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A Comprehensive Guide to Troubleshooting and Resolving Common Switchgear Faults (Tripping, Heating)

Release time:

2025-12-02

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Abstract

As a core component in power systems, switchgear undertakes critical tasks such as power distribution, control, and protection. However, due to multiple factors—including design flaws, environmental influences, and improper operation and maintenance—switchgear frequently experiences faults such as tripping and overheating. Such faults can, at best, lead to equipment downtime, but at worst, may result in fires or explosions. This article, drawing on real-world case studies and industry experience, systematically organizes troubleshooting methods and solutions for switchgear tripping and overheating, providing operational and maintenance personnel with a practical guide.

I. Troubleshooting and Resolving Trip Faults

Tripping is the most common protective action in switchgear, typically triggered by overcurrent, instantaneous trip, gas, or temperature protection. The core troubleshooting logic is to “first identify the type of protection and then pinpoint the fault location.”

1. Overcurrent tripping: a typical manifestation of overload.

When the line load exceeds the rated current of the switchgear, the overcurrent relay trips, causing a circuit breaker to trip. For example, in a certain factory, because newly added equipment was not synchronized with an upgrade of the distribution system, the 10kV incoming feeder cabinet experienced frequent tripping. During troubleshooting, the following areas should be given particular attention:

Is the load current continuously exceeding the switch’s rated value (historical data can be obtained via an ammeter or monitoring system)?

Is there a short circuit or ground fault on the line? (Use a multimeter to measure the resistance between phases and to ground; the resistance value should be close to infinity.)

Solution:

Adjust load distribution to avoid overloading any single line.

Replace the switchgear or circuit breaker with one rated for a higher current;

Check the insulation performance of the wiring and repair any aged or damaged cables.

2. Fast-trip tripping: Emergency response to short-circuit faults

Fast-trip protection is used to quickly disconnect severe short-circuit faults; its operating time is typically less than 0.1 second. At a certain substation, a phase-to-phase short circuit was triggered by loose busbar bolts, causing the fast-trip protection to operate. The troubleshooting steps are as follows:

Check busbars, transformers, and line connection points for signs of burning or corrosion.

Use an insulation resistance tester to measure the phase-to-phase insulation resistance. If the reading is below 0.5 MΩ, further inspection is required.

Confirm whether components such as surge arresters and current transformers inside the switchgear are damaged.

Solution:

Tighten all connecting bolts and ensure that the contact surfaces are smooth and free of oxidation.

Replace damaged insulating parts or components;

Isolate the short-circuit point and, after restoring power, step up inspection efforts.

3. Gas and Temperature Protection: Early Warning for Internal Equipment Faults

Gas protection is used for internal transformer faults (such as turn-to-turn short circuits and core overheating), while temperature protection is designed to address equipment overheating. At a certain substation, a severe gas trip occurred due to internal insulation damage in the transformer, causing a total power outage across the entire station. During troubleshooting, the following steps are required:

Check the transformer oil level, oil color, and gas relay operation signals.

Measure the DC resistance of transformer windings to determine whether there are turn-to-turn short circuits.

Confirm whether the setpoints of the temperature sensor and protective devices are reasonable.

Solution:

Perform core lifting inspection and maintenance on the transformer, and replace damaged insulating components.

Adjust the temperature protection setpoint to prevent false operations.

Strengthen transformer ventilation and heat dissipation to reduce operating temperature.

II. Troubleshooting and Resolving Heating Faults

Fever is a “silent killer” in the long-term operation of switchgear, primarily caused by poor contact, design defects, or environmental factors. Its troubleshooting requires a combination of methods such as infrared temperature measurement and contact resistance testing.

1. Poor Contact: The Core Cause of Heating

Poor contact can lead to increased local resistance, which in turn causes overheating. At a certain 110kV substation, the handcart contacts failed to fully insert, causing their temperature to rise to 120℃ and triggering insulation aging. During troubleshooting, the following steps are required:

Use an infrared thermometer to scan the critical parts of the switchgear (such as contacts and busbar connections), and record any points with abnormal temperatures.

Measure the contact resistance; if it exceeds the manufacturer’s specified value (typically ≤50 μΩ), it must be addressed.

Check whether the contact spring pressure is sufficient to ensure tight contact between the moving and stationary contacts.

Solution:

Tighten all connecting bolts and apply conductive paste to reduce contact resistance.

Replace aged or deformed contact springs;

Grind the contact surface to remove the oxide layer.

2. Design Flaw: The Root Cause of Insufficient Heat Dissipation

Some switchgear units experience heat buildup due to their compact structure or inadequate thermal design. For example, a certain KYN28-type switchgear unit, lacking an installed ventilation fan, can reach an internal temperature as high as 60℃ during summer. When troubleshooting, the following steps are required:

- Check the cabinet’s sealing and repair any air leaks;

Confirm whether the cooling fan is operating normally.

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Hunan Chengyuan Electrical CO.,LTD

A Comprehensive Guide to Troubleshooting and Resolving Common Switchgear Faults (Tripping, Heating)