Measure Solar PV System Insulation Resistance Safely and Accurately While Generating.
Maximum 5kV Test Voltage - Up to 10 TΩ of Insulation Resistance Testing.


The IR5051 is a compact, lightweight, high-voltage insulation resistance tester capable of outputting up to 5 kV. Its unique measurement technology enables stable measurements of up to 10 TΩ. In addition, the IR5051 is capable of testing the insulation resistance of solar PV systems during power generation, and has a CAT III 2000 V safety rating to allow testing of 2000 V PV systems.

Dedicated Measurement Function
In addition to a normal insulation resistance measurement mode, the IR5051 also features a specialized mode for measuring PV insulation resistance.
Flexible Voltage Range
Effectively measures 1500 V solar PV systems and is prepared to accommodate systems up to 2000 V as technology advances.
Standards Compliance
Complies with IEC 62446-1 for Category 1 and Category 2 tests, ensuring robust safety and performance

Key Features

  • Measure solar PV system insulation resistance safely and accurately while generating
  • Measure insulation of high-voltage equipment (such as transformers, cables, and motors)
  • Wide testing voltage range, up to 5000 V from 250 V DC
  • Wide measurement insulation range, up to 10 TΩ
  • Automatically calculated and displayed insulation diagnostics (PI, DAR, and DD)
  • Data memory functions increase your work efficiency by eliminating human errors from manual reporting.
  • Selectable Interface Compatibility: Offers both wireless and USB connectivity options.
  • Compact and lightweight, equipped with an IP65-rated carrying case

Model No. (Order Code)

IR5051 Wireless Adapter Z3210 not included
IR5051-90 Bundled with the Wireless Adapter Z3210

2000 V solar power system compatible

Measure insulation resistance while the solar PV system continues to generate

The CAT III 2000 V and CAT IV 1000 V rated IR5051 can measure insulation resistance and open-circuit voltage in solar power systems up to 2000 V safely.

The IR5051 has a PV insulation resistance measurement function. It features the ability to measure even while PV systems are generating power. This means you don’t have to wait until night for measurement or stop power generation.

Identify ground faults in solar power systems using our free app, GENNECT Cross

The CAT III 2000 V and CAT IV 1000 V rated IR5051 can measure insulation resistance and open-circuit voltage in solar power systems up to 2000 V safely.

  • 1.Use the IR5051's dedicated PV insulation function to measure the insulation resistance of solar strings during operation and detect faulty strings.
  • 2.Measure the voltage at the disconnect switch and send it to GENNECT Cross; the software will locate the panel with the ground fault. This IR5051 is capable of safely and accurately measuring voltages up to 2,000 V DC.

Accurate, easy-to-use insulation resistance meter

Intuitive and precise high-voltage insulation testing

Easy-to-use insulation resistance meter with intuitive rotary knob operation.

  • Selectable output voltage with 5 range settings for insulation resistance testing.
  • Adjust the output voltage between 250 V and 5 kV in increments of 10 V or 25 V to accommodate specific testing needs.
  • Automatic AC/DC detection for seamless voltage measurement.

Precision stability in high voltage insulation testing

When the test object has very high resistance, the insulation resistance meter measures minute currents. Because such measurements are sensitive to even minor changes in the environment, the readings can become unstable. The IR5051 reduces environmental influences using shielded wires, and its unique measurement technology enables stable measurements up to 10 TΩ.

Advanced diagnostics and calculations in insulation testing

Tailored measurement methods with advanced insulation diagnostic functions

When a high test voltage is continuously applied to the circuit under test, the insulation may break down. Failures caused by the application of a high voltage can be prevented by keeping the applied voltage as low as possible while testing the insulation.

The IR5051 is equipped with various insulation diagnostic functions, allowing you to choose the optimal measurement method according to the testing application.

Automatically calculated and displayed insulation diagnostics

After measurement completes, the instrument can display more than just the insulation resistance and leakage current, but also judgement index values of PI, DD, and DAR. It calculates these indexes based on the measured values and displays it as a pass/fail judgment.

Safety engineered

High-Safety design insulation resistance meter

CAT III, CAT IV rated IR5051 hold the highest standards in safety performance. You may think that insulation resistance measurement is not dangerous because it is performed under power outage conditions, but on the contrary, accidents can be dangerous. The IR5051 have enhanced safety performance in case of such an accident.

