To ensure the safety and reliability of these cables. It is essential to adhere to specific test standards and methods for cable manufacturers to do a factory acceptance tester. We will explore the test standards and methods for low-voltage cables.
Main test standards
First and foremost, it is essential to understand the test standards commonly used for low-voltage cables.
International standards
1. IEC 60502: Applicable to power cables with rated voltages from 1kV to 30kV, it covers requirements such as insulation thickness, conductor resistance, and withstand voltage tests.
2. IEC 60227: For polyvinyl chloride insulated cables with voltages of 450/750V and below, it stipulates requirements such as conductor continuity and insulation mechanical properties.
3. IEEE 400: Field Testing Guide for Power Cables, Emphasizing DC Voltage Testing and Dielectric Loss Factor Measurement
Main testing method
When it comes to testing low-voltage cables, there are several key methods that are typically employed.
1. Insulation Resistance Test
Method: Use an ohmmeter (500V or 1000V range) to measure the resistance between the conductor and the shielding layer (≥ 100 MΩ·km).
Standard: According to GB/T 3048.5-2007, the test time is 1 minute, and environmental temperature correction is required.
2. Withstand Voltage Test
Power Frequency Withstand Voltage: Apply 2.5U₀ + 2kV (U₀ is the rated voltage) for 5 minutes without breakdown (as per GB/T 3048.8).
DC Withstand Voltage: Suitable for old cables, with a voltage of 4 to 6 times U₀, but it may accelerate insulation aging and should be used with caution.
3. Partial discharge (applicable to medium and high voltage cables): Apply a voltage of 1.5U₀, and the discharge amount should be ≤ 10pC (IEC 60885-3).