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NAPTIN GRADUATE SKILLS NAPTIN GRADUATE SKILLS DEVELOPMENT PROGRAMME, DEVELOPMENT PROGRAMME, ORIENTATION PROGRAMME ORIENTATION PROGRAMME Venue: Regional Training Venue: Regional Training Center, Kainji Center, Kainji Date: Friday, November 29, 2013 Date: Friday, November 29, 2013 Topic: Commercial / Energy Topic: Commercial / Energy Metering Part 1. Metering Part 1. Stephen O. Sowemimo (Trainer). Stephen O. Sowemimo (Trainer). 1 NAPTIN, NAPTIN, Power Trainer with a difference November Power Trainer with a difference November 2013 2013

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  • NAPTIN GRADUATE SKILLS DEVELOPMENT PROGRAMME,ORIENTATION PROGRAMME

    Venue: Regional Training Center, Kainji

    Date: Friday, November 29, 2013

    Topic: Commercial / Energy Metering Part 1.

    Stephen O. Sowemimo (Trainer).

    *NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • ENERGY METER

    What is an Energy Meter?An electricity meter or energy meter is a device that measures the amount of electric energy consumed by a residence, business, industry or an electrically powered device.

    Unit of measurementElectricity meters are typically calibrated in billing units, the most common one is the kilowatt hour [kWh], which is equal to the amount of energy used by a load of one kilowatt over a period of one hour. Periodic readings of electric meters establishes billing cycles and energy used during a cycle.

    *NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • ENERGY METER ContdDemand is normally measured in kilowatts (KW), but averaged over a period, most often a quarter or half hour.Reactive power is measured in "thousands of volt-ampere reactive-hours", (kvarh). By convention, a "lagging" or inductive load, such as a motor, will have positive reactive power. A "leading", or capacitive load, will have negative reactive power]Kilovolt-amperes (KVA) measures all power passed through a distribution network, including reactive and actual. This is equal to the product of root-mean-square volts and amperes.These three types of power -- true, reactive, and apparent -- relate to one another in trigonometric form. We call this the power triangle: (Figure below).

    *NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • POWER TRIANGLE

    *NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • POWERS KW, KVAR, KVA RELATIONSHIP

    Power triangle relating apparent power to true power and reactive power. Using the laws of trigonometry, we can solve for the length of any side (amount of any type of power), given the lengths of the other two sides, or the length of one side and an angle.

    REVIEW: Power dissipated by a load is referred to as true power. It is symbolized by the letter P and is measured in the unit of Watts (W).*

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • POWERS KW, KVAR, KVA RELATIONSHIP Contd.Power merely absorbed and returned in load due to its reactive properties is referred to as reactive power. It is symbolized by the letter Q and is measured in the unit of Volt-Amps-Reactive (VAR).Total power in an AC circuit, both dissipated and absorbed/returned is referred to as apparent power. Apparent power is symbolized by the letter S and is measured in the unit of Volt-Amps (VA).These three types of power are trigonometrically related to one another. In a right triangle, P = adjacent length, Q = opposite length, and S = hypotenuse length. The opposite angle is equal to the circuit's impedance (Z) phase angle.

    *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • POWER FACTOR

    Distortion of the electric current by loads is measured in several ways. Power factor is the ratio of resistive (or real power) to volt-amperes. A capacitive load has a leading power factor, and an inductive load has a lagging power factor. A purely resistive load (such as a filament lamp, heater or kettle) exhibits a power factor of 1. *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • HOW ELECTRICITY METERS OPERATEElectricity meters operate by continuously measuring the instantaneous voltage (volts) and current (amperes) and finding the product of these to give instantaneous electrical power (watts) which is then integrated against time to give energy used (joules, kilowatt-hours etc.). Meters for smaller services (such as small residential customers) can be connected directly in-line between source and customer. For larger loads, more than about 200 ampere of load, current transformers are used, so that the meter can be located other than in line with the service conductors.

    *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • Types of Energy Meter

    These can be broadly categorized into two viz Credit Meter and Prepayment Meter. Credit Meter consumption record is billed after customer has utilized the energy. The customer is expected to settle the bill in arrears (post payment), whereas in case of Prepayment Meter, customer pays for units of electricity before utilizing them (pre payment)Credit meters could be electromechanical or electronics (digital).Prepaid meters are purely electronics and could either be wall mounted or pole mounted.

