particular socket outlet, the RCD immediately trips. Of the following options, the most likely cause of the fault would be: (a) a transposition of the neutral and earth conductors at the socket outlet (b) a transposition of the active and neutral conductors at the socket outlet (c) an open-circuit earth conductor (d) an open circuit active conductor QUESTION 3 (1 Mark) A circuit is wired with 2.5 mm2 TPS twin and earth cable that is clipped to the side of the ceiling joists in a domestic installation where bulk thermal insulation is installed. This circuit would be classified as: (a) likely to be disturbed (b) enclosed in thermal insulation (c) totally surrounded by thermal insulation (d) partially surrounded by thermal insulation QUESTION 4 (1 Mark) The minimum size copper earth conductor for a 3-phase industrial oven supplied by 25mm2 copper active conductors is: (a) 4 mm2 (b) 6 mm2 (c) 10 mm 2 (d) 25 mm2 6077AC MY2011 TAFE NSW - 3 - SECTION A – (Cont’d) QUESTION 5 (1 Mark) The magnetic mechanism of a thermal-magnetic circuit breaker: (a) operates by heating a bi-metal strip. (b) operates on long time overloads only. (c) has a time response suitable for overload protection. (d) has a time response suitable for short-circuit protection. QUESTION 6 (1 Mark) When single-insulated wire is installed in ducting that has a removable lid: (a) the cables must be taped together and held in position (b) the lid must be held in position with cable ties (c) building wire is not permitted in a duct which has a lid (d) the lid shall not be removed without a special tool if the duct is readily accessible QUESTION 7 (1 Mark) A low resistance measured between neutrals of different circuits indicates the probability of: (a) an open circuit neutral (b) a short circuit between neutral and earth (c) a short circuit between active and earth (d) interconnection between the two circuits QUESTION 8 (1 Mark) The primary function of over-current circuit protection in an installation, is to: (a) reduce the effect of electric shock. (b) prevent electric shock. (c) protect the circuit conductors from damage due to overheating. (d) protect the appliance from damage due to overheating. QUESTION 9 (1 Mark) The International Protection Rating (IP) indicates the degree of protection of electrical equipment enclosures against penetration by: (a) hazardous gases (b) solid objects and water (c) unauthorized persons (d) flammable liquids and gases 6077AC MY2011 TAFE NSW - 4 - SECTION A – (Cont’d) QUESTION 10 (1 Mark) The maximum value of current that may flow in the electrical system during a short circuit is the: (a) let through value of current. (b) cut off current. (c) prospective short circuit current. (d) trip or fusing current. QUESTION 11 (1 Mark) When testing the earth continuity it is recommended that: (a) protective earth conductors be disconnected from all appliances (b) protective earth conductors be disconnected from water heaters (c) an insulation resistance tester on the 250V range is used (d) an insulation resistance tester on the 500V range is used. QUESTION 12 (1 Mark) The NSW Service and Installation Rules require that the original notification of the results of all compliance tests, for a completed electrical installation, must be submitted to the appropriate persons/bodies within: (a) 48 hours (b) 1 week (c) 14 days (d) 1 month. QUESTION 13 (1 Mark) The term ‘discrimination’ as applied to circuit protection means: (a) the circuit protection on the main switchboard should be the first to operate. (b) the fuse or circuit breaker with the highest fault current rating should operate first. (c) the circuit protective device closest to the fault or over-current should operate before any upstream devices. (d) the circuit protection should be able to distinguish between a short circuit to earth and a short circuit between live conductors. 