MD300 and MT300. Technical Description

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3 CONTENTS 1. METER TYPE DESIGNATION TECHNICAL AND FUNCTIONAL DESCRIPTION BASIC MEASURING PRINCIPLE MEASURING SYSTEM Energy measurement with a SMART POWER SENSOR Measuring module FUNCTIONAL DIAGRAMS OF MT300 AND MD300 METERS Power supply stage with over-voltage protection EMC protection Three-phase measurement MEASUREMENT CHARACTERISTICS MEASURING VOLTAGE INPUT CONTROL CIRCUITRY Meter with logic gates as control circuitry Meter with microcontroller ENERGY REGISTRATION INPUT AND OUTPUT Pulse output Pulse divider stage Pulse length former stage Tariff changeover input PHASE VOLTAGE UNBALANCE INDICATOR METER CALIBRATION REGISTERS AND INDICATORS REGISTERS LED INDICATORS LOAD CURVES: INFLUENCE VALUES METER UPGRADING METER ENCLOSURE TERMINAL BLOCK POTENTIAL LINKS TECHNICAL SPECIFICATIONS CONNECTION DIAGRAMS / 24

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5 THREE-PHASE ELECTRONIC kwh METERS MD300 and MT300 A family of the MD300 and MT300 solid-state three-phase electricity meters belongs to a new generation of the Iskra monolithic electronic meters which are intended for domestic and small commercial applications. Active energy measurement: measurement of import energy in four-wire systems Tariff registration: energy is registered in one or two tariffs, Cyclometric registers: simple, robust and reliable registrations, Impulse outputs: standard impulse outputs allow remote transmission of meter measuring values to the data recording and processing equipment, (i.e.: ISKRAEMECO POREG 2), Functional upgrading: simple further upgrading with ISKRAEMECO TS 8 Ripple Control Receiver is possible for remote load control and tariff change-over, or ISKRAEMECO P2 communicator for TOU registration, load profile, maximum demand measurement and two way communication via telephone, CaTV or low-voltage network. Measuring characteristics: all measuring and technical characteristics comply with the IEC ( ) standard for active energy, class 2 or 1, for indoor and outdoor applications, Quality: the meters are manufactured in compliance with the ISO 9001 quality standards, therefore the uniform quality of the products can be guaranteed to the customers / 24

6 1. METER TYPE DESIGNATION M T D2 A V12 G12 - F M D T THREE PHASE ELECTRONIC kwh-meter electronic meter three-phase two-element meter three-phase three-element meter 300 meter with cyclometric register(s) D1 D2 A terminals for Imax = 85 A (direct connected meter) terminals for Imax = 120 A (direct connected meter) active energy 4 accuracy class 1 5 accuracy class 2 1 one direction energy measurement 2 two direction energy measurement V11 * V12 * G12 L11 F * Two-rate meters only. Single-rate meters have no additional mark. capacitor type voltage input for tariff change-over resistor type voltage input for tariff change-over impulse output: S0 type optoisolated impulse output: relay - Opto-MOS, make contact indication of phase voltage non-symmetry / 24

7 2. TECHNICAL AND FUNCTIONAL DESCRIPTION 2.1. BASIC MEASURING PRINCIPLE A measuring principle of ISKRAEMECO monolithic meters family (MT...and MD ) is based on the integrated Hall effect sensor. It ensures an accurate, time stable and reliable performance of the meter measuring functions. Hall effect, discovered in the year 1876, is typical phenomenon for semiconductors. Voltage (named Hall voltage) appears at semiconductor crystal sides when it is in a magnetic field and carries an electric current. This is a Hall effect sensor. If the sensor is placed into the magnetic field B(i) (which is generated by the load current) and current I(u) (proportional to the mains (load) voltage) flows through the sensor, then the Hall voltage is proportional to the electrical power of the load. Hall voltage is a vector product of load current and load voltage MEASURING SYSTEM Energy measurement with a SMART POWER SENSOR Smart power sensor technology: Iskra has developed an original and patent pending solution of the Hall effect sensor which is integrated into the same silicon chip together with digital and analogue electronics of the meter. The Hall effect sensor is used as current sensor as well as an analogue multiplier. With an appropriate configuration of the functional stages inside the chip a reliable and time stable smart sensor of the electrical power is obtained / 24

