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Emergency Treatment for Odor and Smoke of Drawer-Type Switchgear

source：Zhejiang CHBEST Power Technology Co., Ltd. Addtime：2026-02-25 Views：

Drawer-type low-voltage switchgear is widely used in industrial plants, commercial buildings, power stations, and other fields due to its advantages of flexible configuration, convenient maintenance, and safe operation. It realizes the independent installation, withdrawal, and maintenance of functional units through the drawer structure, ensuring the continuity of power supply for the whole system. However, in the long-term operation process, affected by factors such as equipment aging, improper operation, poor contact, overload, and environmental factors, the drawer-type switchgear may have abnormal phenomena such as odor and smoke. Once these phenomena occur, if not handled in a timely and standardized manner, it is very likely to develop into serious accidents such as short circuits, fires, and equipment explosions, endangering the safety of personnel and property, and causing huge economic losses.

Odor and smoke in drawer-type switchgear are typical early warning signals of electrical faults, which usually indicate that internal components are overheating, insulating materials are aging or burning, or poor contact causes arcing. The key to emergency treatment is to quickly identify the danger level, cut off the power source safely, take effective disposal measures to control the development of faults, and minimize the impact of faults. This article systematically elaborates on the emergency treatment process, common causes, key operation points, and post-disposal measures of odor and smoke in drawer-type switchgear, based on relevant international electrical safety standards (such as IEC 61439, NFPA 70) and on-site operation experience, providing a standardized and operable technical guide for electrical operators, maintenance personnel, and safety managers.

I. Pre-Emergency Preparation and Risk Assessment

Before carrying out emergency disposal, it is necessary to make full preparations and conduct rapid risk assessment to ensure the safety of operators and avoid secondary accidents. The pre-emergency work is the premise of standardized disposal, which directly determines the effectiveness and safety of emergency treatment.

1. Pre-Emergency Preparation

Electrical operation and maintenance units should establish a complete emergency response mechanism for drawer-type switchgear faults, and do a good job in daily preparation to ensure that they can respond quickly when abnormalities occur.

Emergency Equipment Preparation: Equip special emergency tools and equipment near the switchgear, including insulated gloves, insulated boots, insulated pliers, circuit breaker operation handles, fire extinguishers (dry powder, carbon dioxide, or clean agent fire extinguishers, prohibiting the use of water or foam fire extinguishers), smoke detectors, temperature detectors, gas masks, and first-aid kits. All emergency equipment should be regularly inspected and maintained to ensure that they are in good usable condition, and the inspection records should be kept properly.
Personnel Preparation: The operators and maintenance personnel engaged in emergency disposal must hold valid electrical operation certificates, be familiar with the structure, working principle, and operation procedures of drawer-type switchgear, and receive professional emergency training, including fault identification, power cut operation, fire extinguishing skills, and first-aid knowledge. It is strictly prohibited for untrained personnel to carry out emergency disposal operations.
Document Preparation: Keep the complete technical data of the switchgear on site, including the wiring diagram, component parameters, installation and maintenance manual, and emergency disposal plan. The emergency disposal plan should clearly specify the division of responsibilities, operation steps, risk points, and disposal measures to ensure that all personnel can operate in accordance with the plan when an emergency occurs.

2. Rapid Risk Assessment

When odor or smoke is found in the drawer-type switchgear, the operator should first stay away from the switchgear to avoid being injured by possible arcs, explosions, or toxic gases, and then conduct a rapid risk assessment to determine the severity of the fault and the scope of impact. The assessment content mainly includes the following aspects:

Judgment of Smoke and Odor Characteristics: Observe the color and concentration of smoke: light gray smoke is usually caused by overheating of insulating materials; black thick smoke indicates that components are burning seriously; white smoke may be caused by moisture or insulation breakdown. Smell the odor type: burning plastic odor is usually caused by burning of insulating parts such as terminal blocks and cables; burning metal odor indicates that busbars, contacts, or other metal components are overheating or arcing; pungent odor may be caused by the decomposition of insulating materials, which is toxic and harmful.
Observation of Equipment Status: Check whether the switchgear has obvious signs of burning, deformation, or sparking; observe whether the indicator lights, instruments, and other components work normally; listen to whether there are abnormal sounds such as buzzing, cracking, or explosion inside the switchgear. If sparks, open flames, or severe deformation are found, it indicates that the fault is serious and needs to be disposed of urgently.
Scope of Impact Assessment: Determine whether the fault is limited to a single drawer unit or spreads to the entire switchgear; check whether the power supply of the surrounding equipment is affected; evaluate whether the fault may cause fire, power outage, or other secondary accidents, and whether it endangers the safety of on-site personnel.

