HIOKI IR5051 - Portable high voltage insulation tester with PV function

Key Specifications

The portable high voltage insulation tester IR5051 combines standard insulation resistance measurement with a dedicated PV measurement function for photovoltaic systems. It allows insulation resistance testing on PV systems even during power generation. The instrument offers five insulation test voltage ranges from 250 V to 5 kV and seven insulation resistance ranges from 10 MΩ to 10 TΩ. 

Dedicated PV measurement section

A defining feature of the IR5051 is its physically separate measurement section for PV insulation testing. This dedicated section enables insulation resistance measurements on PV systems with test voltages up to 2000 V and resistance ranges up to 100 GΩ. There is no need to wait until nightfall or interrupt power generation. The IR5051 performs insulation resistance measurements on PV systems during the day and while the system is generating power. Each measurement is completed in just 4 seconds, which is particularly relevant when testing several hundred points across larger PV installations. 

The compact and lightweight design is intended for mobile use in PV installations and other electrical systems. The included hard case protects the instrument against dust and water in IP65 environments. With a maximum rated voltage of 2000 V in measurement category CAT III, the IR5051 is designed for testing PV systems in this classification. After the measurement, the automatic discharge function dissipates residual voltage in the test object. Shielded test leads and the built-in guard circuit reduce interference and support stable measurement conditions, including on large or capacitive test objects. 

Insulation diagnosis beyond PV testing 

In addition to PV insulation testing, the IR5051 can also be used for standard high voltage insulation measurements, for example on cables, motors and transformers. In such applications, insulation resistance values are useful for an initial assessment, but they are not sufficient for evaluating aging, moisture ingress, or contamination in detail. Insulation resistance also varies with temperature, humidity, and the time dependent behavior of the insulating material, so a single measurement has only limited value for condition assessment.

For this reason, the IR5051 includes diagnostic functions for standard insulation testing. Polarization Index evaluates the change in insulation resistance over time and provides information about aging, moisture, and contamination. Dielectric Absorption Ratio follows the same principle with shorter time intervals and is suited to applications in which readings stabilize more quickly. Dielectric Discharge is used to assess multilayer insulation and helps identify degradation within the insulation material. 

In addition, Step Voltage and Ramp tests allow insulation behavior to be evaluated under increasing test voltage, helping to reveal weak points that may not be visible at one fixed test voltage. 

Data storage and documentation 

The IR5051 includes an internal memory function for measurement data and therefore supports documentation oriented test workflows even without a direct connection to an external device. Stored measurement values can be retrieved later for further evaluation or reporting. 

The IR5051 can be expanded with the optional Z3210 Bluetooth adapter. When installed, measurement data can be transferred wirelessly to smartphones or tablets for documentation and further processing. In combination with the free GENNECT Cross app for iOS and Android, this supports documentation oriented test workflows directly in the field. The Z3210 also supports HID mode, allowing measured values to be entered directly into Excel or other applications as keyboard input. 

For PC based documentation workflows, stored measurement data can be transferred to a computer using the optional DT4900-01 communication package. The optically isolated interface provides galvanic separation from the PC and also allows instrument settings to be changed from the computer. Measurement control itself is not supported via DT4900-01. 

The IR5051 is manufactured in HIOKI’s own production facilities in Japan.