6077AC MY2011 TAFE NSW - 5 - SECTION A – (Cont’d) QUESTION 14 (1 Mark) What is the term used in AS/NZS 3000 to describe the maximum demand current for which a circuit is designed: (a) IB (b) IN (c) Iz (d) Isc QUESTION 15 (1 Mark) The minimum IP rating required for a socket outlet installed in a bathroom within the area designated as zone 0 is: (a) IPX4 (b) IPX7 (c) 1P56 (d) socket outlets are not permitted in Zone 0 QUESTION 16 (1 Mark) The insulation resistance tester used to test a three-phase 400 Volt sub-main must be tested by applying a DC voltage of: (a) 250V (b) 500V (c) 750V (d) 1000V QUESTION 17 (1 Mark) What is the minimum depth of cover of a Category A underground wiring system which is to be located below a 150mm concrete slab, and is located within the confines of a building: (a) 300 mm below finished ground level (b) 500 mm below finished ground level (c) 600 mm below finished ground level (d) directly below the concrete slab 6077AC MY2011 TAFE NSW - 6 - SECTION A – (Cont’d) QUESTION 18 (1 Mark) The colour coding used to identify a dry chemical powder fire extinguisher is: (a) red without colour stripe (b) red with white stripe (c) red with black stripe (d) blue without colour stripe QUESTION 19 (1 Mark) To comply with the requirements of AS/NZS 3000, the minimum size equi-potential bonding conductor for bonding the water pipe, when the consumer main is copper 50 mm2, 3-phase and neutral, is: (a) 4.0 mm2 (b) 6.0 mm2 (c) 16.0 mm2 (d) 50.0 mm2 QUESTION 20 (1 Mark) A major hazard with confined spaces is: (a) difficulty in using tools (b) unable to stand upright when working (c) only one person can work at a time (d) flammable contaminants and oxygen depletion 6077AC MY2011 TAFE NSW - 7 - SECTION B – (20 Marks) INSTRUCTIONS: Answer the following questions in the spaces provided. • • Use AS/NZS 3000:2007 to best answer each question. Write clause numbers where required. QUESTION 1 (2 Marks) A circuit for a fixed or stationary cooking appliance incorporating an open cooking surface must have a functional switch. Name three (3) examples of cooking appliances having an open surface? __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________ ) QUESTION 2 (2 Marks) What is the maximum number of circuits that can be connected an individual RCD in a domestic installation is: __________________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________ ) QUESTION 3 (2 Marks) When is it necessary to provide protection for persons and livestock against injury from mechanical movement of electrically actuated equipment? (a) _________________________________________________________________ or (b) _________________________________________________________________ _________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________) 6077AC MY2011 TAFE NSW - 8 - SECTION B – (Cont’d) QUESTION 4 (2 Marks) Specify the four (4) acceptable methods of protection against indirect contact. (a) ________________________________________________________________ (b) ________________________________________________________________ (c) ________________________________________________________________ (d) ________________________________________________________________ ________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________) QUESTION 5 (2 Marks) Where recessed ELV halogen down-lights are installed, what precautions must be made to minimise the temperature rise and prevent the risk of fire caused by heat at the rear of the luminaire? (a) ________________________________________________________________ ________________________________________________________________ ________________________________________________________________ (b) ________________________________________________________________ ________________________________________________________________ (c) ________________________________________________________________ ________________________________________________________________ (d) ________________________________________________________________ ________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________) 6077AC MY2011 TAFE NSW - 9 - SECTION B – (Cont’d) QUESTION 6 (2 Marks) Where consumers mains are not protected on the supply side by short circuit protective devices, the MEN link shall have a cross sectional area not less than that of the? __________________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________ ) QUESTION 7 (2 Marks) When consumer mains have multiple active conductors connected in parallel (e.g. 2 per phase), how