Basic Characteristics– 3-phase measurement and calculated quantities U, I, P, Q, S, cos ϕ, f– measurement accuracy of 0.2 and 0.5 %– measurement and recording parameters in compliance with the CSN

EN 50160 standard and the ERU (Energy Regulator) notice Nr. 306– time integral of short-term and long-term voltage dips and supply

outages, number of events– fault time record of selected measured and calculated quantities (up

to 4 independent quantities) with time resolution 10 ms and variabletrigger and blocking condition.

– registers of measured active and reactive energy - multi-level archiveof measured values MIN, MAX, AVERAGE (3 sec, 10 min, 1 hour,24 hours, 1 month)

– distribution transformer operational state - temperature and oil level,Buchholz relay, interrupted MV fuse, temperature/power characteristics

– remote warning signalling of up to 16 parameterisable conditions (selec-tion from the whole set of measured and calculated quantities), evaluat-ing of exceeding or decreasing adjusted comparison levels, with its owndelay and hysteresis - eg. I>, THDu>, THDi>, URMS<>, IRMS>, etc.

– remote fault signalling (self-diagnostics of MDT, DistributionTransformer (DT) overload, supply outage at secondary side)

– remote parameterisation of functions and measuring procedures fromcontrol centre, reload MDT firmware with new features (e.g. due tolegislative changes)

– local parameterisation of functions using PC notebook– communication to control centre using GSM/GPRS/SMS/CSD– PC SW for local parameterisation and off-line evaluating of recorded

values.– external MDT-GPS module for time synchronisation from GPS

satellite system.

MDT Block DiagramThe device is based on the DSP single-chip processor with support circuits. The

memory of stored data is a non-destructive type FLASH, RTC module with back-up for dead state record. It has three serial communication channels – local IrDAinterface for notebook parameterisation and visualization software (MDT-Navigator, PQ-MASLITE), remote signalisation and data transfer (integrat-ed GSM SMS/GPRS modem with built-in or external antenna) to the region-al dispatching centre control system, and connection to local transformersubstation control system (RS485, optics)

The MDT is equipped with two-level alarm determined to local signalisa-tion of alarm and fault reports (2 independent relays with galvanically sepa-rated contacts for any user programmable purpose) and with one fault relay(line fault, according to the parameterisation).

Measured and calculated quantities (including archives, fault and alarmevents) are visualized on the LCD graphic display (128 x 64 points in inversemode with high contrast). Functions of membrane keyboard buttons are con-trolled dynamically and described directly on the LCD display. Measuring partof the MDT includes blocks of voltage, current, binary and auxiliary inputs.

Three voltage inputs (secondary voltage of the Distribution Transformer -DT) with possible permanent overload capacity of 200 % are high-qualityresistor dividers (for higher harmonics analysis) with dynamic ranges of 230 V,100 V and 100 V/√3 AC.

For 3-phase currents measurement (DT secondary side) the 3 Rogowskicoils are used (advantages: wide dynamic range, linearity, simple installation).

MDT 9.e (i) DISTRIBUTION TRANSFORMERS MONITORING DEVICEThe device is intended for continuous power quality measurement. It provides statistical 3-phase record of measured and calculat-ed quantities of U, I, P, Q, S, E, f, T and power quality evaluation at the low voltage side of a distribution transformer and evaluationof non-standard operational states of this transformer in medium voltage overhead and cable networks.

Pic.: MDT 9 Block Diagram

Analog integrators of the Rogowski coils are part of the MDT electronics.The dynamic range of current measurement is defined by SW parameterisa-tion. For connection to standard current measuring transformer (MTP) with sec-ondary output of 1 A/5 A special MTI25 current sensors are to be used.

MDT_GPS external module (with built-in GPS receiver) can be added for pro-viding precision time synchronising of DT operating measurement. MDT_GPSmodule over RS485 data measuring interface inserts DT complex measurementto standard power quality measuring.

For DT temperature measurement, according to DT equipment, Pt100 sen-sor or pyrometric sensor or smart sensor with data output is used. The tem-perature measurements - DT temperature, ambient temperature, estimation ofthe DT HotPoint and winding temperature) are a basis for determination of theDT lifetime or wear in compliance with relevant standards and regulations forthe DT operation.