II. Standard Emergency Treatment Process

The emergency treatment of drawer-type switchgear odor and smoke should follow the principle of "safety first, rapid response, standardized operation, and prevention of expansion", and strictly implement the following steps to ensure that the fault is controlled in the shortest time.

1. Step 1: Alarm and Evacuation

Once odor or smoke is found in the switchgear, the operator should immediately take the following actions:

Sound the Alarm: Press the on-site emergency alarm button immediately to notify the on-site safety management personnel, operation and maintenance personnel, and fire control department of the fault. At the same time, report the fault situation to the superior management department in a timely manner, including the location of the switchgear, the phenomenon of the fault, the severity of the fault, and the on-site situation.
Personnel Evacuation: Organize all irrelevant personnel to evacuate from the fault area quickly, and set up a warning line around the switchgear to prohibit irrelevant personnel from entering. The evacuation route should be pre-determined to avoid crowding and stampede. Operators and maintenance personnel who participate in emergency disposal should wear personal protective equipment (insulated gloves, insulated boots, gas masks) before entering the fault area.

2. Step 2: Safe Power Cut

Cutting off the power source is the core step to prevent the fault from expanding. The power cut operation must be standardized to avoid electric shock, arc flash, or other accidents. The specific operation steps are as follows:

Determine the Power Cut Scope: According to the fault situation, determine whether to cut off the power supply of the entire switchgear or only the faulty drawer unit. If the fault is limited to a single drawer unit (such as only one drawer has smoke and odor, and other drawers are normal), the power supply of the faulty drawer can be cut off first; if the fault spreads to the entire switchgear (such as multiple drawers have smoke, or the main busbar is overheating), the total power supply of the switchgear must be cut off immediately.
Standard Power Cut Operation: For the faulty drawer unit, first pull out the drawer handle to switch the drawer to the "test" position, then turn off the circuit breaker of the drawer unit, and finally pull out the drawer to the "separation" position to completely disconnect the power supply of the faulty unit. For the total power cut of the switchgear, first turn off the main circuit breaker of the switchgear, then pull down the main isolating switch, and hang the "No Switching On, Fault Handling" warning sign on the operation handle to prevent misoperation.
Power Cut Verification: After the power cut operation is completed, use a test pencil or a multimeter to verify that the power supply of the faulty area has been completely cut off, and confirm that there is no residual voltage before proceeding to the next step of disposal. It is strictly prohibited to carry out subsequent operations without power cut verification.

3. Step 3: Fault Isolation and Initial Disposal

After the power supply is cut off, the faulty drawer unit should be isolated in time, and initial disposal should be carried out according to the fault situation to prevent the fault from reoccurring or spreading.

Faulty Drawer Isolation: Pull the faulty drawer completely out of the switchgear cabinet and place it in a safe, well-ventilated area away from flammable and explosive materials. During the pulling process, avoid collision and vibration to prevent the spread of burning components or toxic gases. If the drawer is stuck and cannot be pulled out, do not force it to avoid causing secondary damage; instead, take fire extinguishing measures first and then handle it after the temperature drops.
Initial Disposal Measures: If there is smoke but no open flame, open the ventilation equipment of the switchgear cabinet to accelerate the discharge of smoke and toxic gases, and use a fan to blow air to reduce the temperature inside the cabinet. If there is an open flame, immediately use a dry powder, carbon dioxide, or clean agent fire extinguisher to put out the fire. When putting out the fire, stand at the upwind direction of the fire source, hold the fire extinguisher vertically, aim at the root of the flame, and spray evenly until the fire is completely extinguished. It is strictly prohibited to use water or foam fire extinguishers to put out electrical fires, so as to avoid electric shock accidents.
Toxic Gas Treatment: If the smoke contains pungent and toxic gases, operators must wear gas masks when operating. After the fire is extinguished, continue to ventilate the area for at least 30 minutes to ensure that the toxic gases are completely discharged before entering the area for subsequent inspection.

