Reviews

In September 2011 we (Ekibastuz GRES-1) procured a PKV/U3.0 instrument for high-voltage circuit breakers testing.

During operation the instrument demonstrated good performances. It perfectly suits the adjustment of air circuit breakers (VNV-500, VVD-220, VVU-110, and VVG-20) used at Ekibastuz GRES-1 (Ekibastuz Thermal Power plant) as during pre-commissioning tests both discrete and analogue signals should be deenergized. A large number of channels, availability of remote start-up, comparatively small weight and availability of connection circuits for different types of high-voltage circuit breakers facilitate the instrumnet use.

MIKO-1 instrument has been in use in our Company since 2010. The instrument has been used for measuring the transient resistances of switching units (circuit breakers 6-110kV, and 110kV connectors).

In our opinion, the instrument is rather convenient in operation, its main merits include:

• compactness;
• mobility;
• simple manipulation;
• availability of an in-built power source;

Recommendation: that would be advisable to have a charger for the battery.

MIKO-1 instruments have been used by personnel of Southern Electric Networks for more than a year. The instruments are used for measuring the DC resistance of main circuits of circuit breakers at scheduled maintenances and during repaird. They are mainly oil circuit breakers of U-220, MKP-110, C-35, VTD-35, VMUE-35, MKP-35, VMP-10, VK-10, VMG-133, VMP-10 types, and vacuum circuit breakers VVST-35, BB/TEL-10, EVOLIS, and others.

The instrument is convenient in operation; battery capacity ensures several days of operation. The instrument can be operated at low temperatures.

In 2011 the elctrotechnical laboratory performed trial operation of PKR-1 (an instrument for transformer testing), PKV/M7 (an instrument for high-voltage circuit breaker testing), MIKO-2.3 (micromillikiloohmmeter) instruments manufactured by SKB EP. The instruments demonstrated high efficiency and are of great practical value.

The MIKO-2.3 instrument replaces the whole set of diverse devices for measuring both low (e.g., transient resistances of contacts, DC resistance of transformer windings) and high (e.g., shunt resistances of circuit breakers) resistances. Despite that the instrument is simple in operation, compact and has low weight. Its advantage is ability to be powered both from a battery and from a 220 V network. Rapid saturation of windings during DC resistance measurements drastically reduces the period of measurements.

PKR-1 device for transformer testing is worth special mentioning. Northern Railways currently has no specialized instruments for LTC diagnosis and for recording the circular diagram, therefore, this equipment is of special value. The instrument is easy to operate, has a friendly interface, is rather compact and convenient for transportation, measurements do not take much time. Defects were detected in six out of nine tested transformers and their presence was confirmed during repair.

It is used for measuring the DC resistance of transformer windings, for measuring the transient resistances of high-voltage circuit breakers, and for measuring the resistance of metal bonds.

MIKO-2.3 is convenient to use owing to its small size, though rapid battery discharge cause some inconveniences as the device is dependent of the availability of a power network. 950A current produced by the instrument burns the contact and produces reliable data on the transient resistance. Advantage of the instrument is ability to combine potential and current circuits in two clamps, and account of proper resistance of wires included into the kit.

Milliohmmeter mode has a function of automatic conversion of resistance versus temperature difference at the factory and on site.

On the whole MIKO-2.3 considerably reduces the time of measurements and produces reliable and accurate results.