is the size of the main earth conductor determined? __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________) QUESTION 8 (2 Marks) At what location should the equipotential bonding conductor be connected to the metallic water service? __________________________________________________________________________ __________________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________) 6077AC MY2011 TAFE NSW - 10 - SECTION B – (Cont’d) QUESTION 9 (2 Marks) A 230 Volt final sub-circuit consists of a V75 rated multi-core cable and supplies a 25A nonRCD protected socket outlet within a commercial computer room. A 25A type ‘C’ circuit breaker protects the circuit. Determine the maximum allowable fault-loop impedance, when supply is available and the complete loop is tested. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ QUESTION 10 (2 Marks) Specify four (4) requirements for connecting the main earth conductor to an earth electrode. (a) ________________________________________________________________ ________________________________________________________________ (b) ________________________________________________________________ ________________________________________________________________ (c) ________________________________________________________________ ________________________________________________________________ (d) ________________________________________________________________ AS/NZS 3000 Reference (Clause number _______________) 6077AC MY2011 TAFE NSW - 11 - SECTION C – (45 Marks) INSTRUCTIONS: This section involves calculations. Show all necessary working in the space provided, marks will be awarded accordingly. Write answers in the spaces provided. QUESTION 1. (5 Marks) A small retail complex consisting of 4 shops at street level (350 m2 each) and 3 offices (250 m2 each) on the first floor. All shops and offices have reverse cycle air conditioning, light and power. Using average VA/m2 rates outlined in Appendix C of AS3000, determine the maximum demand of the 400 Volt three-phase consumer mains for this commercial installation. Type of Occupancy Load Shops Energy Demand Area Average VA/m2 Demand VA Light and power Air conditioning Offices Light and power Air conditioning Total VA Maximum Demand ______________ Amps per phase __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ 6077AC MY2011 TAFE NSW - 12 - SECTION C – (Cont’d) QUESTION 2. (5 Marks) Calculate the maximum demand of a three-phase 230/400V sub-main to a non-airconditioned portion of a factory having the following load: 48 only triple 36 W fluorescent luminaires having a rating of 0.45 A each (3 circuits) 18 only 10 A double socket outlets (3 circuits) 2 only 3-phase 400 volt motor having full load current of 20 A per phase 2 only 3-phase 400 volt motors having full load current of 10 A per phase each Load group Load description Qty Calculation Demand Demand Demand (Red) (White) (Blue) Lighting Socket outlets 400V - 20A motor 400V - 20A motor 400V - 10A motor 400V - 10A motor Maximum Demand 6077AC MY2011 TAFE NSW - 13 - SECTION C – (Cont’d) QUESTION 3. (5 Marks) Calculate the maximum demand of a three-phase 230/400V consumer main to a block of 21 town houses (units) each having following load: 28 only lighting points 6 only single socket outlets 16 only double socket outlets 6.9 kW 230V electric cook top 4.6 kW 230V electric oven 8 kW permanently connected air conditioner having full-load current of 16 A 4.6 kW 230V storage hot water service Balance the load evenly over the three-phases. Load group Load description Qty Calculation Demand (Red) Demand (White) Demand (Blue) Lighting Socket outlets Electric cooktop Electric oven Air conditioner Hot water service Maximum Demand 6077AC MY2011 TAFE NSW - 14 - SECTION C – (Cont’d) QUESTION 4. (4 Marks) A 400-volt, three-phase final sub-circuit in a non-domestic installation consists of three X90, single-core, thermoplastic and sheathed copper conductors supplying a 100-ampere resistive load. The circuit is enclosed in heavy-duty rigid thermoplastic conduit with no other circuits. The conduit is buried in the ground having an ambient soil temperature of 25ºC and has a top cover of 0.5 metre. Circuit