8 The analogue/digital electronics converts voltage of the Hall effect sensor into quantified impulses (Wh/imp) and compensates influences of temperature variations and Hall sensor non-linearity. The digital-processing part performs input/output and test functions of the measuring chip. Encapsulation: The IC (chip) is made in the MOS technology and is encapsulated into a hermetic ceramic case. This assures high resistance of the IC to ambient climatic influences and long life Measuring module LEGEND: 1. Magnetic system holder 2. Spring 3. Ferite core 1 4. Current loop 5. PCB 6. Ferite core 2 7. Isolation plastic 8. Magnetic shielding 3 1 The measuring module of the MD300 and MT300 electricity meters consists of the measuring IC (Smart Power Sensor based on the Hall effect sensor) and the current electromagnet, made of a high quality magnetic material. Load current I flows through a current loop of the electromagnet, which generates a magnetic field in the core air-gap. The IC is positioned in the core air-gap. The current loop is separated from the meter electronics therefore the influence of mains-borne disturbances to the meter performance are negligible. A heavy gauge magnetic shield protects the measuring element from external magnetic fields. The MD300 electricity meters are equipped with two measuring modules connected in phases R (L1) and T (L3); the MT300 electricity meters are equipped with three measuring modules / 24

9 2.3. FUNCTIONAL DIAGRAMS OF MT300 AND MD300 METERS Single tariff MT300 meter kwh imp/kwh Single tariff MD300 meter kwh imp/kwh / 24

10 Double tariff MT300 meter 1 kwh imp/kwh 2 kwh Double tariff MD300 mete 1 kwh imp/kwh 2 kwh / 24

11 Double tariff MT300 meter with microcontroller 1 kwh imp/kwh 2 kwh non-simetry indication µc output Double tariff MT300 meter with microcontroller 1 kwh imp/kwh 2 kwh µc output Note: The pulse output is optional. The electronics of the measuring elements is situated on the same PCB together with a mains power supply unit and over-voltage protecting devices, LED indicators, registers with step motors and impulse outputs / 24

12 Power supply stage with over-voltage protection The RC type power supply stage is supplied with all three phase voltages, therefore the meter functions even if the two of them or a phase and neutral fail. It assures enough power for normal meter operation in a specified range, even in worse conditions (only one phase voltage applied, at voltage level 0.8 Vr ). The meter electronic circuits are supplied with 5.6 V DC ± 5%. The voltage inputs are protected against over-voltages by metal-oxide varistors EMC protection The meter is designed for high level of EMC immunity. This is achieved by high degree of integration of electronic circuitry (single chip meter), selected measurement method (Hall-effect sensor / multiplier), high-frequency suppressors, over-voltage protections of the inputs and the PCB lay-out Three-phase measurement Active energy is measured in each phase separately in single-phase mode. A part of a measuring chip in the phase T (L3) is programmed (by the signal on the mode selection input) as a summator of metering pulses from all phases. The result is three-phase energy. The required synchronisation between three ICs is achieved by the system clock frequency supplied from the crystal oscillator in the IC in one of the phase circuitry. A number of pulses at the output of the summator generated per kwh depends on reference voltage Ur, basic current Ib and maximum current Imax is called a meter constant km. Measured values Meter constants km Ur Ib Imax LED V A A T=32ms imp/kwh 3x V or x V 5 85 or / 24