    *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • ELECTROMECHANICAL METERThe most common type of electricity meter is the electromechanical induction watt-hour meter.The electromechanical induction meter operates by counting the revolutions of an aluminum disc which is made to rotate at a speed proportional to the power. The number of revolutions is thus proportional to the energy usage. The voltage coil consumes a small and relatively constant amount of power, typically around 2 watts which is not registered on the meter. The current coil similarly consumes a small amount of power in proportion to the square of the current flowing through it, typically up to a couple of watts at full load, which is registered on the meter.The metallic disc is acted upon by two coils. One coil is connected in such a way that it produces a magnetic flux in proportion to the voltage and the other produces a magnetic flux in proportion to the current. The field of the voltage coil is delayed by 90 degrees using a lag coil. *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • ELECTROMECHANICAL METER Contd.This produces eddy currents in the disc and the effect is such that a force is exerted on the disc in proportion to the product of the instantaneous current and voltage. A permanent magnet exerts an opposing force proportional to the speed of rotation of the disc. The equilibrium between these two opposing forces results in the disc rotating at a speed proportional to the power being used. The disc drives a register mechanism which integrates the speed of the disc over time by counting revolutions, much like the speedometer in a car, in order to render a measurement of the total energy used over a period of time.

    The type of meter described above is used on a single-phase AC supply. Different phase configurations use additional voltage and current coils.

    *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • PICTURE OF THREE PHASE ELECTROMECHANICAL METER *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • ELECTROMECHANICAL METER Contd.Three-phase electromechanical induction meter, metering 100 A 230/400 V supply is a shown above. Horizontal aluminum rotor disc is visible in center of meter. The aluminum disc is supported by a spindle which has a worm gear which drives the register. The register is a series of dials which record the amount of energy used. The dials may be of the cyclometer type, an odometer-like display that is easy to read where for each dial a single digit is shown through a window in the face of the meter, or of the pointer type where a pointer indicates each digit. With the dial pointer type, adjacent pointers generally rotate in opposite directions due to the gearing mechanism.The amount of energy represented by one revolution of the disc is denoted by the symbol Kh which is given in units of watt-hours per revolution. The value 7.2 is commonly seen. Using the value of Kh , one can determine their power consumption at any given time by timing the disc with a stopwatch. *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • ELECTROMECHANICAL METER Contd.If the time in seconds taken by the disc to complete one revolution is t , then the power in watts is P = 3600 x Kh t For example, if Kh = 7.2, as above, and one revolution took place in 14.4 seconds, the power is 1800 watts. This method can be used to determine the power consumption of household devices by switching them on one by one.Most domestic electricity meters are read manually, whether by a representative of the power company or by the customer. Where the customer reads the meter, the reading may be supplied to the power company by telephone, post or over the internet. The electricity company will normally require a visit by a company representative at least quarterly in order to verify customer-supplied readings and to make a basic safety check of the meter.

    *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • Electronic meters (credit meters)

    Electronic meters display the energy used on an LCD or LED display, and can also transmit readings to remote places. In addition to measuring energy used, electronic meters can also record other parameters of the load and supply such as maximum demand, power factor and reactive power used etc. They can also support time-of-day billing, for example, recording the amount of energy used during on-peak and off-peak hours.

    Remote meter reading is a practical example of telemetry. It saves the cost of a human meter reader and the resulting mistakes, but it also allows more measurements, and remote provisioning. Many smart meters now include a switch to interrupt or restore service.

    *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • PICTURE OF A TYPICAL ELECTRONIC CREDIT METER*

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • Electronic meters (credit meters) Contd.

    Electronic meters now use low-power radio, GSM, GPRS, Bluetooth, IrDA, as well as RS-485 wired link. The meters can now store the entire usage profiles with time stamps and relay them at a click of a button. The demand readings stored with the profiles accurately indicate the load requirements of the customer. This load profile data is processed at the utilities for billing and planning purposes.AMR (Automatic Meter Reading) and RMR (Remote Meter Reading) describe various systems that allow meters to be checked without the need to send a meter reader out. An electronic meter can transmit its readings by telephone line or radio to a central billing office. Automatic meter reading can be done with GSM (Global System for Mobile Communications) modems, one is attached to each meter and the other is placed at the central utility office.

    *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • Basic block diagram of an electronic energy meter

    Solid-state design

    Basic block diagram of an electronic energy meter

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Electronic meters (credit meters) Contd.

    As in the block diagram, the meter has a power supply, a metering engine, a processing and communication engine (i.e. a microcontroller), and other add-on modules such as RTC, LCD display, communication ports/modules and so on.The metering engine is given the voltage and current inputs and has a voltage reference, samplers and quantisers followed by an ADC section to yield the digitised equivalents of all the inputs. These inputs are then processed using a Digital Signal Processor to calculate the various metering parameters such as powers, energies etc.RTC and other add-on modules are attached as slaves to the processing and communication section for various input/output functions. On a modern meter most if not all of this will be implemented inside the microprocessor, such as the Real Time Clock (RTC), LCD controller, temperature sensor, memory and analog to digital converters.

