Load Distribution on Circuit Breaker - Research Paper Example

Load Distribution Name of the student Name of the institution Date of Submission Table of Contents Table of Contents 2 Executive summary 3 1.0Produce a Load Distribution Schedule for the ground floor and the first floor 3 2.0 Details of the MCB selection Procedure 5 3.0 Consider two main distribution boards (GF and FF) 3.1 The main circuit breakers for both level 6 4.0 Consider the case of improving the power factor for villa design  10 5.0 Calculation of the cable size for the villa 12 BIBLIOGRAPHY 18 Executive summary This paper explains Load distribution in Villa construction. The paper begins by producing Load distribution of the ground and first floor followed by MCB selection criteria before giving circuit main breaker for the Villa. The paper gives explanation of improving power within the villa and details calculation of cable size used in the Villa. 1.0 Produce a Load Distribution Schedule for the ground floor and the first floor The first floor distribution schedule of the Villa is given in the figure below. It gives ELCB settings, Ratings, SL No, Circuit number in the first flow, MCB Ratings, Circuit Wire size, Cable length and ECC wire size. Load Distribution Schedule ELCB Setting (mA) ELCB Rating(A) SL No. Circuit No. MCB Rating in A Circuit Wire Size mm2 ECC Wire Size mm2 Cable Length m Cable Type Room/Area 200 40 1 R1 8 1.1 1.1 3 Times Microwave LMR-flexible cable Lightning-WC 200 40 2 Y1 8 1.1 1.1 4 Times Microwave LMR-flexible cable Lightning-Hall 200 40 3 B1 8 1.1 1.1 3 Times Microwave LMR-flexible cable Lightning-Dining Hall 300 60 4 R2 12 1.1 1.1 15 Times Microwave LMR-flexible cable Dining Hall-Electric cooker 200 40 5 Y2 8 1.1 1.1 3 Times Microwave LMR-flexible cable Lightning-Lounge 300 30 6 B2 12 1.1 1.1 16 Times Microwave LMR-flexible cable Lounge-Electric appliances 200 40 7 R3 8 1.1 1.1 5 Times Microwave LMR-flexible cable Lightning-Bedroom 1 200 40 8 Y3 8 1.1 1.1 5 Times Microwave LMR-flexible cable Lightning-Bedroom 2 200 40 9 B3 8 1.1 1.1 6 Times Microwave LMR-flexible cable Lightning-Bedroom 3 200 40 10 R4 8 1.1 1.1 5 Times Microwave LMR-flexible cable Lightning-Bathroom 200 40 11 Y4 8 1.1 1.1 4 Times Microwave LMR-flexible cable Lightning-Landing 2.0 Details of the MCB selection Procedure According to Niesłony & Kurek (2012), miniature Circuit Breaker (MCB) is a device that is responsible for switching of the electrical circuit upon detection of an electric fault or during overload.Therefore, the one used in my installation process was Type B, which trips three to five full load current. It had 5KA fault level. For Villa case study, the diagram is the one used in breaking circuit in case of electrical default. The diagram below shows the details of the MCB used in my installation Figure 1 Electro-magnetic protection This is the trip unit that opens up the breaker contacts whenever a fault condition is detected since it is current sensitive. The device is also incorporated with thermal trip unit which protects against overload and is used in the Villa. The thermal unit has a bimetallic element located at the back of the trip bar and is part of the current’s flowing path. The magnetic trip unit protects the electric circuit against shorter circuit during current flow. Whenever there is a short circuit, there is passage of high magnitude via the coils resulting to generation of a magnetic field that eventually attracts the movable armature closer to the fixed armature. In the process, a hammer is pushed against the contact that is movable hence opening up the breaker contacts. The opening up of the breaker contacts in the event of a shorter circuit takes very few seconds to complete (Mohseni & Kang, 2014). The diagram below shows the finer components of the magnetic trip unit Figure 2 3.0 Consider two main distribution boards (GF and FF) 3.1 The main circuit breakers for both level Distribution board is an assemblage of parts that is compost fuses or circuit breakers combined together to enable supply of electric energy to final circuit or through other distribution boars. It includes:- Single phase distribution board: A single phase distribution board normally contains sections, that is, Double Pole MCB (Main switch), Single Pole MCB (Circuit Breakers and Fuses) and Residual Current Devices RCD Double Pole MCB (Main switch): This is a device that enables turning on and off of the electricity supply to the first floor rooms since it is the main gadget responsible for controlling the entire electric supply. It is always advisable to turn the main switch off during situations such as fire outbreak in the house, during electric installation in the house, this is one of the precautionary measures in Villa. Single Pole MCB (Circuit Breakers and Fuses): This is a device responsible for switching on and off of the electric supply system normal or even abnormal situations. They are often automated protective services in the parent switch board or the fuse box. Residual Current Devices (RCD): According to Li & Chen (2012), the Residual Current Device is an electric device responsible for turns off the electric supply upon detecting that the electric supply current is in a state of imbalance between the energized conductors and the return neutral conductors hence eventually disconnecting the electric supply. We worked with the assumption that we will connect the three phase electric installation with only a single phase load unit. In a three phase, once the three-phase energy meter is connected, the Moulded Case Circuit Breaker (MCCB) is then connected to the incoming three (R, Y, B) from a three phase energy meter (Papadopoulos et al., 2013). Finally, the neutral wires will be connected to the Residual Current Devices (RCDs) then neutral links and finally to the specific loads. The diagram below shows an example of a three phase distribution board An Earth Leakage Circuit Breaker (ELCB) is a device that is used purposefully in detecting current leakages to the earth after an installation has been done. There are types of ELCBs Current Earth Leakage Circuit Breaker (Current-ECLB) It is also known as Residual Current Device (RDC), it involves connecting supply and return circuit conductors with the sensing coil. Therefore, in the event that magnetic field fails to cancel current, the RCD will detect the disproportion and thus trip the contact (Duensing, 2015). The search coil, neutral coil and phase oil are normally curled on one transformer. The current always passes through supply coil, the load and return back via the neutral coil. The neutral coil and the phase coil are curled in order to emit opposing magnetic flux. Whenever current passes via both the coils, the magnetic impact will be eliminated under the healthy circuit condition (Duensing, 2015). Whenever there is a leakage to earth in the in the load circuit or in between the load circuit and the connection of the RCB circuit, the current flowing back through neutral coil will be able to be reduced.in the event that the magnetic flux inside the main transformer is disproportional, the sum of the magnetic flux from the other direction will hence not be zero. The difference of the magnetic flux will therefore be known as a residual flux (Duensing, 2015). The changing residual flux in the main transformer normally crosses the route with the curled search coil, resulting to production of the electromotive force (e.m.f) through the search coil. The electromotive force is also known as alternating voltage. The alternating voltage produces current inside the wiring of the trip circuit. The trip current of the circuit breaker is therefore controlled by this current. The residual magnetic flux is the one responsible for controlling the trip current between neutral and phase coils (Duensing, 2015). The RCDs is divided into different categories based on their sensitivity values which includes; High sensitivity (HS): these are meant for direct contact connections, they range from 6-10-30 mA Medium sensitivity (MS): these are utilized in areas involving moderate connections; the range is from 100-300-500-1000 mA Low sensitivity (LS): mostly applicable in machineries, range as from 3-10-30 A . Voltage Earth Leakage Circuit Breaker It has a relay coil that is normally connected to the metallic load body at the one end while the other end is connected to the ground wire at the other end. It responsible for detecting currents that are at fault from live wire to the earth wire in the installation circuit it protects. In the event that appropriate voltage is detected via the sense coil in the ELCB, it will automatically put out the power hence remaining off till switch on again. However, a connection from the live wire to any other earthed body is not always detected by this device (Papadopoulos et al., 2013). However, these devices are rarely used today due to the fact that whenever a fault is detected, they end up disconnecting the supply. 4.0 Consider the case of improving the power factor for villa design  Power factor basically refers to the relationship between the power utilized by us and the ability to generate and supply this power to every household that needs it. Also known as the working power and is normally expressed in kilowatts, the total consumption required is often articulated in kilovolt-amperes (Papadopoulos et al., 2013). Therefore, power factor is the ratio of the working power to the total capability required to generate and supply this power to people. In most circumstances, when the power is low, it intends to have negative impact on the lifespan of electrical appliances due to the fact that the excess heat in the electric supply system is brought about by a factor comparable to the square of the current increase especially during nonlinear system load. Therefore, electricity regulatory board tend to impose restrictions to electricity consumers and thus surcharging them whenever their power factor is less than 0.85 (Papadopoulos et al., 2013). The electricity regulatory body stated that observing correct power factor results to savings in the amount spent in energy bills. Logically, the power factor is known as the cosine of the phase difference between the current flow and source voltages, that is, the fraction of the total power also known as apparent power consumed while performing a given work Cos φ= (Active power/Apparent Power) According to Papadopoulos et al. (2013), in transferring a given amount of power at a certain voltage level, the electrical current tend to be inversely proportional to the cos φ proving the fact that when the power factor is more, the amount of current flowing will be lower. When the current flow is low, a small cross sectional surface area of the conductors will be utilized hence saving on the conductors and amount of money spent in electricity. Therefore, having a low power factor improves the flow of current in conductors thus lowering the copper loss level. In addition, KVA rating of machines is in turn reduced whenever the power factor is high, KVA=KW/ Cos φ So it is always preferable to maintain the electrical power factor close to unity. Ways of improving power factor includes: Phase advancer: This is a device basically used to enhance the power factors of the induction motors. They are normally fixed on the edge of the motor and connected in the motor’s rotor circuit. It generates a designated amount of amperes thus producing the desired amount of flux at a slip frequency which in turn improves the power factor. Otherwise, in case the ampere turns are increased, it can be made to operate at the foremost power factor. Capacitors’ usage: Based on the fact that loads are inductive in nature, they function properly given the amount of reactive power. The bank of capacitors installed parallel to the load is responsible for provision of the reactive power. The capacitors being the source of local reactive power, they permit less reactive power flows through the pathway and hence minimizing the phase difference between the current and the voltage. 