Start test: Press and hold for 1 sec. to start measurement. This feature helps prevent inadvertent activation of a high voltage.
To encourage caution, the MEASURE button flashes when a high voltage is being generated or discharged.

Complete: The IR5051 will start discharging automatically as soon as the test is over. During this time, the test start button will flash red to indicate that it is discharging.

Wireless and USB connectivity options for even greater convenience

Wireless support(*1)

  • *1:The optional Wireless Adapter Z3210 is required.

Installing the Wireless Adapter Z3210 on the instrument enables Bluetooth® wireless communication, facilitating the transfer of measurements to your smartphone or tablet.

Enhance your insulation resistance meter with GENNECT Cross

  • A time-series graph of the current provides a visualization of the insulation state of a high-voltage cable. Utilize the logging function of GENNECT Cross to generate time-series graphs of data recorded at one-second intervals, enhancing the analysis and understanding of trends.
  • Field Maintenance function: Using a picture of the site, this function can display the measurement values where the measurements are made.
  • Report function: Easily create PDF reports with measurement results.

See here for details about GENNECT Cross

Excel® Direct Input Function

Boost work efficiency in the field by letting you directly transfer measurement data to (i.e., enter measured values directly into) templates created as Excel®.

See details about Wireless Adapter Z3210

Transfer data via USB after measurement

Transfer measured values and logging data saved on the instrument to a PC via USB (*2). This function requires Sequence Maker, a free Excel add-in.

See details about Sequence Maker

  • *2:DMM Communicator DT4900-01 is required (sold separately).

Rugged protection

Dustproof & waterproof case for outdoor work

The Carrying Case C0212 is a rigid case with IP65 dust and water protection. It provides space for the insulation resistance meter and test leads so that they can be transported easily.

Basic specifications

Accuracy guaranteed: 1 year
Measurement parameters • Insulation resistance
• PV insulation resistance
• Leakage current
• Voltage
• Capacitance (DD function)
Max. rated voltage to terminals 1000 V AC, 2000 V DC
Max. rated voltage to ground 1000 V (CAT IV), 600 V (CAT III)
Operating temperature and humidity range -20°C to 50 °C (*1) (no condensation)
Storage temperature and humidity range -25°C to 65°C (-13°F to 149°F), less than 80% RH (no condensation)
Dustproof/waterproof IP40 (with protector attached, excluding terminals)
Standards EN61010 (safety), EN61326 (EMC), IEC 61557-1, IEC 61557-2 (Insulation resistance tester)
Power supply • LR6 (AA) alkaline battery × 8
• HR6 (AA) nickel-metal hydride (NiMH) rechargeable battery × 8
Continuous operating time (*2) Approx. 5 hours without Z3210 installed; approx. 4 hours with Z3210 installed and using wireless communication
Dimensions and weight 195 mm (7.68 in.) W × 254 mm (10 in.) H × 89 mm (3.50 in.) D, 1.7 kg (59.97 oz.) (including batteries)
Included accessories Test lead L9850-01 ×1, Test lead L9850-02 ×1, Test lead L9850-03 ×1, Alligator clip L9851-01 ×1, Alligator clip L9851-02 ×1, Alligator clip L9851-03 ×1, Test pin set L9852 ×1, Carrying Case C0212 ×1, LR6 Alkaline battery ×8, Instruction manual ×1, Operating precautions ×1, Wireless adapter Z3210(IR5051-90 only)
  • *1:-20°C to 40°C (-4°F to 104°F), less than 80% RH , 40°C to 45°C (104°F to 113°F), less than 60% RH , 45°C to 50°C (113°F to 122°F), less than 50% RH
  • *2:When using alkaline batteries, 5 kV generated, +/- terminals open, backlight off and comparator off


Insulation diagnosis PI, DAR, DD, SV, Ramp, Timer (*3)
Others Battery charge indicator, live circuit indicator, automatic power save, automatic discharge, backlight, buzzer, manual recording, logging recording, temperature and humidity input, elapsed time display, clock, filter, hardware filter, data-hold, system reset, USB communication (only when DT4900-01 is installed), wireless communication (only when Z3210 is installed), comparator, resistance gauge display, switching of insulation diagnosis function, breakdown cut-off, negative voltage notification
  • *3:Only for can be set in the PV insulation resistance function

