Hi-Pot Withstanding Voltage Tester

Withstanding Voltage / Hi-Pot Tester for Electrical Safety Testing - TOB-TH9320 Series

Product Overview and Ideal Applications

The TOB-TH9320 series is a withstanding voltage (hi-pot) and insulation tester family covering three models - TOB-TH9310, TOB-TH9310B, and TOB-TH9320. The instrument performs AC and DC withstanding voltage tests together with insulation resistance tests, and it adds fast discharge and arc detection functions. The TOB-TH9320 is the high-range model of the series: its AC current test range reaches 0 mA - 20.00 mA and its DC current test range reaches 0 µA - 10.00 mA, compared with 0 mA - 10.00 mA (AC) and 0 µA - 5.00 mA (DC) on the TOB-TH9310 / TOB-TH9310B.

The tester is fitted with a 480 x 272 dot TFT-LCD display and a brand-new operation interface with a user-friendly panel design. It can store 20 test files, and each file supports up to 20 test steps - and any step may select any test mode, so a complete safety test sequence (for example an AC withstanding voltage step by a DC step and an insulation resistance step) can be configured as one file and run step by step. Voltage ramp-up time and test time can be set freely up to 999.9 s; for DC withstanding voltage, the test wait time can be set arbitrarily.

For personal safety, the series provides enhanced electric shock protection, and it includes fast discharge and arc detection functions: after a DC withstanding voltage test ends, the instrument discharges automatically, and arc events are monitored during testing within the arc detection corresponding current measurement range of 1 mA - 20 mA. A keyboard lock function prevents unintended parameter changes during production, and the instrument firmware can be upgraded via USB flash drive.

For system integration, the tester supports a PLC interface together with the standard RS232, USB HOST, USB DEVICE, SIGNAL, and HANDLER interfaces, and the Modbus protocol is supported - so the instrument can be operated inside automated test systems or run standalone from its stored test files. The unit is compact for bench use: 280 mm x 88 mm x 428 mm, with a net weight of 11 kg (TH9310 series) or 12.3 kg (TH9320 series).

Ideal for:

• Automated test systems that integrate safety testing through the PLC, HANDLER, and RS232 interfaces.
• Safety testing of transformers and motors, electronic components, and electrical equipment.
• Production lines in the lighting industry, the household appliance industry, and the heating appliance industry.
• New energy vehicle electrical components and systems that require withstanding voltage and insulation verification.
• Medical equipment manufacturing, where routine electrical safety testing is part of the production flow.

Need to match the AC or DC test voltage, current range, and interface configuration to your production line? Contact our test equipment engineers with your product and test plan.

Where Hi-Pot Testing Fits in Electrical Safety Testing

Withstanding voltage testing - also called hi-pot testing or dielectric strength testing - is a routine electrical safety test. A specified test voltage (AC or DC) is applied between the current-carrying parts and the accessible conductive parts of a product, or between its primary and secondary circuits, for a defined test time; the instrument monitors the leakage current and judges the result against the configured limit, verifying that the insulation withstands the applied stress. The insulation resistance (IR) test complements this check: a DC voltage is applied and the resistance of the insulation system is measured, which indicates insulation quality as a quantitative value. Arc detection adds a further layer - brief arc events that occur during a test can indicate marginal gaps or creepage paths, and this instrument monitors them within its 1 mA - 20 mA arc detection range.

In production, these tests are typically performed at the end of the line for safety compliance, and also in incoming and outgoing quality control; in laboratories, they are part of type testing and design verification. Because a full test sequence often combines several tests - for example an AC withstanding voltage step, a DC withstanding voltage step, and an insulation resistance step - the way test conditions are stored and repeated matters as much as the measurement itself. This is why the TOB-TH9320 series stores 20 test files, each supporting up to 20 test steps, with any step able to select any test mode: one file can reproduce an entire test sequence for one product type, and the time parameters (voltage ramp-up, test time, voltage fall time, and IR wait time) are set explicitly for each application.

The series fits both standalone benches and automated lines. On a bench, tests are started from the stored files and the results are read from the 480 x 272 dot TFT-LCD display. On an automated line, the PLC interface, HANDLER interface, and RS232 connection carry control and pass/fail signals to the surrounding equipment, and the keyboard lock function keeps the configured parameters secure during production. Firmware can be updated on site via USB flash drive when new functions are released.

