Milliohmmeter MIKO-8M(A) new version

• Windings of power and measurement transformers, windings of electric motors, generators, linear compensators and windings of other high-inductance equipment;
• Contacts of circuit breakers, resistors, buses and other inductance-free circuits;
• Selector contacts of OLTC devices,  of earthing devices, disconnecting switches and of other detachable and non-detachable contacts;

The device integrates special-purpose modes for measuring different objects with account of their specific features: resistive and inductance objects; voltage transformers; current and power transformers; generators, motors, compensators, connection filters, and magnets.

High precision of measurements both in laboratory environment and at substations under industrial noises is achieved owing to calculation and setting (for any resistance) of specific maximum possible test current limited by effective power of the device only. Therefore, ratio between a valid signal to winding resistance and the noise amplitude remains high at any resistance.

The archive of measurements available in the device allows review, copy or deletion of test results stored in the self-powered memory of the device (up to 1000 measurements), as well as for supporting the following computations:

• Automatic calculation of relative deviation of winding resistance at three phases against each other;
• Automatic recalculation of linear resistance of windings, connected with delta or star connection to the phase winding resistance;
• Automatic recalculation of resistance at current temperature to the resistance at certified temperature (with due regard to winding material);
• Automatic calculation of deviations measured and normalized to the certified temperature of winding resistance in relation to the certified values of resistances;
• Automatic calculation of winding temperature based on its measured and certified value of resistance and certified temperature.

РOLTC "in-place" check mode allows carrying out of in-place check and diagnostics of OLTC with current-limiting resistors without removing the contactor tank covers. This mode involves measuring of instantaneous current passing at first through the transformer cover and then through OLTC contracts at switching from one tap to another.

A graph of current variance at contacts switching is drawn up and the time of switching as well as the general technical condition of the instrument is checked on its basis. Analysis of the acquired graphs provides not only for sorting out of elements by fault-free/faulty criteria but also for defining the nature of the defect allowing eliminating of fault-free OLTCs opening.

Measurements in milliohmeter mode and in in-place check mode complement each other and provide a comprehensive picture of the state of transformer.

• exceeding of measuring current;
• electromotive force (emf) of self-induction.

At disconnection of the measuring cable from transformer bushings or from the instrument as well as at disconnection of the mains cable from the mains in the course of measurement, emf of self-induction of up to several kV is generated in the disconnected circuit and the electric arc appears in the break point.

MIKO-8М is characterized by the redundant protection against emf of self-induction in case of involuntary disconnection of the measuring cable or power cable protecting users from electric shock and the instrument from being damaged.

• a set of required protective means against superheat of the measuring unit;
  
• protection grounding contact in the mains plug and safety earthing terminal on the case of the measuring unit.
  

Color graphic display of high brightness ensures easy reading on a sunny day, whereas intuitively understandable interface with a sensor display facilitates the instrument use.

The Instrument can be manipulated either from the film keyboard or from the sensor display, as suits..

Personal computer connection through USB or Bluetooth allows for:

• Controlling the instrument with the help of PC;
• Systematizing and storing the results on computer;
• Drawing up of measurement reports

Data transmission to the computer and filing of measurement results is performed with the help of a special program developed by the manufacturer.

Cables of different length and the grip of alligator type clamps allowing performance of ground measurement as well as the measurement from the cover of transformers of all voltage types.

For customer’s choice the MIKO-8M milliohmmeter has two modifications: with an in-built battery (MIKO-8MA) and without an in-built battery (MIKO-8M). The device can also be powered from the mains (≃ 110÷220, 330V).