Auxuliary binary inputs are decoupled by optocouplers and they are user’sprogrammable, e. g. for binary report like Buchholz relay, switchboard cubi-cle open, maximum temperature reached etc.

Auxiliary supply is provided at the same time from three measuring volt-age inputs or from an independent input. The supply circuit is AC/DC (alter-natively DC/DC) type with backup by a capacitor battery for up to 60 sec offull operation in case of total blackout.

Both hardware and software self-diagnostics of failure-free state, fault sig-nalling and CPU independent WatchDog circuit, necessary for reliableoperation, are built-in.MDT Design

MDT is produced in two models. The MDT9 is to be mounted either into a pan-el instead of classic directly indicating current measuring devices into switchboards (MDT 9i) or on the panel in a compact design (MDT 9e).MDT Programme Equipment

Firmware x.x version is included in MDT delivery. According to user´s spec-ification, there are following basic software modules available:– Basic power quality measurement I.

(see EN 50160, ERU306) Periodical quantities (URMS, UASYM, THDU, f) Indicative quantities - events (short-term drop in voltage, over-

voltage, interruption) Measurement of IRMS, THDi, P, Q, S, E, cos ϕ supplementary

extension– Alarm signalling from up to 16 fully programmable conditions (selec-

tion from all of measured and calculated quantities including evaluationof exceeding adjusted comparison levels and itself delay and hysteresis)

– Fault record - very effective tool for supplementation of eventreport with analog record of URMS, IRMS, Ipeak, P, Q, S, f quantities(parametrisable in prediction, overall lenght, record step, quantitiesselection) - at the same time up to 4 mutually independent types offault records are available.

– Extended power quality measurement II. Periodical quantities (UHARM up to 50. harmonic, UNONHARM,

mains frequency voltage, UHDO, (ripple controll), Psh, Plt flic-ker, IHARM up to 25. harmonic, INONHARM)

– Extended multilevel archive of measured values MIN, MAX,AVERAGE (3 sec, 10 min. 1 hour, 24 hours, 1 month)

– DT statistics and life-time (IEC 60354) – supplement measurementand evaluation of TDT, TWND and THotPoint quantities

– Reload (local or remote) - possibility of firmware change - SWupgrades, legislative or quality parameters changes

– Remote communication - using GSM/GPRS/CSD

MDT-Navigator – for PC notebook service and parameterisation. Forreading of local on-line measured data (table and roll-scope view,harmonics bar graph), local and remote reload and parametrization

PQ-MASLITE – reading and evaluation of saved data (archive, faultrecord)

PQ-MAS – SW pack for remote data download using the GSM GPRSprotocol and signalling via SMS. Software is either as a module inte-grated into Control and Information System of the Control Centre orinstalled in a separate data concentrator and connected through stan-dard LAN interface into Control Centre System. This solution isindividual according to the software and hardware equipment at theregional control centre.

MDT Accessories– MDT-10.I external module - an expansion of number of measured

currents that allows measurement of further ten currents includingtheir harmonic analysis (THDI )

– optional integrated GPS module for time synchronization and sup-plement measurement of DT

MDT Technical ParametersMeasuring Inputs:Frequency measurement. . . . . . . . . . . . . . . . 50 Hz, 60 Hz

Dynamic range . . . . . . . . . . . . . . . . . . . . . ±5 HzMeasurement accuracy . . . . . . . . . . . . . . 0.05 Hz

Voltage measurement . . . . . . . . . . . . . . . . . . 100 V/√3, 100, 230, 400 V,other

Voltage input overload cap. (continuous) 1.3x UNMaximum peak voltage . . . . . . . . . . . . . . 5x UN / 100 msRMS voltage measurement accuracy . . . . Ui_RMS < 0.2 %

(5 % up to 130 % UN)Current measurement:Rogowski coil RgMTI . . . . . . . . . . . . . . . . . 0 – 3000 A, 10 – 2000 HzMTI25 (for MTP 1 A/5 A output) . . . . . . . . 1 A, 5 A, optional

Current input overload cap. (continuous) 1.3x INMaximum peak current. . . . . . . . . . . . . . . 200x IN / 100 msCurrent input impedance . . . . . . . . . . . . . <0.1 Ω

