EE533D1_01Oct2010

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CLASS EE 533D1 : 

OVERVIEW ON: CONDUCTORS SIZES, TYPES, AND AMPACITIES CLASS EE 533D1 Engr. ARTURO M. ZABALA, PEE 04 October 2010 Audio Visual Room, Technological Institute of the Philippines - Manila

- Conductor Sizes- Characteristics of Conductors- Kinds of Wires and Cables- Ampacity of Conductors- Factors in Determining the Resistance of a Length of Wire- Principal Determinant of Conductor Operating Temperature - Factors in Derating Conductor Ampacities (Ampacity Adjustments) : 

- Conductor Sizes- Characteristics of Conductors- Kinds of Wires and Cables- Ampacity of Conductors- Factors in Determining the Resistance of a Length of Wire- Principal Determinant of Conductor Operating Temperature - Factors in Derating Conductor Ampacities (Ampacity Adjustments) PRESENTATION OUTLINE

WHAT IS A CONDUCTOR? : 

WHAT IS A CONDUCTOR? Conductors are used to conduct electric power where it is generated to the point where it is used.

GENERAL LIGHTING LOADS BY OCCUPANCY : 

GENERAL LIGHTING LOADS BY OCCUPANCY Use of table 2.20.2.3 General Lighting Loads by Occupancy (page 100)

GENERAL LIGHTING LOADS BY OCCUPANCY : 

GENERAL LIGHTING LOADS BY OCCUPANCY Lighting load (VA) x dimension (m2) = 24 VA x 100 m2 = 2,400 VA 2,400 Amperes = 230 = 10 amperes

GENERAL LIGHTING LOADS BY OCCUPANCY : 

GENERAL LIGHTING LOADS BY OCCUPANCY 10 A No. of circuit/s = 15 A for lighting ckt. = 0.66 or 1 minimum of one (1) lighting branch circuit

GENERAL LIGHTING LOADS BY OCCUPANCY : 

GENERAL LIGHTING LOADS BY OCCUPANCY Important : Most receptacle outlets in residential/dwelling units are considered by the Code to be part of “general illumination”. Appliance receptacle outlets in the kitchen, dining room, laundry, and workshop are not to be considered part of general illumination

CONDUCTOR SIZES : 

CONDUCTOR SIZES STRANDED CONDUCTORS Each strand act as a separate conducting unit Cross-sectional area is determined by adding the individual strands together Greater than in overall diameter than solid wire Number of circular mils is the same

CHARACTERISCTICS OF CONDUCTORS : 

CHARACTERISCTICS OF CONDUCTORS SILVER CONDUCTOR - Better conductor than copper - Used where a delicate and highly conducting material is necessary (brushes in motor and commutator of watthour meters) - Low vapor pressure arcs do not readily form when the circuit is opened - Use limitedly as conductor because of its cost

CHARACTERISCTICS OF CONDUCTORS : 

CHARACTERISCTICS OF CONDUCTORS COPPER CONDUCTOR - Used more extensively as conductor - High conductivity - Moderate cost - Ductility - High tensile strength - Not easily abraded - Not corroded by atmosphere - Readily soldered

CHARACTERISCTICS OF CONDUCTORS : 

CHARACTERISCTICS OF CONDUCTORS ALUMINUM CONDUCTOR - Has 61% of the conductivity of copper - Twice the conductance of copper (for the same length and weight) - Greater carrying-capacity that of copper - Greater heat dissipating surface - Softer than copper - Less tensile strength - Not easily abraded - Not affected by exposure to the atmosphere - Cannot easily soldered - Used as conductor for high voltage transmission (lightness and large diameter are an advantage)

CHARACTERISCTICS OF CONDUCTORS : 

CHARACTERISCTICS OF CONDUCTORS COPPER CLAD ALUMINUM CONDUCTOR - Are drawn from a copper-clad aluminum rod with the copper metallurgically bonded to an aluminum core -The copper form a minimum of 10% of the cross-sectional area of a solid conductor or each stand of a stranded conductor

