What Are the Signs That Switching Electrical Appliances Have Reached the End of Their Service Life?

What Are the Signs That Switching Electrical Appliances Have Reached the End of Their Service Life?

The end of the service life of switching electrical appliances generally falls into two categories: electrical life and mechanical life.

1. Signs That a Switching Electrical Appliance Has Reached the End of Its Service Life

The end of the electrical life of switching electrical appliances can generally be divided into the following four situations:

• The moving and fixed contacts are completely worn out. This is the primary sign that the service life of a switching electrical appliance has ended. For this reason, electrical life testing is often also referred to as an electrical wear test. Contact wear is usually difficult to detect in advance, but before complete failure occurs, there are often signs that the switchgear can no longer operate normally.
• The contacts are not fully worn out, but the contact overtravel has disappeared, causing the moving and fixed contacts to be nearly non-contacting or in an unstable contact state.
• Contact welding caused by contact wear. Contact welding may lead to serious electrical accidents, so adequate circuit protection must be provided against this phenomenon.
• Damage to the inner wall of the arc extinguishing chamber due to continuous erosion and wear from the high temperature of the arc, resulting in burn-through, cracking, or other damage.

The end of the mechanical life of switching electrical appliances can also generally be divided into the following four situations:

• Fracture or damage of components. This is the most common sign of the end of mechanical life. Once parts break or are damaged, the switching electrical appliance can no longer continue to be used.
• Wear of transmission components such as rotating shafts. When the degree of wear affects operation or performance, the appliance is considered to have reached the end of its service life.
• Loosening of connecting parts. This can be either repairable or non-repairable. However, modern switching electrical appliances are generally designed as maintenance-free structures, so loosening of connecting parts usually means the appliance can no longer continue in service.
• Damage to the electromagnetic operating system. For electrically operated switches such as contactors, failure of the electromagnetic operating system is also one of the common reasons for end of life.

2. Electrical Life Testing and Evaluation of Switching Electrical Appliances

Electrical life testing of switching electrical appliances is generally carried out using dedicated electrical life test equipment. Because electrical life testing has a long cycle, the test equipment is relatively complex, and many factors can affect the results, it is necessary to first confirm that there are no issues with the test equipment or test method before determining whether the sample passes. For example, it must be verified that the main test circuit, program control, and measurement methods all comply with the relevant requirements.

During the test, key parameters such as voltage, current, frequency, power factor, and time constant should be checked regularly to confirm they remain within the specified limits. Only then can the test results be considered reliable.

Evaluation is generally divided into two stages:

• During the test process, if interphase flashover, flashover to ground, contact welding, arc chamber damage, or abnormal operation is found, detailed inspection must be carried out to determine the severity of the problem and identify possible causes.
• Generally speaking, if a failure occurs during the test, it often indicates that the sample’s electrical life has not reached the expected target.
• After the sample has reached the specified number of electrical life cycles, parameters such as insulation and dielectric withstand performance should be checked to determine whether damage has occurred. The operating parameters of the sample should also be measured to determine whether operating performance has changed, and necessary temperature-rise tests should be conducted to confirm the condition of contact engagement.

Only after these complete tests have been carried out can the electrical life be properly judged as qualified or unqualified.

3. Mechanical Life Testing and Evaluation of Switching Electrical Appliances

If a switching electrical appliance is damaged due to component fracture during a mechanical life test, it is generally considered to have reached the end of its mechanical life—unless it can be proven that the damage was caused by an improper test method or an accident.

The causes of the damage should be carefully inspected and analyzed, such as whether the raw material quality was poor or whether the machining and process treatment were improper.

Wear of transmission components or loosening of connecting parts directly affects the reliability of operation. During testing, a certain limited range of unreliable operation may be allowed. When the degree of unreliable operation exceeds the preset allowable range, the mechanical life may be considered to have reached its limit.

Damage to the electric operating mechanism of switching electrical appliances—including cases such as loss of power due to broken wires, inter-turn short circuits caused by insulation breakdown, or burnout due to severe overload—will also render the appliance unusable and indicate the mechanical life limit has been reached.

It should be noted that during mechanical life testing, these electric operating mechanisms are often more vulnerable to damage than under long-term energized conditions. This is because, during mechanical life testing, the operating mechanism is not only energized and heated, but also subjected to frequent switching actions, current and voltage shocks, and mechanical impact. Therefore, the operating frequency used in mechanical life testing should be adjusted appropriately to avoid imposing excessively harsh conditions on the operating mechanism.

4. Electrical and Mechanical Life Test Equipment

As mentioned above, the end of the electrical and mechanical life of switching electrical appliances has different causes and manifestations. To accurately test the electrical and mechanical life of switching electrical products, it is essential to use well-configured test conditions, correct test methods, and fast and accurate test result detection.

For this reason, choosing modern, safe, and reliable test equipment is a necessary condition for conducting electrical and mechanical life testing of switching electrical appliances.

Drawing on nearly twenty years of industry experience, and based on the structure and operating principles of electrical apparatus, we design and manufacture electrical life test equipment and mechanical life test equipment for primary and secondary electrical devices such as:

• AC/DC miniature circuit breakers
• molded case circuit breakers
• contactors
• automatic transfer switches
• isolating switches
• signal relays
• intermediate relays
• push buttons
• limit switches

All equipment is developed in compliance with the latest national standards as well as IEC, UL, and other applicable standards and specifications.

Compared with traditional testing equipment, our products offer the following features:

• Designed and manufactured strictly in accordance with the latest standards, ensuring that test conditions and procedures fully comply with standard requirements. Custom test equipment that exceeds standard requirements can also be provided based on users’ R&D needs.
• All components are rigorously selected and tested, with equipment service life of more than 15 years (since being put into use in 2006), operating cycles exceeding 100,000,000 times, and equipment availability above 99%.
• Modular design, making component maintenance, repair, replacement, and upgrading more convenient. We also provide retrofit, upgrade, and outsourced O&M services for users’ legacy equipment to meet new standards.
• Optional IoT and AI modules, enabling remote equipment monitoring and control, data model analysis, and other functions.
• Long-term after-sales support, including equipment operation and maintenance, spare parts support, and software updates, with support experience already exceeding 15 years, ensuring worry-free equipment use for customers.

In addition to electrical life and mechanical life test equipment, we can also provide:

• synthetic circuit test systems for high- and low-voltage switching electrical appliances
• short-circuit and short-time withstand test systems
• temperature-rise and tripping test equipment
• contact characteristic, overtravel, and contact gap test equipment for contactors, relays, and similar products
• running-in test equipment for switching electrical appliances
• complete design, implementation, and digitalization services for switching electrical appliance testing equipment and laboratories
• automated inspection equipment and systems for switchgear production lines, including assembly, laser marking, packaging, and more

For inquiries: 400-029-9162