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| What is the difference between an induction-type watt hour meter and an electronic watt hour meter? |
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① An induction-type watt hour meter makes turning force occur on a rotating disc in proportion to electric power so that it adds the used hour of power by the number of rotations and it usually measures effective power. |
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② An electronic watt hour meter makes voltage and current work through a semi-conductive device to generate output
pulse proportional to measured energy and it is possible to measure effective and reactive power and power factor
according to its type. |
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| What is official approval? |
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A To prevent the distribution of a poor meter and secure a sound order of commercial transaction, it is an action that tests whether a device is in conformance with the standards prescribed in the laws for the performance, error, etc. of
a meter. |
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| How long is the validity of official approval to a meter? |
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① It is 15 years for the type IV(400%) and 7 years for the type II(200%) and type III(300%) of an induction-type watt hour meter. And it is possible to check a type among them with the ratio between the numbers inside and outside a parenthesis such as “40(10)A” on a name plate of a meter. |
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② It is 7 years for an electronic watt hour meter. |
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③ And it is 8 years for a water meter and 6 years for a warm water meter for heating(heating flowmeter). |
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| What is the precision of a watt hour meter? |
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It is Class 2.0 for an induction-type watt hour meter and Class 1.0 for an electronic one. It can say that the lower precision is, the less tolerance is to be more precise.
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| What’s the meaning of AC single phase & 2 wire, 200V 40(10)A 60Hz 500rev/kWh indicated on the name plate of an induction-type watt hour meter? |
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① It indicates the conditions of rated use of an induction-type watt hour meter and means that the meter can be used at
alternate current of the voltage of 200V and the frequency of 60Hz. And as the number outside the parenthesis in the
indication of current is rated current, it is the max. applicable current within a tolerance and as that inside the
parenthesis is basic current, meters are classified into Type II, III and IV according to the proportion between rated
and basic currents. The existing law prescribes that precision be guaranteed up to the range of 5% of basic current
under a given condition (except Type II attached with a metering outfit). |
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② 500rev/kWh means that a disc rotating in a meter revolves 500 times to measure and add 1kWh. |
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| What’s the meaning of AC single phase & 2 wire, 220V 40(10)A 60Hz 1200pulse/kWh indicated on the name plate of an electronic watt hour meter? |
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① It indicates the conditions of rated use of an electronic watt hour meter and means that the meter can be used at alternate current of the voltage of 200V and the frequency of 60Hz. And as the number outside the parenthesis in the indication of current is rated current, it is the max. applicable current within a tolerance and as that inside the parenthesis is basic current, it is standard current according to the meter’s regular operation and test. |
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② 1200pulse/kWh means that the LED on the right of the meter turns on and off 1,200 times to measure and add
1kWh. |
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| How read the number and scale of an added value of a meter? |
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① The number of an induction-type watt hour meter has a five-digit number as its added value. It indicates a case that the value of overall load is less than 10kW and does up to one decimal place for a meter attached with a metering outfit and included are 5A, 30A and 40A by rated current of a single-phased meter and 5A of a three-phased meter. |
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② All types of electronic watt hour meters indicate up to one decimal place
(except the standard meter for Korea Power Corp.). |
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③ A water meter and a warm water meter have 8-digit values and indicate up to four decimal places. |
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| Is it not possible to telemeter an induction-type watt hour meter? |
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Although an induction-type watt hour meter can not be applied to telemetering by itself, it can be applied to telemetering by attaching a sensor inside the measuring device to output a pulse signal. |
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| What’s the difference between an addition calorimeter and warm water meter (flowmeter for heating)? |
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① A calorimeter calculates the value of calories by multiplying the passed flow of warm water(㎥) and temperature difference between a supplying and a receiving party(ΔT) to a calorie conversion coefficient corresponding to the temperature difference(k), and a warm water meter for heating measures only the passed flow of heating water. Therefore, the indication unit of an addition calorimeter is MWH or Mcal and that of a war water meter for heating is ㎥. |
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② Although it is possible for an addition calorimeter to bill a charge rationally by calculating heating expenses with the calorie used in a household, it is expensive and has a high frequency of breakdown due to its complicated structure and causes the billing of an excessive charge for common heating expenses. Although a warm water meter for heating measures only passed water regardless of temperature, it is less expensive and has a lower frequency of breakdown and more convenient in calculating a heating charge than an addition calorimeter. |
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| What is the meaning of Q3=1.6㎥/h Q2/Q1 = 6.3 Q3/Q1 = 40 indicated on a name plate of a water meter? |
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① As it is indicated according to the standard of type approval to a water meter (Notice No. 2006-514, Technology and Standards Institute), the max. flow(Q3) means the greatest applicable flow that the meter can operate without exceeding its max. tolerance, the transfer flow(Q2) means that the max. tolerance can be divided into a wide and a narrow ranges as the flow between Q1 and Q2, and the min. flow(Q1) means the lowest flow that the meter can operate without exceeding its max. tolerance. |
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② As a result, Q3/Q1 is the ratio between the max. and the min. flows and indicates the measuring range within a tolerance of a water meter and the ratio of Q2/Q1 indicates the position of flow to the range that a tolerance fluctuates. |
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| What is the difference among the methods of PLC, RS-485 and RF of the AMR system? |
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As the expression for the transmission method of AMR data, |
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① PLC is called as power line communication and as it uses a power line as its communication medium, it is not required to install additional line but it still has the disadvantages of limited speed and interruption effect of the power line itself. |
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② As RS-485 is a TIA/EIA standard for a communication line with multiple points, it conducts telemetering through an exclusive line and is generally used for telemetering now. |
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③ RF(Radio Frequency) is usually expressed as wireless or radio frequency communications. Although this method doesn’t need a communication line, it cost some expenses to install radio communication function to a meter for
a household. |
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| Is it possible to check an AMR system remotely in the Internet? |
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Yes, but it is optional so that it needs to be decided prior to the construction of an AMR system. |
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| Is it required to use a separate pipe from a power line for an AMR system? |
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The communication line for an AMR system needs to be separated from a power line (AC220V or 380V) for use. If a communication line is used inside one pipe together with a power line, it may cause an communication error and measuring error.
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| What’s the difference between OMR and AMR? |
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① As OMR(off-site meter reading) is a short-distance radio communication method as a kind of the RF communication, it needs to request a manual measuring for metering and then to be responded from the meter and there is a limit on the distance. |
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② AMR(automatic metering reading) doesn’t mean a communication method but it includes all communication methods that telemetering is automatically conducted through automatic communications between an AMR server and a meter per unit time.
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| How can I fix if a watt hour meter doesn’t operate? |
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Please, check the wiring condition between a power line and terminal block. And please, check whether the electricity failed or a breaker is off.
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| There is lots of noise in an induction-type watt hour meter. How can I fix it? |
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Please, check whether the meter is broken or it is installed properly. |
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