KINDS OF WIRES AND CABLES : 

KINDS OF WIRES AND CABLES SIX (6) MAJOR CATEGORIES OF ELECTRIC WIRES AND CABLES BEING PRODUCED LOCALLY Building Wires Are standard wires used in residential, commercial, and industrial buildings Communication Cables Telephone cables, switchboard cables, and coaxial cables used in telecommunications Magnet Wires Utilized for electric motor coils, ballast and x’formers

KINDS OF WIRES AND CABLES : 

KINDS OF WIRES AND CABLES Power Cables Are standard wires used in residential, commercial, and industrial buildings Special Cables Telephone cables, switchboard cables, and coaxial cables used in telecommunications Aluminum Wires and Cables Utilized for electric motor coils, ballast and x’formers

CLASSIFICATION OF POWER CABLES : 

CLASSIFICATION OF POWER CABLES LOW VOLTAGE up to 2,000 volts (2 kV) MEDIUM VOLTAGE 2,001 to 35,000 volts HIGH VOLTAGE 35,001 to 150,000 volts VERY HIGH VOLTAGE 150,001 to 750,000 volts

CONDUCTOR UNIT AREA AND RESISTANCE : 

CONDUCTOR UNIT AREA AND RESISTANCE CIRCULAR MIL mil = 1 / 1 000 in = .001 in Area of square mil = 0.000001 in2 Area of circular mil = 0.7854 x 10-6 in2

CONDUCTOR UNIT AREA AND RESISTANCE : 

CONDUCTOR UNIT AREA AND RESISTANCE Square mil = circular mils x 0.7854 = circular mil / 1.273 Circular mil = square mils / 7854 = square mils x 1.273 = D2 in mils

CONDUCTOR UNIT AREA AND RESISTANCE : 

CONDUCTOR UNIT AREA AND RESISTANCE

WHAT IS AMPACITY? : 

WHAT IS AMPACITY? Ampacity is the current in amperes a conductor can carry continuously under the conditions of use without exceeding its temperature rating. The ampacity of the conductor is chosen from the proper ampacity which be adequate to carry maximum load current (p. 350, PEC 2009) The ampacity is also determined after applying all the temperature correction and derating factors (p. 347, PEC 2009)

FACTORS IN DETERMINING THE RESISTANCE OF A LENGTH OF WIRE : 

FACTORS IN DETERMINING THE RESISTANCE OF A LENGTH OF WIRE THE MATERIAL OF WHICH THE WIRE IS MADE - Different types of material have different wire resistance THE DIAMETER OF THE CONDUCTOR - The larger the diameter, less resistance it will have THE TEMPERATURE OF THE CONDUCTOR - Most conductive materials will increase resistance with an increase of temperature (except carbon, silicon, and germanium.

PRINCIPAL DETERMINANT OF CONDUCTOR OPERATING TEMPERATURE : 

PRINCIPAL DETERMINANT OF CONDUCTOR OPERATING TEMPERATURE The temperature rating of the conductor is the maximum temperature at any location along its length, that the conductor can withstand over a prolonged time period without serious degradation

PRINCIPAL DETERMINANT OF CONDUCTOR OPERATING TEMPERATURE : 

PRINCIPAL DETERMINANT OF CONDUCTOR OPERATING TEMPERATURE AMBIENT TEMPERATURE - Ambient temperature may vary along the conductor length as well as from time to time HEAT GENERATED - Heat generated internally in the conductor as the result of load current flow THE RATE WHICH GENERATED HEAT DISSIPATES IN THE AMBIENT MEDIUM - Thermal insulation which cover or surrounds will affect the rate of heat dissipation

PRINCIPAL DETERMINANT OF CONDUCTOR OPERATING TEMPERATURE : 

PRINCIPAL DETERMINANT OF CONDUCTOR OPERATING TEMPERATURE ADJACENT LOAD CARRYING CONDUCTOR - Adjacent conductors have the dual affect of raising the ambient temperature and impending heat dissipation

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) DUE TO HIGH TEMPERATURES - When conductors are installed in locations where the ambient or surrounding temperature is higher than 30 ˚C.