protection is by way of HRC fuses and the distance from the switchboard to the load terminals of the equipment is 70 metres. Calculate the minimum permissible cable size if the voltage drop in this cable segment is not to exceed 2.5%. Voltage Drop Table No: ____________________________________ Conductor size: ____________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ _________________________________________________________________________ 6077AC MY2011 TAFE NSW - 15 - SECTION C – (Cont’d) QUESTION 5. (7 Marks) Calculate the voltage drop in each segment of a three-phase, 400-volt non-domestic installation consisting of the following: (a) Consumer main: Phases: Maximum demand: Route length: Cable size: Cable configuration: Cable installation: 3 63 A 40 m 25 mm2 X90 single core thermoplastic and sheathed copper conductors The circuit is enclosed in heavy-duty rigid thermoplastic conduit with no other circuits. Conduit is buried in the ground having an ambient soil temperature of 25ºC and has a top cover of 0.5 m Voltage Drop Table No: ____________________________________ mV/A.m rating: ____________________________________ Volt drop: ____________________________________ ____________________________________ (b) Sub-main: Phases: Maximum demand: Route length: Cable size: Cable configuration: Cable installation: 6077AC MY2011 3 40 A 30 m 16 mm2 V90 single core thermoplastic and sheathed copper conductors The cables are clipped to the building structure in trefoil formation and installed in single circuit configuration, unenclosed in air Voltage Drop Table No: ____________________________________ mV/A.m rating: ____________________________________ Volt drop: ____________________________________ TAFE NSW - 16 - SECTION C – (Cont’d) QUESTION 5. (c) (cont) Final sub-circuit: Phases: Maximum demand: Route length: Cable size: Cable configuration: Cable installation: 1 20 A 25 m 2.5 mm2 V90 two-core and earth thermoplastic and sheathed copper conductors The cables are clipped to the building structure and installed in single circuit configuration, unenclosed in air Voltage Drop Table No: ________________________________________ mV/A.m rating: ________________________________________ Volt drop: ________________________________________ ________________________________________ Considering all three portions, does the final voltage-drop comply with the requirements of AS/NZS 3000? Provide a reason why it does, or does not comply. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ 6077AC MY2011 TAFE NSW - 17 - SECTION C – (Cont’d) QUESTION 6. (3 Marks) The maximum demand current of a sub-mains in a non-domestic installation is calculated to be 50 amperes. The selected cable is 4-core, non-armoured, X90 insulated and sheathed, circular cable with copper conductors. Installation of the cable places is clipped directly to an internal wall with four other similar circuits, touching in a single layer, open to the air, and protected by 50 Amp circuit breakers. Use AS/NZS 3008.1.1 to determine a suitable conductor size for the installation. Multiple Circuits: De-rating Table No: Column No: De-rating factor: Minimum Current Carrying Capacity of the required conductor: Required conductor size: Table No: 3( ) Item No: Table No: Column No: Conductor size: Earth conductor: Minimum earth conductor size: Reference: Coordination between conductors and protective devices – refer to AS3000 Clause 2.5.3.1 IB ( ) ≤ IN ( ) ≤ IZ ( ) Circle Correct Answer Does the selected cable meet the AS3000 : 2007 IB ≤ IN ≤ IZ requirements? 6077AC MY2011 Yes TAFE NSW No - 18 - SECTION C – (Cont’d) QUESTION 7. (3 Marks) Three circuits of four-core V90 circular thermoplastic insulated and sheathed non-armoured copper conductor cables are buried directly in the ground at a depth of 0.5 m where the ambient soil temperature is 25ºC. The cables are spaced at a distance of 150 mm from one another. Each circuit is to carry 100 Amps and protected by 100 Amp circuit breakers. Use AS/NZS 3008.1.1 to determine a suitable conductor size for the installation. Multiple Circuits: De-rating Table No: Column No: De-rating factor: Minimum Current Carrying Capacity of the required conductor: Required conductor size: Table No: 3( ) Item No: Table No: Column No: Conductor size: Earth conductor: Minimum earth conductor size: Reference: Coordination between conductors and protective devices – refer to AS3000 Clause 2.5.3.1 IB ( ) ≤ IN ( ) ≤ IZ ( ) Circle Correct Answer Does the selected cable meet the AS3000 : 2007 IB ≤ IN ≤ IZ requirements? 