13 3. MEASUREMENT CHARACTERISTICS 3.1. MEASURING VOLTAGE INPUT Measuring (voltage) inputs: the measuring ICs are connected to the phase voltage via resistive voltage divider. The line voltage is reduced to the 5.6 V level by the chain of the high quality metal oxide resistors. The inputs are over-voltage and EMC protected CONTROL CIRCUITRY Depending on the requested meter functions the control circuitry is available in two versions: with logic gates with a microcontroller Meter with logic gates as control circuitry The meter measures only imported active energy (+P) The pulse LED is controlled by the output of measuring IC, together with the logic gates. The pulse width is 32 ms. The step motor of the register is controlled by the output of measuring IC. The pulse output is controlled by the output of measuring IC, together with the logic gates Meter with microcontroller The meter can measure active energy in one energy flow direction (imported) or in two energy flow directions (imported and exported). The pulses from the measuring IC are fed to the microcontroller input. In case of one energy flow-direction meter only pulses of imported energy are considered. In case of two energy flow-directions meter the microcontroller counts separately pulses of imported and exported energy. Imported energy is registered on the left register while exported energy is registered on the right register. Which energy is being registered is indicated with a lit LED by the corresponding register. If registered energy is lower than the threshold energy or there is no load at all (the status is indicated with lit pulse LED) no energy flow direction LED is lit. In case of one energy flow-direction two-rate meter the microcontroller detects valid tariff and register consumed energy at the corresponding register and turns-on the tariff LED indicator. Two energy flow-direction two-rate meter version does not exist / 24

14 The microcontroller outputs together with corresponding software drive the meter pulse LED, the step motor(s) and either S0 or optomos relay pulse output. The following meter parameters are programmable with the microcontroller software: One energy flow-direction meter or two energy flow-directions meter Pulse length on the pulse LED (in the range from 0.5 ms to 125 ms) The pulse constant of the pulse LED (all integers up to 255 times smaller than the pulse constant of the measuring IC.) Pulse length on the pulse output (in the range from 1 ms to 32 ms) The pulse constant of the pulse output Pulse length for feeding the step motor (in the range from 1 ms to 125 ms) The pulse constant of the pulse LED (all integers up to 255 times smaller than the pulse constant of the measuring IC.) Starting current (by setting the time between pulses of the metering IC required that meter turns from disabled to enabled metering) Single-rate or two-rate meter version The double-rate meter versions for change-over the tariffs are available: when voltage is applied to the tariff control input the high tariff is valid or the low tariff is valid ENERGY REGISTRATION The meter registers measured energy on one or two cyclometric registers, depending on a number of tariffs or energy flow directions INPUT AND OUTPUT The kwh-meter is optional equipped with auxiliary terminals 20 and 21 for a pulse output. The two rate kwh-meters are equipped also with auxiliary terminals 13 and 15 or just 13 (in this case neutral from the meter is used as ground) for tariff change-over Pulse output The pulse output is used for remote transmission of quantified metering pulses Wh. The kwh-meter is provided with two optional types of pulse outputs: S0 type: maximum transmission distance: 0.5 m - optoisolated, complies with standard DIN , standard pulse length is 32 ms (other pulse length is available on request) Relay type: maximum transmission distance: 1 km - solid state - Opto MOS, make contact, standard pulse length is 80 ms (other pulse length is available on request) Both pulse constant value and pulse length value can be set in a certain range. At the kwh-meters with built-in a microcontroller it controls the pulse output, therefore pulse length and pulse constant are programmed. At the kwh-meters without a microcontroller the pulse output is controlled by metering pulses at the output of the metering IC. If non-standard pulse length and/or pulse constant is required at these meters, they are equipped with a pulse length former and/or a pulse divider stage / 24