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Prepayment meters

    The standard business model of electricity retailing involves the electricity company billing the customer for the amount of energy used in the previous month or quarter. If the retailer believes that the customer may not pay the bill, a prepayment meter may be installed. Prepayment meters are commonly used for customers considered to be a poor credit risk. This requires the customer to make advance payment before electricity can be used. If the available credit is exhausted then the supply of electricity is cut off by a relay.Here in Nigeria, many of our non-MD customers fall into the category of poor credit risk hence, the recent effort towards getting all non-MD customers metered with prepayment meters.

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Picture of a Typical Prepayment Meter

    A wall mounted, smart card, split prepayment meter

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Pole mounted Prepayment meters

    NAPTIN, Power Trainer with a difference November 2013 *

    However, the problem of some customers tampering with wall mounted prepaid meters, especially by bypass, is posing a great challenge. This has prompted the initiative of producing pole mounted prepaid meters. These are mounted on electric poles out of customers reach. Customers load cables and communication cables are extended from the meters on the poles down to supply intake points. The communication cable is connected to Customer Interface Unit (CIU) for energy loading and monitoring of consumption.

    NAPTIN, Power Trainer with a difference November 2013

  • Picture of a Single Phase Pole Mounted PPM

    A typical pole mounted split single phase prepayment meterNAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Picture of a Three Phase PPM

    A typical wall mounted or pole mounted three phase PPM

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Prepaid Meters Energy Purchase / VendingOne system of energy purchase is the Pay Point network, where rechargeable tokens can be loaded with whatever money the customer has available. Recently smartcards are introduced as much reliable tokens that allows two way data exchange between meter and the utility as we have in Unistar Prepaid Meters.Another system of recharging prepaid meters is by entering a unique, encoded twenty digit number using a keypad. This makes the tokens, essentially a slip of paper, very cheap to produce, like in Conlog Prepaid Meters.

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Maximum Demand (MD) Meters

    When customers load demand is more than 45 KVA that could conveniently be metered with non-MD three phase meter, an MD meter is installed, capacity of which depends on the load magnitude. The meters are in broad categories of:Whole Current, Low Voltage, 415 volts C.T. operated, Low Voltage, 415 volts. C.T and V.T. operated, High Voltage, 11 Kv.C.T. and V.T. operated, High Voltage, 33 Kv.They can be electromechanical or digital. They have facilities for measuring Active Energy, KWH and Apparent Energy, KVA used in billing. Some electromechanical also have portion recording Reactive Energy, KVAR while the electronic type are designed to measure many more parameters.

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Metering Current Transformer

    Current transformers used as part of metering equipment for C.T. operated, Low Voltage Maximum Demand Meter. The fourth neutral cable does not require a current transformer because current cannot flow in this cable without also flowing in one of the three phase cables.

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Location of Maximum Demand Meter

    The location of an electricity meter varies with each installation. Possible locations include on a utility pole serving the property, in a street-side cabinet (meter box) or inside the premises adjacent to the consumer unit / distribution board. Electricity companies may prefer external locations as the meter can be read without gaining access to the premises but external meters may be more prone to vandalism.

    Current transformers permit the meter to be located remotely from the current-carrying conductors. This is common in large installations. For example a substation serving a single large customer may have metering equipment installed in a cabinet, without bringing heavy cables into the cabinet.

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Metering Current Transformer and Voltage Transformer

    Except for 100 Amps Whole Current Maximum Demand meter which is in use in some specialized areas, all Maximum Demand meters are CT operated, for Low Voltage MD and CT / VT operated for High Voltage MD. Because the load current is too high to be fed directly through the meter, current transformer (CT) is used to step the load current down to a maximum of 5A. However, when the stepped down value is fed into the meter, the meter reads it as the real load current value if the meter current ratio is the same as the CT ratio. High voltage MD meters also make use of Voltage Transformer (VT) in addition to CT. The supply/metering voltage is stepped down to 110v. and fed across the meter