6077AC MY2011 Yes TAFE NSW No - 19 - SECTION C – (Cont’d) QUESTION 8. (3 Marks) A 230 Volt final sub-circuit consists of a V75 rated multi-core cable and supplies a 25Amp single phase socket outlet within a factory. A 25A type ‘C’ circuit breaker protects the circuit. The active and neutral copper conductors have a cross sectional area of 4mm2. Determine the maximum allowable resistance of the associated 2.5mm2 protective earth conductor, which is to be measured when the supply is unavailable and the ambient temperature is 20°C. __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ __________________________________________________________________________ 6077AC MY2011 TAFE NSW - 20 - SECTION C – (Cont’d) Use the information in Table 1 as required to answer Questions 9 and 10 of this section. Table 1 2 Conductor size — mm 6077AC MY2011 Impedance at 50 Hz in Ω/km at 75°C 2.5 9.01 4 5.61 6 3.75 10 2.23 16 1.40 25 0.892 35 0.649 50 0.484 TAFE NSW - 21 - SECTION C – (Cont’d) QUESTION 9. (4 Marks) The diagram below shows a single line diagram representing a supply transformer, consumer mains to a main switchboard, submain to a distribution board, and a final sub-circuit to an appliance. An earth fault of zero impedance occurs at the appliance. Calculate the total fault loop impedance. ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ 6077AC MY2011 TAFE NSW - 22 - SECTION C – (Cont’d) QUESTION 10. (6 Marks) The supply authority has nominated a Prospective Short-Circuit current rating of 30kA at the point of supply of a 230/400 Volt installation. Given the details provided below, calculate the Prospective Short-Circuit (P.S.C) current rating at the distribution board. (Note: The Prospective Short Circuit current is the maximum current that could flow under short circuit conditions, and is based on a symmetrical three-phase bolted fault). Description Consumer Mains Point of Supply to MSB Submain MSB to Distribution Board Length Cable Type 2 Phases 22 m 50 mm Copper 4 x 1 Core 3 38 m 25 mm2 Copper 4 x 1 Core + 6 mm2 Copper Earth. 3 ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ ___________________________________________________________ 6077AC MY2011 TAFE NSW - 23 - SECTION D – (15 Marks) INSTRUCTIONS: Answer the following questions in the spaces provided. Figure 1 shows the time-current characteristic curves for type ‘C’ and type ‘D’ thermalmagnetic circuit breakers of a particular manufacturer. Use this information to answer question 1 of this section. (END OF SECTION B) I/I N Figure 1 Multiple of rated current QUESTION 1. (2 Marks) A circuit is to be protected by a 50 Amp type ‘C’ circuit breaker. Using the circuit breaker characteristic curve of Figure 1, determine the approximate minimum and maximum operating times for a fault current of 200 Amps. Minimum _____________ seconds Maximum _____________ seconds 6077AC MY2011 TAFE NSW - 24 - SECTION D – (Cont’d) INSTRUCTION: The questions in this section require some simple drawing. Ensure that the drawing is neat and legible. The use of pencil on the drawings is acceptable for questions 3 and 4 in this section only. QUESTION 2. (4 Marks) The following diagram represents the main switchboard of a domestic installation. For simplification, only a small selection of equipment has been shown. The unprotected consumer mains entering the main switchboard consist of 16 mm2 active and neutral conductors. The consumer mains are single insulated within the metallic enclosure. On the following diagram, neatly draw in all necessary earthing and equipotential bonding conductors required to complete an M.E.N system of earthing. The incoming water service is electrically continuous between the building interior and the ground. Based on the given information, determine the minimum size of all earthing conductors, which is to be shown alongside each conductor (active and neutral conductors need not be shown). 