15 Pulse divider stage The pulse divider stage consists of a 7-bit binary counter and a logic circuitry. It divides a number of pulses with an integer up to 127. A divisor is set by connecting diodes at the corresponding outputs of the binary counter, so that required pulse constant is obtained. The pulses at the input and the output of the binary counter are of the same length. Possible pulse constants: Divisor Direct con. meter Ib=10A km = 1000 pls/kwh PULSE CONSTANT (PLS/KWH) Direct con. meter Ib=5A km = 1250 pls/kwh Transf. operated meter km = 10,000 pls/kwh km - meter constant Pulse length former stage The required pulse length in range 20 ms to 1500 ms can be set with a flip-flop, a resistor and a capacitor of corresponding RC constant. The following pulse lengths can be set with tolerance ±15%: 20 ms, 30 ms, 40 ms, 80 ms, 100 ms 250 ms and 1500 ms. When non-standard pulse length and constant are required attention should be paid that pulses are not overlapped Tariff changeover input The two-tariff meter versions have an input for tariff changeover. It is isolated from the meter electronics by an optocoupler Two versions of the tariff input are available: resistor and capacitor type. The line voltage applied to the tariff input is reduced with resistor or capacitor voltage divider. Tariff changeover input is protected against over-voltages with a metal-oxide varistor. Status on the tariff change-over input is: ON if applied voltage is U 0.8Ur OFF if applied voltage is U 0.2Ur Burden of the tariff change-over input is less than 0.5 W at 230 V PHASE VOLTAGE UNBALANCE INDICATOR A phase voltage unbalance indicator is built-in only at the MT300 meters. Three separate resistor line voltage dividers wye-connected are used for phase voltage non-symmetry indicator. When the voltage in any phase differs more than 80% from the other two voltages, or it fails, the indicating LED is lit / 24

16 4. METER CALIBRATION Meter calibration is made in voltage inputs of the measuring system. A part of the resistor divider is used for meter calibration by inserting resistors of corresponding values. Calibration is fixed, no meter re-calibration is needed in the entire life time of the meter. 5. REGISTERS AND INDICATORS Name plate of a single-rate kwh-meter 3 pulse LED 4 voltage unbalance indicator / 24

17 Name plate of a two-rate or two energy flow-directions kwh-meter 1 first tariff or imported energy LED indicator 2 second tariff or exported energy LED indicator 3 pulse LED 4 voltage unbalance indicator 5.1. REGISTERS The MD300 and MT300 meter has one or two cyclometric registers with 7 drums (6 + 1 decimal). The decimal drum is marked with a red frame on the name plate. On request the decimal drum is coded or covered with the name plate. The decimal drum has 100-division marking on its rim. The digits height is 4.7 mm. The step motor of the register is shielded against external magnetic fields LED INDICATORS There are up to 4 LEDs on the name plate depending on the version of the MD300 and MT300 meter. Table 2: Pos Function Marking* Colour* State Indication 1, 2 register activity I, II green lit tariff I or II is active, exported or imported energy 3 starting current imp/kwh red lit load current is bellow starting level meas. pulses Pulsating impulses/ kwh 4 line voltage unbalance red lit three phase voltage unbalance *NOTE: markings and colour of LED-s could be different on special request / 24

18 5.3. LOAD CURVES: Ib = 5 A, Imax = 85 A cosϕ = 1 cosϕ = 0,5 Ib = 5 A, Imax = 120 A cosϕ = 1 cosϕ = 0,5 ind Transformer operating meters cosϕ = 1 cosϕ = 0,5 ind / 24

19 5.4. INFLUENCE VALUES Temperature variations: I = I b Voltage variations: cosϕ = 1 cosϕ = 0,5 ind I = I b Frequency variations cosϕ = 1 cosϕ = 0,5 ind I = I b 6. METER UPGRADING A meter can be subsequently upgraded with a Ripple Control Receiver (ISKRAEMECO TS 8) for remote tariff and load control. It can be added at any time to the meter in final installation by replacing the terminal cover with an adapter plate. It is not necessary to remove the meter. Also a data logger Iskraemeco P2S can be mounted instead the RCR / 24

20 7. METER ENCLOSURE The meter enclosure consists of the meter base with integrated terminal block, meter cover and terminal cover. All parts of meter enclosure are made of high quality, self-extinguishing polycarbonate, which has excellent mechanical and insulation characteristics. Meter base and terminal cover are natural gray, meter cover is transparent. The protection level against water and dust penetration is IP53. Internal assembly: All internal parts of the meter (PCB, mechanical registers, measuring elements) are fixed to the meter base with the snapping pins. Aluminium name plate is fixed to the extensions of the frame of the mechanical register(s). Meter installation, overall and fixing dimensions: The overall and fixing dimensions correspond to the DIN standard. The meter hook is moulded as an integral part of the meter base. A meter base with fixing hook under the upper edge is available as an option, for the installations where the meter is installed directly under the ceiling of the installation cabinet. Meter Sealing: Both meter and terminal cover are fixed with two sealing screws, so that an access to the meter interior or terminals is not possible without breaking the seals. The sealing screws are captive / 24

