top of page

MD542 500V Handheld Insulation Tester

About the MD542:
The TENTECH MD542 is a smart, microprocessor-controlled, 500 V insulation tester for up to 100 GΩ @ 500 V resistance measuring with selectable test voltages of 100 V, 250 V, and 500 V. Compact, handheld, and battery powered, it is designed for field use with reliable accuracy and safety features.

Operation is simple: connect the leads, switch on, select the test voltage, and press the start button. The tester auto-selects the most suitable scale and displays the measured value digitally. Safety is ensured with fully insulated terminals, a high-voltage presence indicator, and automatic discharge.

It also includes advanced features such as 200 mA continuity range, low resistance measurement, AC/DC voltage measurement up to 400 V, programmable timer, memory hold, and selectable resistance limits for pass-fail testing with acoustic indication. The GUARD terminal further improves accuracy by eliminating leakage current effects.

Key Features

  • Insulation resistance testing up to 100 GΩ

  • Test voltages: 100 V – 250 V – 500 V

  • Short circuit current: 1.5 ± 0.3 mA

  • Guard terminal for improved accuracy

  • Automatic range selection

  • Programmable timer

  • Pass/fail testing with acoustic signal

  • Low resistance and continuity measurement

  • AC/DC voltmeter up to 400 V True RMS

  • Rechargeable NiMH battery

Technical Specifications

Nominal test voltages

  • 100 V – 250 V – 500 V (negative DC voltage)

Resistance measurement range

  • 10 kΩ to 100 GΩ

Short circuit current

  • 1.5 ± 0.3 mA

Test voltage accuracy

  • -0 / +15 % (10 MΩ to open circuit)

Basic accuracy

  • R ≤ 50 GΩ: ± 5 % of reading ± 2 digits

  • R > 50 GΩ: ± 10 % of reading ± 2 digits

Continuity / Low resistance measurement

  • Range: 0.05 Ω to 150 Ω

  • Accuracy: ± 5 % of reading ± 2 digits

  • Test current: up to 200 mA

  • Continuity indicator: activates at R < 5 Ω ± 0.5 Ω

Built-in timer

  • 5 – 10 – 15 – 30 seconds

  • 1 – 2 – 3 – 5 – 10 – 15 minutes

Pass/fail limits

  • 0.2 MΩ up to 900 MΩ

  • 1 GΩ up to 10 GΩ

Voltmeter True RMS

  • Range: 0 – 400 VAC/DC

  • Accuracy: ± 3 % of reading ± 2 digits

Additional features

  • Automatic polarization index

  • Guard terminal

  • Memory hold

  • Overvoltage protection: 600 V

Safety & compliance

  • IEC 61010-1, IEC 61326-1, IEC 61000-4-2, IEC 61000-4-3

Power supply

  • Built-in NiMH battery

  • Autonomy: up to 1000 tests (IEC 61557-2)

  • Charger: 12 V – 2 A external supply

Environmental

  • Operating temperature: -10 °C to 50 °C

  • Storage temperature: -25 °C to 70 °C

  • Humidity: 95 % RH (non-condensing)

Dimensions & weight

  • 102 × 195 × 46 mm (4.01" × 7.68" × 1.81")

  • 0.5 kg (1.1 lb)

Included Accessories

  • 2 Measuring test leads

  • 1 GUARD test lead

  • 1 Power cord

  • 1 Carrying bag

  • 1 Operating instructions

bottom of page