6077AC MY2011 TAFE NSW - 25 - SECTION D – (Cont’d) QUESTION 3. (6 Marks) The following diagram represents selected items contained within a domestic electrical distribution board. Neatly draw in all active and neutral conductors necessary for the safe and proper operation of the circuits. Earth conductors need not be shown. Power circuits P1 and P2 will be individually protected by their own 16A MCB’s. Light circuits L1 and L2 will be individually protected by their own 16A MCB’s. Power Circuit P3 is to be protected by a 16A combination RCD/MCB. All circuits are to be RCD protected. 6077AC MY2011 TAFE NSW - 26 - SECTION D – (Cont’d) QUESTION 4. (3 Marks) Using the arrangement shown in figure 1, show the connections/disconnections required to carry out an insulation resistance test on the entire installation. Correctly marked drawing = 1 marks Place an X against conductors to indicate disconnection. Show connections to meter and bridging connections if required. 1 mark deducted for each incorrect answer or omission. a) What range would the insulation resistance tester have to be set to? _________________________ b) What position, on or off, would the main switch have to be in? _________________________ c) (1 Mark) (0.5 Mark) What position, on or off, would each of the final sub-circuit circuit breakers have to be in? _________________________ 6077AC MY2011 (0.5 Mark) TAFE NSW - 27 Family Name ................................................................................. Given Name ................................................................................... Student Number ........................................................................... Centre ............................................................................................ Signature ....................................................................................... ANSWER SHEET – Section A (Multi-choice Questions) Module - 6077AC Examination Date: 23 June 2011 Instructions: • Enter your name and college on this sheet. • Place an X in box of your choice. If you make a mistake- circle your answer choose again. • For your convenience you can remove this page while you answer Section A. Remember to re-attach it to the paper when you hand it in. Question 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 a b c X and d Totals Total Correct Section A Total Marks Section A: ………… /20 END OF EXAMINATION 6077AC MY2011 TAFE NSW - 28 - Note: The symbols used on this sheet follow AS1046 pt 1. There are alternate recognised symbols in use. The list does not contain every equation used in the course. Transposition of equations will be necessary to solve problems s t Q = It v= F = ma W = Fs W = Pt η% = P = VI P = I 2R W = mgh output 100 × input 1 Rh = Rc (1 + α∆t ) RT = R1 + R2 + R3 VT = V1 + V2 + V3 I T = I1 + I 2 + I 3 V2 = VT RA R RB 1 1 1 1 = + + CT C1 C2 C3 C= Rx = Fm S S= e = Blv L= V =L ∆I ∆t τ= t= Fm l l µo µ r A µo µ r AN 2 l L R Eg = T = Fr 1 f f = V2 R ρl R= A 1 1 1 1 = + + RT R1 R2 R3 R1 I 2 = IT R1 + R2 τ = RC CT = C1 + C2 + C3 H= Φ= R2 R1 + R2 Q V Fm = IN V R I= P= R1 A1l2 A2l1 R2 = ∆v t a= C= Aε oε r d B= Φ A ∆Φ ∆t ∆Φ L=N ∆I V =N F = Bil ΦZnP 60a np 120 P= 2πnT 60 V = 0.707Vmax I = 0.707 I max Vave = 0.637Vmax I ave = 0.637 I max v = Vmax sin φ i = I max sin φ I= X L = 2πfL XC = Z = R2 + (X L − X C ) 2 6077AC MY2011 V Z 1 2πfC TAFE NSW - 29 cos φ = P S cos φ = R Z S = P2 + Q2 P = VI cos φ Q = VI sin φ VL = 3VP I L = 3I P S = 3VL I L P = 3VL I L cos φ Q = 3VL I L sin φ W − W1 tan φ = 3 2 W2 + W1 Q = mC∆t V ' = 4.44ΦfN V1 N1 = V2 N 2 S = VI fo = 1 2π LC N syn = 120 f p Vreg % = s% = (VNL − VFL ) × 100 VFL 1 I ST = × I DOL 3 2 V TST = ST × TDOL V E= Φv A 1 (n I 2 N1 = I1 N 2 − n ) 100 × 1 nsyn syn Vreg % = (VNL − VFL ) × 100 VNL 1 TST = × TDOL 3 I motor st = E= %TAP × I DOL 100 I d2 1 fr = s% × f 100 T= ΦZIP 2πa I ST = VST × I DOL V 2 %TAP I line st = × I DOL 100 ηv = Φv P VL = 0.45Vac VL = 0.9Vac VL = 1.17V phase VL = 1.35Vline PRV = 2Vac PRV = 2 2Vac PRV = 2.45Vac Vripple = 2Vac Vripple = 0.707V phase Vripple = 0.1895Vline 6077AC MY2011 TAFE NSW
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