21 8. TERMINAL BLOCK The terminal block is designed as a part of the meter base. It is equipped with current terminals (85 A or 120 A for direct connected meters) and auxiliary terminals. Current and auxiliary terminals are made of solid brass. The terminals are nickel-plated if tropical meter version is required. Current terminals have two fixing screws with a flat slot or combined pozidrive 2 / flat slot head. The terminal holes - see table 4: Table 4 Terminals Imax max. of wire num. numbering Current 85 A 8.5 mm 8 1,3,4,6,7,9,11,12 Current 120 A 9.5 mm 8 1,3,4,6,7,9,11,12 Auxiliary 5A 2 mm 4 13,15,20,21 *NOTE: numbering of auxiliary terminals can be different according to the customer request. For the standard numbering - see connection diagrams. On request a terminal or terminals for power supply of an add-on unit is/are attached POTENTIAL LINKS Voltage circuits of direct connected meters are connected to the current terminals via potential links. The potential links can be positioned either in the terminal block compartment or under the meter cover. They should be in its left position (voltage circuit is connected to the corresponding current terminal) during meter operation; during meter calibration they should be in their right position (voltage circuit is disconnected from the corresponding current terminal. The potential links are fixed with two screws / 24

22 9. TECHNICAL SPECIFICATIONS Accuracy class CL 2, 1 - for kwh-meter (IEC 61036) Basic current Ib 5A, 10A, 15A, 20A Maximum current Imax Up to 85 A or up to 120 A Thermal current Ith 1.2 Imax Starting current <0.005 Ib - for Ib = 5 A <0.004 Ib - for Ib = 10 A Short-circuit current 30 Imax Reference voltage* Ur 3x220/380V, 3x230/400V, 3x240/415V; 3x220 V, 3x230 V, 3x240 V *other voltages on request 3x110/190V, 3x120/108V; 3x120 V Voltage range 0.8 Ur Ur Reference frequency Fr 50 Hz or 60 Hz Meter constants Km 1000 imp/kwh, Ib=10A 1250 imp/kwh, Ib=5A Operating temperature -40 C C Storage temperature -50 C C Consumption: voltage circuit < 1 W / 10 VA current circuit < 0.5 VA Resistance against electromagnetic disturbances: Dielectric strength 4 kv, 50 Hz (or 60 Hz), 1 min Electrostatic discharge 15 kv (IEC ) HF electromagnetic field 10 V/m (IEC ) Burst test 4 kv (IEC ) Impulse voltage main terminals 12 kv, 1.2/50 µs (IEC 61036) auxiliary terminals 6 kv, 1.2/50 µs (IEC 61036) Impulse outputs: S0 optoisolated (DIN 43864) Ti = 32 ms relay - OptoMOS open collector - make contact Ti = 80 ms, (other Ti on request) max. switching voltage 250V AC max. switching current 100 ma max. switching power 25 VA Tariff change-over inputs: voltage controlled Overall dimensions Mass OFF 0.2 Ur ; ON 0.8 Ur 327 x 177 x 79 mm approx.: 1.2 kg / 24

23 10. CONNECTION DIAGRAMS Direct connected meters / 24

24 Owing to periodical improvements of our products the supplied products can differ in some details from data stated in the document. Iskraemeco, Energy Measurement and Management 4000 Kranj, Savska loka 4, Slovenia Telephone: (+386 4) , Telefax: (+386 4) Published by Iskraemeco, Marketing Data subject to alternation without notice Mt300_Ang_V1_PDF / 24