PV insulation resistance

Test voltage range DC 250 V to 2.00 kV
Test voltage presets 500 V, 1 kV, 1.5 kV
User-set test voltage 250 V to 1 kV: in 10 V increments; 1 kV to 2 kV: in 25 V increments
Test voltage preset 500 V 1000 V 1500 V
Guaranteed accuracy range (1) 0.00 MΩ to 5.00 GΩ ±5% rdg ±5 dgt 0.00 MΩ to 10.00 GΩ ±5% rdg ±5 dgt 0.00 MΩ to 20.0 GΩ ±5% rdg ±5 dgt
Guaranteed accuracy range (2) 5.01 GΩ to 100 GΩ ±20% rdg 10.1 GΩ to 100 GΩ ±20% rdg 20.1 GΩ to 100 GΩ ±20% rdg
Rated current [Test voltage] / [20 MΩ]
Open-circuit voltage From 0% to 10% of test voltage
Short-circuit current 2 mA or less
Possible number of measurements 1000 times or more on one set of fully-charged batteries

Insulation resistance measurement

Test voltage range DC 250 V to 5.20 kV DC
User-set test voltage 250 V to 1 kV: in 10 V increments; 1 kV to 5 kV: in 25 V increments
Test voltage preset 250 V 500 V 1000 V 2500 V 5000 V
Guaranteed accuracy range (1) 0.00 MΩ〜2.50 GΩ ±5% rdg ±5 dgt 0.00 MΩ〜5.00 GΩ ±5% rdg ±5 dgt 0.00 MΩ〜10.0 GΩ ±5% rdg ±5 dgt 0.00 MΩ〜25.0 GΩ ±5% rdg ±5 dgt 0.00 MΩ〜50.0 GΩ ±5% rdg ±5 dgt
Guaranteed accuracy range (2) 2.51 GΩ〜500 GΩ ±20% rdg 5.01 GΩ〜1.00 TΩ ±20% rdg 10.1 GΩ〜2.00 TΩ ±20% rdg 25.1 GΩ〜5.00 TΩ ±20% rdg 50.1 GΩ〜10.00 TΩ ±20% rdg
Rated current 1 mA to 1.2 mA
Short-circuit current 2 mA or less
Possible number of measurements 200 times or more on one set of fully-charged batteries

Leakage current measurement

Measurement range (auto) 10 nA 100 nA 1000 nA 10 μA 100 μA 1 mA
Display range 0.00 nA to 9.99 nA 9.0 nA to 99.9 nA 90 nA to 999 nA 0.90 μA to 9.99 μA 9.0 μA to 99.9 μA 90 μA to 999 μA (*4)
0.90 mA to 3.00 mA (*5)
Resolution 0.01 nA 0.1 nA 1 nA 0.01 μA 0.1 μA *4: 1 μA
*5: 0.01 mA

Voltage measurement

Guaranteed accuracy range 30 V to 1,000 V AC (45 Hz to 65 Hz), ±10 V to ±2,000 V DC
Accuracy ±3% rdg. ±3 dgt.
Input resistance 500 kΩ or more (DC, 45 Hz to 65 Hz)
Overload protection 1100 V AC (1 min., between +/- terminals)
2200 V DC (1 min., between +/- terminals)

Capacitance measurement

Capacitance is automatically measured after insulation resistance measurement is over (not measured if output voltage is 250 V or less)
Accuracy ±10% rdg. ±5 nF (guaranteed accuracy range: 10.0 nF to 25.0 µF)
Measurement range 100 nF 1000 nF 10 μF
Display range 0.0 nF to 99.9 nF 100 nF to 999 nF 1.00 μF to 9.99 μF (*6)
10.0 μF to 25.0 μF
Resolution 0.1 nF 1 nF *6: 0.01 μF
*7: 0.1 μF

Included accessories (9)

Z3210 is included with IR5051-90 only

Test leads (6)

Aligator clips (3)

Test pin set (1)

Carrying case (1)