Efficient Energy Systems 3315ENG.

Transcription

1 Efficient Energy Systems 3315ENG

2 Topics Power and Energy Energy Auditing Efficient lighting Energy Harvesting Motors and Drives Heating Transportat ion.

3 Resources resource material available on (course content) or directly at sok/ees/index.html

4 Sustainable energy - without all the hot air David J MacKay

5 Assessment Laboratories 30% Energy Audit 10% Final Exam 60%

6 Laboratory work will be graded on the spot and marks will be assigned in proportion to each students ability at Completing any pre-lab work Following the laboratory instructions Setting up and running the equipment Recording and analysing the results Demonstrating understanding of the principles To be eligible to pass the course, students are required to attempt and complete all types of assessment and must demonstrate a reasonable degree of competence in the required learning objectives for each type of assessment. Therefore, to obtain a pass or better grade for the course, the student must: 1) achieve an aggregate mark of at least 50% overall 2) achieve at least 40% for the final examination 3) achieve at least 50% for the laboratory component

7 Introduction to Power and Energy The basic stuff we all need to know [1] Fundamentals of Electrical Engineering and Electronics., Tony R Kuphaldt.

8 Mains voltage The mains voltage in Australia is 240V, Isn t it??? What does that mean? Actually in 2000 the Australian mains was redefined as 230V with tolerance of +10% or -6% (AS 60038). The mains is AC. What does the 230V refer to?

9 Can we calculate the RMS???

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11 AC circuits Simple resistive circuits 230V 50Hz [1]

12 AC circuits Simple resistive circuits 230V 50Hz [1] [1]

13 Simple reactive circuits 230V 50Hz [1]

14 Simple reactive circuits 230V 50Hz [1] [1]

15 Complex circuits 230V 50Hz [1]

16 Complex circuits 230V 50Hz [1] [1]

17 Power How do we define power in AC circuits? [1]

18 230V 50Hz [1] P = true power = I 2 R = W Q = reactive power = I 2 X = S = apparent power = I 2 Z = VAR VA

19 230V 50Hz [1] P = true power = I 2 R = Q = reactive power = I 2 X = S = apparent power = I 2 Z = W VAR VA

20 230V 50Hz [1] P = true power = I 2 R = Q = reactive power = I 2 X = S = apparent power = I 2 Z = W VAR VA

21 The Power triangle is simply a vectorial representation of complex power. Note units

22 Power factor The angle between true power and apparent power is the same as the impedance angle The ratio of true power to apparent power is the cosine of this angle The cosine of the angle is called the Power Factor Power factor = true power/apparent power Power factor = Power factor = cos

23 What does having a power factor of <1 mean???

24 Power factor correction Can we correct circuits with a power factor <1??? Most reactive loads are inductive. One might guess we could correct the power factor by connecting a capacitor to the circuit. 230V 50Hz [1]

25 An easier way to verify outcome 230V 50Hz

26 Measuring Power factor 50 Hz

27 Metering AC voltages can be measured by meters of the moving coil or moving iron type [1] [1] Moving iron meters have non linear scales. Meter movements actually respond to current but may be calibrated in volts.

28 Low values of AC current can be measured with a similar meter movement and usually a shunt resistance. For a 1 ma meter movement with 50 Ohm impedance we could make it measure 50 A by using a shunt of Ohm.

29 Of course voltage and current can be measured by microprocessor by applying the voltage (or shunt voltage) to an A/D converter.

30 Current measurements of high currents can be made using current transformers CTs. File:Leistungsschalter-110KV.jpg V = I/N sec x R Burden resistor (R Ohms) I/N sec

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32 Applications Sensing Overload Current Ground fault detection Metering Analog to Digital Circuits Low Cost 50/60Hz Current Transformers Electrical 20 C ambient Competitive pricing due to high volume production Manufactured in an ISO-9001:2000, TS-16949:2002 and ISO-14001:2004 certified Talema facility Fully RoHS compliant 1000 Electrical Specifications P rimary Current 200A nom., 500A max. Turns Ratio loa Vd olt per Amp Ratio at 200A for 100 ohm Volt per Amp Ratio at 20A for 100 ohm load DC Resistance at 20 C Dielectric Withstanding Voltage (Hi-pot) Case Encapsulant Flammibility Terminals Marking Approximate Weight Tolerance Mechanical Specifications Output Volts vs Input Current For various ohmic loads 1000:1 nomina l V/ A V/ A 11 ohms 4KVrms Polycarbonat e Epoxy Conforms to UL94-VO Pins Ø 1.0mm TALEMA Date Code (W/Y) AC1200, Dot at start pin 150 grams ±0.2mm Storage Temperatur e Load Resistance RL in ohms Environmental Specifications -55 to +130 C I nsulation Resistance 100 megohms min. %RE vs RL at Rated primary current (AC1200) Output Voltage in Volts Infinit 10K 5K 1K K Input Current in Amps Dimensions Sec RMS Exciting Voltage in Volts Percent ratio error in % Typical Excitation Curve (AC1150~AC1200) Sec RMS Exciting Current in ma Ø TALEMA INDIA W/Y AC1200 Ø ±1mm Notes: 1) Unless requested, the terminating resistor and the one-turn primary are not supplied 2) Pin 3: Normally for mechanical support only but will be used on center tapped designs I - Turn Primary 200A mA 2 R L 5W 100 ohms 20V

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35 Clamp meter (Tongmeter)

36 HV CT

37 File:Leistungsschalter-110KV.jpg

38 What happens if a CT has the secondary open circuited?

39 Primary transformers PTs can be used to measure high voltages. In conjunction with CTs an apparent power measurement can be made.

