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Transformer diagnostics: MT-3

Transformer diagnostic devices

Thanks to the co-operation with the B&C Diagnostics company, a completely new measurement construction dedicated to transformer diagnostics has been developed.

Basic characteristics of MT-3

This device has replaced the previously produced MT-1 and MT-2 instruments. Thanks to its new technical solutions the MT-3 allows for significantly simpler and faster diagnostics. The relay matrix used as well as the system of measurement cables, enables fully automatic measurements to be undertaken for the most common transformers and, as a result, there is no need to modify the measurement set-up i.e. re-clipping of wires.

No matter which parameter is to be measured and which tap position (or range of taps) is desired, the software will select an appropriate source, set up a proper circuit and control motor-drive to obtain appropriate measuring conditions.

Significant progress comparing previous versions (MT-1 and MT-2) as well as devices produced by competitors, is the three-phase measurement of the transformer ratio and magnetizing currents.

The modification significantly shortens measurement time. An important feature of the MT-3 is security against destructible activity of over-voltage caused by circuit break whilst measuring winding resistance. The used cabling method minimizes the risk of accidental opening of the circuit during measurement and together with electronic protection practically liquidates the risk of damage.

Software

The wide experience gained during the development and operation of previous MT series instruments enabled the creation of well-designed software. The application controls all parameters during measurement, but also assists the user in the analysis and evaluation process of results obtained. The software allows the user to avoid unnecessary work by calculating deviations, converting temperatures and comparing the values obtained to previous results.

It is worth mentioning that there is the possibility of comparing registered current curves of the diverter switch that allows for precise tracking of changes of the technical condition of diverter switch.

Functions of MT-3 measurement application:

graphically displayed results
report of measurements undertaken
automatic comparison of measurement results to previous values (factory values, previous measurements)
advanced procedures of results analysis

Value examined	Accuracy
Measurement of motor drive inherent delay Measurement of power switch time	Resolution measurement time 0,1ms
Winding resistance measurement Technical method in accordance PN-81/E-04070.05 standard	Scope of measurement 0,001 Ω - 100 Ω Resistance precision measurement 0,2% Voltage and current precision measurement 0,1%
Measurement of transformer ratio in accordance with PN-81/E-04070.06 standard	Measurement precision of transmission 0,2%
Magnetizing current measurement	Precision of current measurement 0,2%
Operation parameters	Allowable values
Scope of operation temperature	-15 ... 45^oC
Personal computer	PC LAN (IPX/TCPIP protocol)
Supply voltage	230V AC +10% -20%
Weight	8,5 kg

Construction

In the MT-3 construction, typical computer components and measuring card have been replaced by a specialized system designed and produced by Diagnostics from Hungary, for use in transformer diagnostics instruments. Thanks to this, substantially increased precision of measurements have been obtained together with the elimination of additional external power sources for the measurement of winding resistance.

Usage of the system mentioned allows for substantial reduction of the dimensions and weight of the equipment.

In the MT-3 device, data acquisition and signal processing take place in the measuring part of the instrument. Controlling of the measurement process and visualization of the measurement results is undertaken by an additional computer (usually a laptop). Communication between the MT-3 instrument and the computer takes place via the LAN network.

Thanks to this, practically any PC equipped with a network card which operates under Windows 98/2000/XP, can be used.

Documentation:

MT-3 DTR

MT-3 DOU

Winding resistance measurements report	The possibility of comparing OLTC switching times by directly placing them on each other makes assessing changes of technical condition easier	The table of measurement results with deviations of average values allow a quicker evaluation of transformer's technical condition during carrying out test and a faster printout of the measurement report	Comparison of the oscillographic waveforms of the OLTC head switching times

MT-1	MT-2	MT-3

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