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Example 1 : If PAGASA lists the average summer temperature as 35 ˚C, determine the new corrected ampacity of the conductor and the properly sized conductor capable of carrying the load current when a 100 mm2 THWN copper conductor are to be installed in the said ambient temperature. Given : Average summer temperature = 35 ˚C Size of conductor = 100 mm2 THWN copper

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Required : Determine the new corrected ampacity of the conductor and the sized conductor capable of carrying the load.

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Solution : From table 3.10.1.16, p. 350 : 100 mm2 THWN = 220 amperes Ambient temperature Correction factor for 35 ˚C = 0.94 Therefore, 220 A x 0.94 = 206.80 A

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Example 2 : What is the correct ampacity for a 30 mm2 THHN copper conductor when there are six (6) current carrying conductor in the circuit? Given : Size of conductor = 30 mm2 THHN copper Number of conductors = six (6) Required : Determine the new corrected ampacity of the conductor and the properly sized conductor capable of carrying the load

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Solution : From table 3.10.1.16, p. 350 : 30 mm2 THHN = 115 amperes From table 3.10.1.16, p. 347 : Number of current carrying conductors = 6 Adjustment factor = 80% Therefore, 115 A x 0.80 = 92 A

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Example 3 : Four (4) current carrying 80 mm2 TW copper conductors are to be installed in a raceway in an ambient temperature of 33 ˚C. Determine the new corrected ampacity of the conductor and the properly size conductor capable of carrying the load current safely. Given : Size of conductor = 80 mm2 TW copper Number of conductors = four (4)

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Required : Determine the new corrected ampacity of the conductor and the properly sized conductor capable of carrying the load

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Solution : From table 3.10.1.16, p. 350 : 80 mm2 THHN = 160 amperes Ambient temperature Correction factor for 33 ˚C = 0.91 From the given above values, 160 A x 0.91 = 145.6 A

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Solution : From table 3.10.1.16, p. 350 : 80 mm2 THHN = 160 amperes Also, the no. of current carrying conductor = 4 Adjustment factor = 80% Then, 145.6 A x 0.80 = 116.48 A

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Answer in no. 1: Applying ambient temperature factor From 220 A to 206.80 A Answer in no. 2: Applying derating factor due to number of current carrying conductors From 115 A to 92 A Answer in no. 3: Applying all the factors, From 160 to 145.6 to 116.48 A

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Important note : This derated ampacity value is not permitted to be smaller than the circuit load current of the circuit. If it is smaller than the circuit load current, then it will be necessary to choose a larger wire and repeat the calculations.

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) With the given example, the new corrected conductor ampacity is smaller than the load current. Formula : Table load current ampacity = _______________________________________ derating factor x temp. correction factor

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Formula : Table load current ampacity = _______________________________________ derating factor x temp. correction factor Answer in no. 1: Applying ambient temperature factor Table ampacity = 220 / 0.94 = 234 A

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Formula : Table load current ampacity = _______________________________________ derating factor x temp. correction factor Answer in no. 2: Applying derating factor Table ampacity = 115 / 0.80 = 143 A

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) : 

FACTORS IN DERATING CONDUCTOR AMPACITY (Ampacity Adjustments) Answer in no. 3: Applying temperature correction and derating factors. Table load current Ampacity = _______________________________________ derating factor x temp. correction factor = 160 0.91 x 0.80 = 219 amperes Finally, a 150 mm2 TW copper conductor is capable of carrying 160 amperes when temperature correction and derating factors were applied

Slide 40: 

FINAL PERIOD EXAMINATION SCHEDULE October 11, 2010 (Monday) : Quiz Coverage : Design reference material and essay. October 15, 2010 (Friday) : Exam Coverage : Design reference material and Oct. 8 (lecture)

Slide 41: 

End of Presentation THANK YOU...

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