    NAPTIN, Power Trainer with a difference November 2013 *

    NAPTIN, Power Trainer with a difference November 2013

  • Multiplying Factor (MF)Multiplying Factor (MF) is the figure by which consumption recorded on a MD meter is multiplied to reflect the actual consumption. This is necessary in a situation whereby CT ratio is not the same as the meter current ratio.MF = CT ratio Meter current ratio For example, if CT ratio = 500/5A and Meter current ratio = 300/5A MF = 500 divided by 300 = 500 x 5 = 5 = 1.67 5 5 5 300 3 In High Voltage MD metering, as much as possible the meter is selected in such a way that its voltage ratio is the same as the metering VT ratio. However, in an event that the two are different, necessary adjustment is made with multiplying factor. *

    NAPTIN, Power Trainer with a difference November 2013

    NAPTIN, Power Trainer with a difference November 2013

  • Multiplying Factor (MF)

    For example, if CT ratio = 100/5A, VT ratio = 11,000/110v. and Meter ratio = 50/5A, 33,000/110v. MF = 100 divided by 50 x 11,000 divided by 33,000 5 5 110 110 = 100 x 5 x 11,000 x 110 = 2 = 0.67 5 50 110 33,000 3KWH is the total units of electricity consumed in a specified period of time, usually one month for billing purpose while KVA is the maximum level of power demand within the same period of time.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Capacity Range of MetersAt distribution level we have credit meters of following capacity range: Single phase non- MD 230 volts Three phase non- MD 415 volts Low Voltage MD 415 volts High Voltage MD 11Kv. High Voltage MD 33Kv.

    For now we only have prepayment meters for non-MD customers, that is, capacity ranges (i) and (ii) above

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Selection of Appropriate Meter Capacity

    The major determinant of what capacity of meter is required for a particular prospective customer is the installed load. Generally, a customer with installed load below 45 KVA is fed from public transformer and metered with single phase or three phase non-MD Meter depending on actual installed load. A prospective customer with installed load above 45 KVA is required to be on a dedicated transformer and metered with Maximum Demand (MD) meter, capacity of which depends on actual installed load and installed transformer capacity.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Selection of Appropriate Meter Capacity Contd.Before we can decide on adequate supply voltage and meter capacity we must be sure of the prospective customers installed load. We are supposed to be more knowledgeable than the customer in this regard. Hence, it is not for the customer to dictate the type of meter he needs rather it is our duty to advise the customer on supply voltage and meter capacity required based on the installed load. It is a common knowledge that someone will just walk into a Power Company office and say he wants three phase meter not because single phase cannot cope with his load but because he wants flexibility of changing from one phase to another. On the other hand, someone whose installed load requires three phase supply / meter will come to say he needs single phase meter simply because single phase connection fee and billing tariff are cheaper than those of three phase.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Selection of Appropriate Meter Capacity ContdIdeally, when a prospective customer applies for electricity supply by filling a Supply Agreement form, we should emphasize on the form being correctly filled showing details of customers installed load among other things. Then we have to carry out site technical inspection or load survey to confirm the information given on the Supply Agreement form and ascertain whether or not the available network capacity can still accommodate the intended additional load. At this stage capacity of meter required can also be confirmed.Based on positive outcome of load survey, the customer is issued Permit to Wire. After notification of wiring completion, Supply Authority carries out installation inspection and tests to ensure that the installation conforms to required standard. If okay, supply connection and metering are done. Necessary documentation follows and billing commences.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Meter Tampering and Security