4. Step 4: Fault Inspection and Cause Analysis

After the fault is initially controlled, it is necessary to conduct a detailed inspection of the faulty drawer unit and the switchgear to find out the root cause of the odor and smoke, so as to avoid the reoccurrence of the fault after the equipment is put into operation again. The inspection should be carried out in accordance with the principle of "from outside to inside, from simple to complex".

External Inspection: First, check the external condition of the faulty drawer unit, including whether the shell is deformed, burned, or discolored; whether the wiring terminals are loose, burned, or corroded; whether the cable insulation layer is damaged, aging, or burned; whether the drawer’s guide rail, locking mechanism, and other components are normal.
Internal Inspection: After the external inspection is completed, open the cover of the faulty drawer unit (only after confirming that there is no residual voltage and no hidden danger of fire) to check the internal components. Focus on checking the circuit breaker, contactor, relay, fuse, busbar, and other components: whether the contacts are burned, oxidized, or poorly contacted; whether the coil of the contactor is burned; whether the fuse is blown; whether the busbar is overheated, deformed, or short-circuited; whether the insulating materials (such as insulating boards, terminal blocks) are aging, charred, or decomposed.
Cause Analysis: Based on the inspection results, analyze the root cause of the odor and smoke. Common causes include: poor contact of contacts (caused by loose terminals, oxidation, or dust accumulation), leading to local overheating and burning; overload or short circuit of the circuit, causing the components to overheat; aging, moisture, or damage of insulating materials, leading to insulation breakdown and arcing; improper operation (such as incorrect drawer insertion, forced closing of faulty components), causing mechanical failure and electrical faults; environmental factors (such as high temperature, humidity, dust, or corrosive gases), accelerating component aging and failure.

5. Step 5: Fault Disposal and Equipment Restoration

After finding out the root cause of the fault, targeted disposal measures should be taken to repair or replace the faulty components, and the equipment should be restored after passing the test to ensure that it can operate safely and stably.

Faulty Component Disposal: For burned, damaged, or aging components (such as contactors, circuit breakers, fuses, and cables), they must be replaced with new components of the same model and parameters to ensure the matching and reliability of the components. For components with poor contact, the contacts should be cleaned (using fine sandpaper or contact cleaner) to remove oxidation and dust, and then tightened to ensure good contact. For damaged insulating materials, they should be replaced in time to restore the insulation performance.
Cleaning and Inspection: After replacing the faulty components, clean the inside and outside of the drawer unit and the switchgear cabinet to remove dust, charred debris, and other impurities. Check the wiring again to ensure that the wiring is correct, firm, and in line with the specifications. Check the insulation performance of the switchgear using a megohmmeter to ensure that the insulation resistance meets the standard requirements (not less than 100MΩ at room temperature).
Test Run and Restoration: After the disposal and inspection are completed, first conduct a no-load test run: insert the drawer unit into the "test" position, turn on the power supply, and check whether the components work normally, whether there is abnormal odor, smoke, or noise. After the no-load test run is normal, switch the drawer to the "working" position, conduct a load test run, and monitor the temperature, current, voltage, and other parameters of the components. Only after the test run is completely normal can the equipment be officially put into operation.

III. Common Causes of Odor and Smoke in Drawer-Type Switchgear

To better prevent and handle the odor and smoke faults of drawer-type switchgear, it is necessary to have a clear understanding of the common causes of such faults. According to on-site operation experience and fault statistics, the common causes can be divided into the following categories:

1. Electrical Contact Faults

Electrical contact faults are the most common cause of odor and smoke in drawer-type switchgear, accounting for more than 60% of all faults. Due to the frequent insertion and withdrawal of the drawer unit, the contacts are easy to loose, oxidize, or accumulate dust, leading to increased contact resistance. When current passes through, local overheating occurs, which burns the contacts and insulating materials, producing odor and smoke. Common contact faults include: loose wiring terminals, oxidized contacts of contactors and circuit breakers, poor contact of drawer plug-in contacts, and dust accumulation on contacts.