40 Hall effect A hall effect sensor produces a potential perpendicular to the direction of current flow and applied magnetic field in a semiconductor. V H = R H I t B

41 Extremely compact current sensors can be made using this technique. The current through the sensor is normally quite small therefore to make a high current sensor the current to be measured creates the magnetic field.

42 ACS712 Fully Integrated, Hall Effect-Based Linear Current Sensor IC with 2.1 kvrms Isolation and a Low-Resistance Current Conductor Features and Benefits Low-noise analog signal path Device bandwidth is set via the new FILTER pin 5 s output rise time in response to step input current 80 khz bandwidth Total output error 1.5% at T A = 25 C Small footprint, low-profile SOIC8 package 1.2 m internal conductor resistance 2.1 kvrms minimum isolation voltage from pins 1-4 to pins V, single supply operation 66 to 185 mv/a output sensitivity Output voltage proportional to AC or DC currents Factory-trimmed for accuracy Extremely stable output offset voltage Nearly zero magnetic hysteresis Ratiometric output from supply voltage TÜV America Certificate Number: U8V Package: 8 Lead SOIC (suffix LC) Description The Allegro ACS712 provides economical and precise solutions for AC or DC current sensing in industrial, commercial, and communications systems. The device package allows for easy implementation by the customer. Typical applications include motor control, load detection and management, switchmode power supplies, and overcurrent fault protection. The device is not intended for automotive applications. The device consists of a precise, low-offset, linear Hall circuit with a copper conduction path located near the surface of the die. Applied current flowing through this copper conduction path generates a magnetic field which the Hall IC converts into a proportional voltage. Device accuracy is optimized through the close proximity of the magnetic signal to the Hall transducer. A precise, proportional voltage is provided by the low-offset, chopper-stabilized BiCMOS Hall IC, which is programmed for accuracy after packaging. The output of the device has a positive slope (>V IOUT(Q) ) when an increasing current flows through the primary copper conduction path (from pins 1 and 2, to pins 3 and 4), which is the path used for current sampling. The internal resistance of this conductive path is 1.2 m typical, providing low power loss. The thickness of the copper conductor allows survival of Continued on the next page Approximate Scale 1:1 Typical Application I P 1 IP+ 2 IP+ 8 VCC 7 VIOUT ACS IP FILTER 4 IP 5 GND V OUT C F 1 nf +5 V C BYP 0.1 µf

43 Power meters Hall effect power sensor The current through the device is proportional to the applied voltage. A magnetic field is generated proportional to the load current. The hall effect output is proportional to the multiple of voltage and current - thus power. [1]

44 Not only will the output voltage of the Hall effect device be the representation of instantaneous power at any point in time, but it will also be a DC signal! This is because the Hall voltage polarity is dependent upon both the polarity of the magnetic field and the direction of current through the conductor. If both current direction and magnetic field polarity reverses -- as it would every half-cycle of the AC power -- the output voltage polarity will stay the same. If voltage and current in the power circuit are 90 o out of phase (a power factor of zero, meaning no real power delivered to the load), the alternate peaks of Hall device current and magnetic field will never coincide with each other: when one is at its peak, the other will be zero. At those points in time, the Hall output voltage will likewise be zero, being the product (multiplication) of current and magnetic field strength. Between those points in time, the Hall output voltage will fluctuate equally between positive and negative, generating a signal corresponding to the instantaneous absorption and release of power through the reactive load. The net DC output voltage will be zero, indicating zero true power in the circuit. [1]

45 Electromechanical meters How it works - Science and Technology. Marshall Cavendish One coil induces flux proportional to voltage into an aluminium disk. Another induces a 90 degree phase shifted flux proportional to current. The rotational torque is proportional to power. A brake magnet keeps the disk stationary when no power is drawn.

46 1 - Voltage coil - many turns of fine wire encased in plastic, connected in parallel with load. 2 - Current coil - three turns of thick wire, connected in series with load. 3 - Stator - concentrates and confines magnetic field. 4 - Aluminium rotor disc. 5 - rotor brake magnets. 6 - spindle with worm gear. 7 - display dials. Gears turn the rotation into a meter reading.

47 Polyphase circuits [1]

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49 What if we doubled the voltage [1]

50 Split phase [1] [1]

51 3 phase

52 3 phase alternators

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54 Cable colour codes The electrical standard in Australia uses the following colours for flexible power cables. Active Brown (To remember - you end up buried in the brown soil if you touch this one) Neutral Blue Ground Green and yellow Fixed wiring in buildings is usually: Active Neutral Ground Red Black Green and yellow

55 Active (Live) Neutral Ground Sockets are wired with the left pin active or live. (To remember - LEFT IS LIVE IN A SOCKET) Neutral Active (Live) Ground Remember the pins of a 3 pin plug are reversed when viewed from the pin side. It is still LEFT IS LIVE from the back.