5.0 Calculation of the cable size for the villa The calculation of the cable size follows the steps below: Step 1 Gather sufficient data about the cable, the conditions required for installation to take place as well as the amount of load it will eventually carry, for instance, in my case the load details had Load type was motor, three phase for the ground floor and single phase for the first floor, starting power factor (pu), load starting current (A) and system/source voltage (Niesłony & Kurek, 2012). Step 2 Cable selection in respect to the current rating; whenever the current flows through the cable, it produces heat through the resistive losses in the conductors , dielectric losses based on the insulation as well as resistive losses based on the current flowing through any cable screens (Niesłony & Kurek, 2012). Formulae Installed current rating Ic=Ib.kd Ic is the installed current rating (A) Ib is the base current rating (A) kd are the product of all the derating factors  Determine the minimum cable size based on voltage drop considerations; a cable’s conductor is normally seen as impedance hence whenever there is a flow of current, there will be a voltage drop across it (Niesłony & Kurek, 2012). Formulae Three Phase voltage drop (V3Ø) /(3I(RC Cos Ø+ XC Sin Ø)L 1000 I is the nominal full (A) RC is the ac resistance of the cable (Ω/km) XC is the ac reactance of the cable (Ω/km) Cos Ø is the load power factor (pu) L is the length of the cable From the calculation {3*5(2* cos 43*+ 5 Sin 30)4}1000 = 15(1.463 + 2.5)4/1000 = 0.23778 Single Phase voltage drop (V1Ø) /(2I(RC Cos Ø+ XC Sin Ø)L 1000 Calculating Maximum Cable Length due to Voltage Drop Three Phase voltage drop (V3Ø) Lmax= 1000V3ø /(3I(RC Cos Ø+ XC Sin Ø)L Single Phase voltage drop (V1Ø) Lmax= 1000V1ø /(2I(RC Cos Ø+ XC Sin Ø)L = 1000/[2*5 (2 cos 43 + 5sin 30)/4] = 1000/ 10*3.963/4 = 1000/9.906 = 100.95 Determine the minimum cable size based on short circuit temperature rise; when the circuit is small, a large amount of current tend to flow through the cable at a short period of time while causing temperature rise in the process. However, high temperature may result to undesired reactions in the cable insulation, casing materials and other components as well which would prematurely degrade the condition of the cable. Therefore, the size of the cable should be taken into consideration to ensure it withstands the largest short circuit involved therein (Niesłony & Kurek, 2012). A= /i2t k A minimum cross-sectional area of the cable (mm2) i is prospective short circuit current (A) t is the duration of the short circuit (s) k is the short circuit temperature rise constant A = (72* 3)/80 = 1.84  Determine the minimum cable size based on earth fault loop impedance; It is advisable to consider the earth fault loop impedance of a circuit while sizing the cable, that is, in the event of an earth fault, the upstream protective device ought to act to interrupt the fault within the maximum disconnection time so as to protect from any inadvertent contact (Niesłony & Kurek, 2012). Lmax= 1000V0 IA/(RC + Re)2+ (XC +Xe)2 Lmax is the maximum length of the cable (m) V0 is the phase to earth’s voltage at protective device (V) IA is the earth fault current required to trip the protective device (A) RC and Re are the ac resistances of the active and earth conductors respectively (Ω/km) XC and Xe are the reactance of the active and earth conductors respectively (Ω/km) = 1000/210.9 = 4.74 mm Therefore, once the size has been calculated using the methods above, the cable with the highest size will be chosen. Villa drawings BIBLIOGRAPHY Diaz-Aguiló, M., Sandraz, J., Macwan, R., de León, F., Czarkowski, D., Comack, C., & Wang, D. (2013). Field-validated load model for the analysis of CVR in distribution secondary networks: Energy conservation. Power Delivery, IEEE Transactions on, 28(4), 2428-2436. Niesłony, A., & Kurek, A. (2012). Influence of the Selected Fatigue Characteristics of the Material on Calculated Fatigue Life under Variable Amplitude Loading. Applied Mechanics and Materials, 104, 197-205. Mohseni, I., Rashid, A. K. A., & Kang, J. (2014). Effect of intermediate diaphragm on lateral load distribution factor of multicell box-girder bridges.KSCE Journal of Civil Engineering, 18(7), 2128-2137. Pabla, A. S. (2012). Electric power distribution. Tata McGraw-Hill Education. Duensing, A. (2015). Targeting ETV1 in Gastrointestinal Stromal Tumors: Tripping the Circuit Breaker in GIST?. Cancer discovery, 5(3), 231-233. Li, Y. C., & Chen, C. L. (2012). A novel single-stage high-power-factor AC-to-DC LED driving circuit with leakage inductance energy recycling. Industrial Electronics, IEEE Transactions on, 59(2), 793-802. Papadopoulos, T. A., Chrysochos, A. I., & Papagiannis, G. K. (2013). Narrowband power line communication: Medium voltage cable modeling and laboratory experimental results. Electric Power Systems Research, 102, 50-60. Read More

