How to Perform a Dielectric Strength Test – A Step-by-Step Guide
When it comes to high-voltage equipment, safety and reliability are paramount. Dielectric strength testing — sometimes called a hi-pot test — is one of the most effective ways to ensure electrical insulation can withstand the voltages it will face in the real world.
In this guide, we’ll walk you through the essentials of dielectric strength testing: what it is, why it matters, and how to perform it properly — with a focus on Canadian standards.
🧪 What Is a Dielectric Strength Test?
A dielectric strength test evaluates the maximum voltage that insulating material can withstand without breaking down. It's used to verify that insulation on wires, cables, transformers, and electrical devices can handle expected voltage levels — and more — without leakage or failure.
🛠 What You Need
- A dielectric strength tester (commonly known as a Hi-Pot tester)
- Proper test leads and accessories (ensure they are rated for the voltages being applied)
- Personal protective equipment (PPE) and safety controls
- A controlled test environment with clear procedures and emergency stop access
At Duncan Instruments, we stock trusted brands like Metrel, Tentech, Megabras, Fluke, and AEMC — all with models certified for industrial safety testing.
⚡ Step-by-Step: Performing the Dielectric Strength Test (Canada Edition)
1. Understand the Test Standard
In Canada, the dielectric strength test is typically conducted at:
- 2 × rated operating voltage + 1,000 V for a 60-second test, or
- 10% higher voltage for a 5-second test (i.e., multiply the 60-second voltage by 1.10).
🔍 Examples:
| Operating Voltage | 60-Second Test Voltage | 5-Second Test Voltage (+10%) |
|---|---|---|
| 120 V | 2×120 + 1000 = 1240 V | 1240 × 1.10 = 1364 V |
| 240 V | 2×240 + 1000 = 1480 V | 1480 × 1.10 = 1628 V |
2. Set Up the Device Under Test (DUT)
- Disconnect the DUT from power and discharge capacitors
- Connect the high-voltage lead to the line or conductor
- Connect the return lead to ground or chassis
3. Configure the Tester
- Set the correct test voltage (per standard above)
- Set the hold time (60 sec or 5 sec) and leakage current limit
4. Perform the Test
- Start the test — voltage ramps up to target level
- Hold steady for the specified time
- Monitor for current leakage or breakdown
5. Evaluate the Results
- Pass: No breakdown, current below limit
- Fail: Breakdown occurs (audible arc, tester trips), investigate cause
6. Discharge and Document
- Always discharge the DUT after test
- Record: voltage applied, duration, leakage current, result, and technician name
✅ Best Practices
- Never touch test leads or DUT during the test
- Use equipment with interlocks and visual indicators
- Repeat the test if the device was repaired or exposed to extreme conditions
- Ensure records are stored for compliance tracking
🧰 Trusted Testers, In Stock Now
During the recent global shortage, Duncan Instruments was proud to remain a reliable source for dielectric strength testers in Canada. Whether you need a 5 kV portable unit or a 20 kV lab-grade tester, we’ve got you covered — with expert support and fast shipping.
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