Key Engineering Characteristics of the TOB-TH9320 Series

1. AC and DC Withstanding Voltage Testing in One Instrument: The output voltage range is 0.05 kV - 5.00 kV AC and 0.05 kV - 6.00 kV DC, each with an accuracy of ±(2% of reading). The current test range is 0 mA - 20.00 mA (AC, TH9320) or 0 mA - 10.00 mA (AC, TH9310/B), and 0 µA - 10.00 mA (DC, TH9320) or 0 µA - 5.00 mA (DC, TH9310), each with an accuracy of ±(2% of reading + 5 digits).
2. Insulation Resistance Testing up to 10 GΩ: The IR output voltage range is 0.10 kV - 1.00 kV with an accuracy of ±(2% of reading), and the resistance test range is 0.1 MΩ - 10.0 GΩ. The resistance accuracy is ±(10% of reading + 2 digits) over the 0.10 MΩ - 999 MΩ range, and ±(20% of reading + 2 digits) over the 1.00 GΩ - 10.0 GΩ range.
3. Arc Detection with 1 mA - 20 mA Measurement Range: The arc detection function corresponds to a current measurement range of 1 mA - 20 mA, so arc events during a test are identified and reported.
4. 20 Test Files, Each with up to 20 Test Steps: 20 test files can be stored; each file supports up to 20 test steps, and any step may select any test mode - so complete multi-stage test sequences run automatically from one file.
5. Freely Settable Time Parameters up to 999.9 s: voltage ramp-up time and test time can be set freely up to 999.9 s (ramp-up 0.1 s - 999.9 s; test time 0.2 s - 999.9 s; voltage fall time 0.1 s - 999.9 s; IR wait time 0.2 s - 999.9 s). For DC withstanding voltage, the test wait time can be set arbitrarily.
6. Fast Discharge and Enhanced Electric Shock Protection: Fast discharge is provided - automatic discharge after the test ends (DCW) - and the instrument provides enhanced personal safety through electric shock protection. The discharge function of the insulation resistance test is also automatic after the test ends.
7. Automation-Ready Interfaces: Standard interfaces include RS232, USB HOST, USB DEVICE, SIGNAL, HANDLER, and PLC. The PLC interface is supported, and the Modbus protocol is supported for system integration.
8. 480 x 272 Dot TFT-LCD Display and New Operation Interface: The instrument uses a 480 x 272 dot TFT-LCD display with a brand-new operation interface and a user-friendly panel design, making parameter setting and result reading straightforward.
9. USB Firmware Upgrade and Keyboard Lock: The instrument firmware can be upgraded via USB flash drive, so functional updates do not require returning the unit; the keyboard lock function prevents unintended changes to configured parameters.
10. Compact Bench Format: The dimensions are 280 mm x 88 mm x 428 mm (W x H x D). Net weight is 11 kg for the TH9310 series and 12.3 kg for the TH9320 series, so the tester sits easily on a workbench or inside a test rack.

Standard Interfaces and Physical Specifications

Standard interfaces: RS232, USB HOST, USB DEVICE, SIGNAL, HANDLER, PLC.

Note: Modbus protocol is supported.

Physical Specifications

Complete Technical Specifications

1. Withstanding Voltage Test

2. Insulation Resistance Test

3. Arc Detection

4. General Parameters

Note: The specifications in this document are translated from the Chinese product datasheet. In case of any inconsistency, the Chinese version shall prevail.

Standard Accessories

Practical Operating Recommendations

• Prepare one test file per product type before production: the instrument stores 20 test files with up to 20 steps each, and any step may select any test mode - so each product's full test sequence, including AC withstanding voltage, DC withstanding voltage, and insulation resistance steps, runs from a single file.
• Set the test voltage within the rated ranges: 0.05 kV - 5.00 kV (AC) or 0.05 kV - 6.00 kV (DC) for withstanding voltage, and 0.10 kV - 1.00 kV for insulation resistance. Confirm the configured test voltage matches the product standard before starting a run.
• Set the current judgement limits within the instrument ranges: AC 0 mA - 20.00 mA (TH9320) or 0 mA - 10.00 mA (TH9310/B); DC 0 µA - 10.00 mA (TH9320) or 0 µA - 5.00 mA (TH9310). The current measurement accuracy is ±(2% of reading + 5 digits).
• Set the time parameters to match the test standard: voltage ramp-up 0.1 s - 999.9 s, test time 0.2 s - 999.9 s, voltage fall time 0.1 s - 999.9 s, IR wait time 0.2 s - 999.9 s. For DC withstanding voltage, the test wait time can be set arbitrarily as required by the product.
• Use the keyboard lock during production: lock the panel once the parameters are verified, so operators cannot change the stored settings by accident.
• Rely on the automatic discharge: after a DC withstanding voltage test ends, the instrument discharges automatically (fast discharge, DCW); the insulation resistance test also discharges automatically after the test ends. Wait for the discharge indication before handling the sample.
• Keep firmware current: the instrument firmware can be upgraded via USB flash drive; follow the release notes when updating the unit on site.
• Plan the system integration: use the PLC interface, HANDLER interface, and RS232 connection to link the tester with automated lines; the Modbus protocol is supported, and USB DEVICE (PC) and USB HOST (U-disk) connections are standard.
• Use the standard accessories: connect the instrument with the supplied three-core power cord, and carry out tests with the supplied TH90003C and TH90003R withstanding voltage test leads.
• Observe the test area: the instrument provides electric shock protection, but during high-voltage tests the sample area should be treated as a live area until the test has ended and the automatic discharge has completed.