RMS current measurement accuracy . . . . . . Ii_RMS <0.5 % Power P measurement accuracy . . . . . . . . . < 0,5 %Temperature measurement:temperature T ambient - dyn. range . . . . . . . –30 up to +55°Cmeasurement accuracy . . . . . . . . . . . . . . . . . ±2°Ctemperature T DT (Pt100) . . . . . . . . . . . . . . (contact method)

dynamic range . . . . . . . . . . . . . . . . . . . . . –40 up to +250°Cmeasurement accuracy . . . . . . . . . . . . . . . ±2°Cunified signal: . . . . . . . . . . . . . . . . . . . . . . 4 up to 20 mA

Temperature T DT (Pyrometric sensor) . . . (contact free method)dynamic range . . . . . . . . . . . . . . . . . . . . . –20 up to +270°Cmeasurement accuracy . . . . . . . . . . . . . . . ±2,5 %,covers area of cca 100 mm at the distance of 580 mm

MDT outputsBinary outputs (output relay) . . . . . . . . . . . . 2+1 (ALARM1, 2, Error)

Galvanic relay contact . . . . . . . . . . . . . . . 1 opening/closing contact -optional

Maximum ratings . . . . . . . . . . . . . . . . . . . 230 V AC/DC, 30 VDC/2 Acontinuous, 0.5A/125 V AC

Closing/opening ability. . . . . . . . . . . . . . . 60 W/VA / 15 W/VAData communication interface:Implemented protocols . . . . . . . . . . . . . . . . . SADS Com 3.0, IEC 870-5-

101(4), Modbus, Spabus, oracc. to customer’s spec.

Physical communication layer: . . . . . . . . . . GSM/GPRS/CSD, GSM-SMS, RS485, optic fibre

Optic interface (Fiber optic) . . . . . . . . . . . . . 820 nm, 4000 m, ST, HFBR2400T

serial interface IrDA (notebook, PDA). . . . . according to the IEC 1107Visualization of states and measured quantitiesDisplayed LED diodes . . . . . . . . . . . . . . . . . ALARM1, 2, Error, Ready LCD graphic display . . . . . . . . . . . . . . . . . . 128 x 64 pixels, blue-whiteAuxiliary supply: . . . . . . . . . . . . . . . . . . . . . 80 up to 240 V AC/DC,

24 up to 85 V AC/DCPower input. . . . . . . . . . . . . . . . . . . . . . . . . . <10 VAbackup time (at 100% regeneration) . . . . . . 60 sec

backup type. . . . . . . . . . . . . . . . . . . . . . . . capacitors (no cell)EMC (electromagnetic compatibility):according to the EN 61000-4-x - class IVClimate conditions:Working temperature . . . . . . . . . . . . . . . . . . –25 up to +75°CStorage temperature . . . . . . . . . . . . . . . . . . . –40 up to +75°CRelative humidity . . . . . . . . . . . . . . . . . . . . . 25 up to 95 %,

without condensationDesign (w x h x d):MDT9e Al alloy case . . . . . . . . . . . . . . . . . . . . . . . . . 220 x 130 x 60 mmProtection . . . . . . . . . . . . . . . . . . . . . . . . . . . IP 54Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . acc. EN 50 022, on panelWeight: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.87 kgMDT9iUV plastic, self-snuffing. . . . . . . . . . . . . . . . 96 x 96x 160 mmProtection . . . . . . . . . . . . . . . . . . . . . . . . . . . IP 20 (front IP54)Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . acc. EN 50 022, into panelWeight: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.45 kgMeasurement accuracies are related to the nominal input values at the

temperature of 25°C and 55 % of relative humidity.Technical changes reserved

INVENTION:Automatic power quality data (periodic measurements and events) trans-

mission according to the EN 50160 over GSM/GPRS. Extensive accompany-ing utility (alarms, fault records, DT measurement).

EGÚ ČB, a. s., Power Institute České Budějovice, Dienzenhoferova 2, 370 06 České Budějovice, Czech Republic 02 2006

Tel.: (+420) 387 000 111, Fax: (+420) 387 410 193, e-mail: egu@egu.cz, http://www.egu.cz