    Some tampers bypass the meter, wholly or in part. Meters can be manipulated to make them under-register, effectively allowing power use without paying for it. This theft or fraud can be dangerous as well as dishonest.Meter readers are trained to spot signs of tampering, and with crude mechanical meters, the maximum rate may be charged each billing period until the tamper is removed, or the service is disconnected.A common method of tampering on older meters is to attach magnets to the outside of the meter. These magnetically saturate the coils or current transformers, preventing the alternating current from forming eddy currents in the rotor, or inducing voltages in the current transformer.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Meter Tampering and Security Contd.We also need to be vigilant in order to detect the following forms of tampering often done by dubious customers:Connecting part of the load on direct and leaving few on the meter to give impression that the customers consumption is being registered.Dropping meter shunt at certain period of the month when marketer is not likely to be around for meter reading or bill distribution and putting the shunt back before the next visit of the marketer.Bye passing the meter by connecting whole or part of the load onto the service cable before the metering point, in hidden places like when service cable passes through ceiling.In three phase metering, interchanging the supply and load cables on one phase. The overall effect of this is that only the consumption on one phase will be effectively registered in a balanced load situation.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Meter Tampering and Security Contd.Metering manipulation is deliberate distortion of meter reading in one or more of the ways stated above. All of these effects can be detected by the electric company, and many modern meters. This brings us to the critical issue of our marketers being adequately knowledgeable in the expected monthly consumption of each of their customers, given the level of supply availability during the month and also comparing with other customers of similar installed load or operation. For example, a customer with one bathroom water heater, two air conditioners and other electrical appliances, having meter reading consumption of 100 units in one month, is questionable. Even if the marketer cannot detect any shady deal, he or she should report in the office for proper investigation.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Meter Tampering and Security Contd.Also a customer that may be, had record of monthly consumption of 1,000 units in the first six months of being connected to the network but suddenly the consumption record drops to about 300 units. The marketer is expected to highlight such case for proper investigation.The supply authority normally secures the meter against tampering. Revenue meters' mechanisms and connections are sealed. One of the measures against meter tampering is to ensure that under no circumstance should any customer have access to meter terminal block. The terminal cover must be fixed and sealed. Any customer that breaks the seal must be penalized. As a measure to minimize meter bypass, we must ensure that under no circumstance is service cable allowed to pass through the ceiling or any other hidden places before getting to the meter. Experience has shown that many of the meter bypasses are done in such hidden places.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Meter Tampering and Security Contd.Newer computerized meters usually have counter-measures against tampering such as inverted installation, reversed or switched phases etc.Metering at Distribution Substation Transformer (statistical metering) with Automated Meter Reading: The meters are normally of very high accuracy and they often have sensors that can report opening of the meter cover, magnetic anomalies, alert the operator to tampering. Each oversees and records the consumption of the area the transformer serves. Power companies normally investigate discrepancies between the total billed and the total generated, in order to find and fix power distribution problems. These investigations are an effective method to discover tampering.Energy theft through metering manipulation is the most dangerous avenue of non-technical losses. Other forms of non-technical losses are meter accuracy deterioration, illegal direct connection and application of wrong (lower) multiplying factor in MD metering.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Load Factor Analysis for Maximum Demand Customers

    Load factor analysis is one of the means of detecting meter tampering and fraud by MD customers. Meeting meter seals intact during monthly meter reading is no more a guarantee that tampering did not take place in-between reading dates. Sealing wire and sealing lead can be purchased in open market. Experience has shown that some customers either forge sealing pliers or collude with dubious staff and get Supply Authority sealing pliers to enable them break seals at will, tamper with meters (MD and non-MD) and seal back. For MD meter reading use of numbered seals as against the conventional sealing lead is strongly recommended.Load Factor = Energy consumed within a specified period of Time Max. Demand x Power Factor x the period of Time

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Load Factor Analysis for Maximum Demand Customers Contd.L. F. = KWH KVA x pf x TimeWhere pf is assumed to be 0.8 and Time is total number of hours with the period under consideration e. g. 30 x 24 hours = 720 hours in a month or 365 x 24 hours = 8,760 hours in a year.Ideally, 0 < L.F. < 1. Expected load factor of a company on regular power supply and operating three shifts is at least about 0.7. Experience has shown that customers tend to be honest and law abiding within the first year of operation. It is good to analyze monthly load factor of each MD customer from inception. Any sharp drop needs to be investigated to confirm whether it is a genuine drop due to the customers operational problem / reduced power supply or a case of fraud.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Load Factor Analysis for Maximum Demand Customers Contd.

    For example, a customer with usual average consumption of 200,000 KWH and Maximum Demand of 500 KVA per month will have average load factor of 200,000 = 0.69 500 x 0.8 x 720

    If suddenly the monthly consumption drops to say 80,000 while MD remains at 500 KVA, it means the load factor has dropped to 80,000 = 0.28. 500 x 0.8 x 720

    Such a case needs to be investigated to confirm the genuiness or otherwise of the L.F. drop.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • Meter Calibration and Certification Meters are purchased by Supply Authority from many manufacturers. However, before the meters are used in the network they are subjected to accuracy tests in any of the Meter Test Stations in Oshodi (Lagos), Portharcourt and Kaduna. This is to protect the interests of both Supply Authority and the customers. Ideally, after fifteen years in circuit meters are believed to have lost some degree of accuracy and are therefore expected to be retrieved and sent back to Meter Test Station for recalibration and recertification. Thereafter they are sent back to Business Units for reuse.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • ConclusionIn any electricity industry, adequate and accurate metering of customers is a very crucial business that should not be viewed with levity if the industry must survive. It needs to be given the serious attention it deserves at all times. Hence, at the distribution / marketing level of electricity business, key roles need to be played in the survival of the Supply Authority and its workforce.

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

  • THE END

    Thank you for your attention

    Questions?

    NAPTIN, Power Trainer with a difference November 2013*

    NAPTIN, Power Trainer with a difference November 2013

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