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S431 10KV Insulation Test Set

Six DC test voltages from 250 V to 10 kV
Insulation resistance up to 20.0 TΩ at 10 kV, with 0.01 MΩ resolution
IR, PI, DAR, DD, step voltage and ramp test modes
Selectable noise filter and GUARD connection for surface-leakage control
Leakage current during testing and capacitance results after the test
Automatic discharge and auto-save for up to 1,000 test records
USB PC software and Bluetooth app for trends, logging and export

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Product Description

The S431 is a 10 kV insulation resistance tester for maintenance and condition assessment of motors, generators, transformers, cables and switchgear. It provides six DC test-voltage settings from 250 V to 10 kV and measures insulation resistance from 0.01 MΩ up to 20.0 TΩ. The available resistance range and accuracy depend on the selected test voltage.

Timed insulation testing with PI and DAR, dielectric discharge, step voltage and ramp functions helps compare insulation behaviour over time and at different applied voltages. The instrument displays leakage current during an insulation test and capacitance after completion, with separate external AC/DC voltage measurement up to 1000 V. Stored records, USB PC software and a Bluetooth app support trend review and data export.

Technical FAQ

How does the S431 differ from the S430?

The S431 provides a 10 kV DC setting and measures up to 20.0 TΩ at 10 kV. The S430 provides up to 5 kV and 10.0 TΩ, and includes a 100 V setting that the S431 does not provide. Both models document PI, DAR, DD, step voltage, ramp, automatic discharge, filtering, storage and connectivity.

What test voltages and resistance range does the S431 provide?

The S431 provides 250 V, 500 V, 1 kV, 2.5 kV, 5 kV and 10 kV DC settings. Its overall resistance range is 0.01 MΩ to 20.0 TΩ, with the 20.0 TΩ upper limit available at 10 kV. At 10 kV, 0.01 MΩ to 400 GΩ is specified at ±5% rdg ±5 dgt, and 400 GΩ to 20.0 TΩ at ±20% rdg ±5 dgt. At 250 V to 5 kV, the lower bands are ±3% rdg ±5 dgt and the upper bands ±15% rdg ±5 dgt; the band boundaries depend on test voltage.

How are PI and DAR calculated, and what do they indicate?

The default PI calculation is R10min / R1min. DAR1 is R60s / R15s, and DAR2 is R60s / R30s; the PI timing can also be configured. DAR provides a shorter-term view, while PI is more suitable for large-capacitance assets or insulation with a longer absorption process. PI and DAR are mainly indicators of moisture and contamination and cannot identify every type of insulation defect.

When should the GUARD terminal be used?

Use the GUARD terminal when unwanted surface leakage would distort the resistance of the insulation path being measured. The GUARD connection diverts that leakage current around the sensitive measurement circuit, which is particularly important at very high resistance values. GUARD is not protective earth: the EARTH terminal is the measurement return, and the correct L-E-G connection depends on the asset and the insulation path under test.