Insulation resistance tester KEW3125B 250V- 5000V, DAR, PI 105880

Precise Insulation Diagnostics in Electrical Installations

The Kyoritsu KEW3125B insulation resistance meter is a professional measuring instrument designed to assess the condition of insulation in low and medium voltage electrical installations. The device enables acceptance and diagnostic measurements using five test voltages - from 250 V up to 5000 V - allowing the measurement conditions to be matched to the characteristics of the installation under test.

The measurement range for resistance extends to 1 TΩ, and a short-circuit current of approximately 1.5 mA provides sufficient power to break through parasitic surface leakage currents during the test. The manufacturer recommends calibrating the device on a 12-month cycle, which is important information for metrology departments and personnel responsible for maintenance operations.

PI and DAR Indicators - Insulation Condition Assessment Without Raw Result Interpretation

One of the key functions of the KEW3125B is the automatic calculation and display of the PI indicator (Polarization Index - the ratio of resistance after 10 minutes to resistance after 1 minute) and the DAR indicator (Dielectric Absorption Ratio - the ratio of resistance after 60 seconds to resistance after 30 seconds). Both coefficients are presented on the auxiliary display without the need to manually stop a stopwatch or later recalculate results - which significantly speeds up the procedure for assessing the insulation condition of transformers, motors, and cables.

The PI indicator enables the detection of moisture and contaminants in the insulation. A PI value above 4 indicates very good insulation condition; a result between 2 and 4 is acceptable for new equipment; below 2 may indicate a problem requiring intervention. The DAR indicator, on the other hand, provides faster orientation - a result above 1.6 with a measurement lasting just one minute allows a preliminary assessment of insulation quality without the need for a long-duration test.

In addition to insulation resistance measurement, the device also measures DC and AC voltage in the range of 30-600 V, allowing verification of the presence of parasitic voltage before starting the insulation test.

User Functions and Resistance to Field Conditions

The meter is equipped with an anti-interference filter, which stabilizes readings even in environments with strong electromagnetic interference - typical of switchgear rooms and industrial plants. The automatic circuit discharge function with simultaneous voltage monitoring during discharge eliminates the risk of electric shock after completing the high-voltage test.

Notable are the new alligator clip test leads included as standard (straight tip KEW8254), designed for reliable contact with wires and terminals. Optionally available is a 15 m phase lead (KEW7253) with an insulated alligator clip, useful for measuring extensive cable lines or station transformers.

The device signals:

• circuit remaining under voltage,
• measurement range exceeded,
• battery depletion.

At a load of 100 MΩ at a test voltage of 5000 V, battery operation time reaches approximately 25 hours. The large backlit LCD display ensures clear readability of results both in brightly lit technical rooms and in poorly lit switchgear areas. The complete set is delivered in a hard transport case.

Safety and Standards

The KEW3125B meets the requirements of standard PN-EN61010-1,-2,-30 in the classification CAT III 600 V / CAT IV 300 V at pollution degree 2, confirming its suitability for measurements in building installations and at the power supply of end-use equipment. The test leads comply with standard PN-EN61010-031.

The measurement tolerances specified by the manufacturer apply at a temperature of **23