The diagram below shows an example of a three phase distribution board An Earth Leakage Circuit Breaker (ELCB) is a device that is used purposefully in detecting current leakages to the earth after an installation has been done. There are types of ELCBs Current Earth Leakage Circuit Breaker (Current-ECLB) It is also known as Residual Current Device (RDC), it involves connecting supply and return circuit conductors with the sensing coil. Therefore, in the event that magnetic field fails to cancel current, the RCD will detect the disproportion and thus trip the contact (Duensing, 2015).

The search coil, neutral coil and phase oil are normally curled on one transformer. The current always passes through supply coil, the load and return back via the neutral coil. The neutral coil and the phase coil are curled in order to emit opposing magnetic flux. Whenever current passes via both the coils, the magnetic impact will be eliminated under the healthy circuit condition (Duensing, 2015). Whenever there is a leakage to earth in the in the load circuit or in between the load circuit and the connection of the RCB circuit, the current flowing back through neutral coil will be able to be reduced.

in the event that the magnetic flux inside the main transformer is disproportional, the sum of the magnetic flux from the other direction will hence not be zero. The difference of the magnetic flux will therefore be known as a residual flux (Duensing, 2015). The changing residual flux in the main transformer normally crosses the route with the curled search coil, resulting to production of the electromotive force (e.m.f) through the search coil. The electromotive force is also known as alternating voltage.

The alternating voltage produces current inside the wiring of the trip circuit. The trip current of the circuit breaker is therefore controlled by this current. The residual magnetic flux is the one responsible for controlling the trip current between neutral and phase coils (Duensing, 2015). The RCDs is divided into different categories based on their sensitivity values which includes; High sensitivity (HS): these are meant for direct contact connections, they range from 6-10-30 mA Medium sensitivity (MS): these are utilized in areas involving moderate connections; the range is from 100-300-500-1000 mA Low sensitivity (LS): mostly applicable in machineries, range as from 3-10-30 A .

Voltage Earth Leakage Circuit Breaker It has a relay coil that is normally connected to the metallic load body at the one end while the other end is connected to the ground wire at the other end. It responsible for detecting currents that are at fault from live wire to the earth wire in the installation circuit it protects. In the event that appropriate voltage is detected via the sense coil in the ELCB, it will automatically put out the power hence remaining off till switch on again. However, a connection from the live wire to any other earthed body is not always detected by this device (Papadopoulos et al., 2013). However, these devices are rarely used today due to the fact that whenever a fault is detected, they end up disconnecting the supply. 4.0 Consider the case of improving the power factor for villa design  Power factor basically refers to the relationship between the power utilized by us and the ability to generate and supply this power to every household that needs it.

Also known as the working power and is normally expressed in kilowatts, the total consumption required is often articulated in kilovolt-amperes (Papadopoulos et al., 2013). Therefore, power factor is the ratio of the working power to the total capability required to generate and supply this power to people. In most circumstances, when the power is low, it intends to have negative impact on the lifespan of electrical appliances due to the fact that the excess heat in the electric supply system is brought about by a factor comparable to the square of the current increase especially during nonlinear system load.

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