Engineering FAQ

Q1: What is the TOB-TH9320 series? 

The TOB-TH9320 series is a hi-pot and insulation tester family covering three models - TOB-TH9310, TOB-TH9310B, and TOB-TH9320. The instruments perform AC and DC withstanding voltage tests, insulation resistance tests, and arc detection, with fast discharge and enhanced electric shock protection. The TOB-TH9320 is the high-range model of the series.

Q2: What is the difference between the models in the series? 

The main differences specified in the datasheet are the current test ranges and the net weight. The AC current test range is 0 mA - 10.00 mA for the TH9310/B and 0 mA - 20.00 mA for the TH9320; the DC current test range is 0 µA - 5.00 mA for the TH9310 and 0 µA - 10.00 mA for the TH9320. The net weight is 11 kg for the TH9310 series and 12.3 kg for the TH9320 series.

Q3: What are the withstanding voltage output ranges? 

The output voltage range is 0.05 kV - 5.00 kV for AC and 0.05 kV - 6.00 kV for DC, each with an accuracy of ±(2% of reading). The AC current test range is 0 mA - 20.00 mA (TH9320) or 0 mA - 10.00 mA (TH9310/B); the DC current test range is 0 µA - 10.00 mA (TH9320) or 0 µA - 5.00 mA (TH9310). Current accuracy is ±(2% of reading + 5 digits).

Q4: What are the insulation resistance test specifications? 

The IR output voltage range is 0.10 kV - 1.00 kV with an accuracy of ±(2% of reading). The resistance test range is 0.1 MΩ - 10.0 GΩ. The resistance accuracy is ±(10% of reading + 2 digits) over the 0.10 MΩ - 999 MΩ range, and ±(20% of reading + 2 digits) over the 1.00 GΩ - 10.0 GΩ range. The test discharges automatically after it ends.

Q5: What is the arc detection function? 

Arc detection monitors arc events during testing, with a corresponding current measurement range of 1 mA - 20 mA. Together with the fast discharge function - automatic discharge after the test ends (DCW) - it is part of the instrument's protection concept for the operator and the device under test.

Q6: How many test files and steps can be stored? 

20 test files can be stored; each file supports up to 20 test steps, and any step may select any test mode - so a complete multi-stage sequence for one product runs automatically from a single file.

Q7: What time settings are available? 

Voltage ramp-up time and test time can be set freely up to 999.9 s: the voltage ramp-up time range is 0.1 s - 999.9 s, the test time setting (AC/DC) is 0.2 s - 999.9 s, the voltage fall time is 0.1 s - 999.9 s, and the wait time (IR) is 0.2 s - 999.9 s. For DC withstanding voltage, the test wait time can be set arbitrarily.

Q8: What interfaces does the instrument provide, and can the firmware be upgraded? 

The standard interfaces are RS232, USB HOST, USB DEVICE, SIGNAL, HANDLER, and PLC; the PLC interface is supported and the Modbus protocol is supported. For the standard interface list in the general parameters, the interfaces are HANDLER, RS232, USB DEVICE (PC), and USB HOST (U-disk). The instrument firmware can be upgraded via USB flash drive, and a keyboard lock function is provided.

Q9: What safety features are included? 

The series provides enhanced personal safety with electric shock protection, fast discharge and arc detection functions, and automatic discharge after the test ends (DCW for withstanding voltage, and automatic discharge for the insulation resistance test). A keyboard lock function prevents unintended parameter changes, and the instrument firmware can be upgraded via USB flash drive.

Q10: What are the physical specifications and standard accessories? 

The dimensions are 280 mm x 88 mm x 428 mm (W x H x D); the net weight is 11 kg (TH9310 series) and 12.3 kg (TH9320 series). The standard accessories are: 1 three-core power cord, 1 TH90003C withstanding voltage test lead, and 1 TH90003R withstanding voltage test lead.

Ready to add AC/DC withstanding voltage and insulation resistance testing to your production line or laboratory? Request a quotation for the TOB-TH9320 series with your test voltage, current range, and interface requirements, and specify the model within the series that matches your product. Our test equipment engineers can advise on the test file structure, the time parameter settings, and the integration with your automated system.

tob.amy@tobmachine.com| +86 181 2071 5609

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