2. Overload and Short Circuit

Overload and short circuit are serious electrical faults that can easily cause smoke and fire. Overload refers to the situation where the actual operating current of the circuit exceeds the rated current of the components for a long time, leading to overheating of the cables, busbars, and components. Short circuit refers to the direct connection between the live wire and the neutral wire or the ground wire, resulting in a large short-circuit current, which causes the components to burn instantly. Common causes of overload and short circuit include: improper selection of components (rated current is too small), excessive load of the circuit, damage to the cable insulation layer, and wrong wiring.

3. Component Aging and Damage

With the extension of the service life of the switchgear, internal components (such as contactors, relays, insulating materials, and cables) will gradually age and damage, leading to faults. For example, the coil of the contactor is aging and burned, the insulating board is aging and brittle, the cable insulation layer is cracked and damaged, etc. These problems will cause insulation breakdown, arcing, or overheating, producing odor and smoke. In addition, poor quality components or improper installation will also accelerate component aging and damage.

4. Improper Operation and Maintenance

Improper operation and lack of regular maintenance are important factors leading to odor and smoke faults. Common improper operations include: forced insertion or withdrawal of the drawer unit when the power is not cut off, incorrect closing of the circuit breaker, and random modification of the wiring. Lack of regular maintenance will lead to dust accumulation, contact oxidation, component loosening, and other problems, which cannot be found and handled in time, and gradually develop into serious faults.

5. Environmental Factors

The operating environment of the switchgear has a great impact on its service life and fault rate. In high-temperature, high-humidity, dusty, or corrosive gas environments, the insulation performance of the switchgear will be reduced, components will be corroded and aging accelerated, and contact faults will easily occur. For example, in humid environments, moisture will enter the switchgear, causing insulation breakdown and arcing; in dusty environments, dust will accumulate on contacts, leading to poor contact and overheating.

IV. Preventive Measures and Daily Maintenance

The occurrence of odor and smoke faults in drawer-type switchgear can be effectively prevented through standardized daily maintenance and scientific management. Preventive measures are more important than emergency disposal, which can reduce the occurrence of faults, extend the service life of equipment, and ensure the safe and stable operation of the power distribution system.

1. Regular Inspection and Maintenance

Establish a regular inspection and maintenance system for drawer-type switchgear, and conduct comprehensive inspection and maintenance according to the frequency of use and operating environment of the equipment. The maintenance cycle can be set as monthly, quarterly, and annually, and the maintenance content should include the following aspects:

Daily Inspection: Check whether the switchgear has abnormal odor, noise, or temperature; observe whether the indicator lights and instruments work normally; check whether the drawer unit is inserted in place and whether the locking mechanism is firm.
Monthly Inspection: Clean the inside and outside of the switchgear to remove dust and debris; check the tightness of the wiring terminals and contacts, and re-tighten if loose; check the insulation condition of the cables and insulating materials; test the operation of the circuit breaker, contactor, and other components.
Quarterly and Annual Maintenance: Conduct a comprehensive inspection of all components, replace aging, damaged, or expired components; test the insulation performance and short-circuit withstand capacity of the switchgear; check the drawer’s guide rail, plug-in contacts, and other mechanical components, and lubricate and adjust them if necessary; conduct a load test to ensure that the equipment operates normally under rated load.

2. Standard Operation Specifications

Formulate strict operation specifications for drawer-type switchgear, and require operators to operate in accordance with the specifications to avoid faults caused by improper operation:

Before operating the switchgear, wear personal protective equipment such as insulated gloves and insulated boots, and verify the power supply status.
When inserting or withdrawing the drawer unit, operate gently and smoothly, and ensure that the drawer is inserted in place and locked firmly; it is strictly prohibited to force insertion or withdrawal when the power is not cut off.
When closing or opening the circuit breaker, operate in accordance with the specified sequence to avoid arc flash accidents.
It is strictly prohibited to randomly modify the wiring, replace components of non-matching models, or overload the circuit.

3. Environmental Improvement

Optimize the operating environment of the switchgear to reduce the impact of environmental factors on the equipment:

Install the switchgear in a dry, well-ventilated, and clean area, away from water sources, flammable and explosive materials, and corrosive gases.
For switchgear installed in high-temperature environments, install cooling equipment such as fans or air conditioners to control the ambient temperature within the range of -5℃ to 40℃.
For switchgear installed in high-humidity environments, install dehumidification devices to maintain the relative humidity below 70% to prevent moisture from entering the equipment.
Regularly clean the surrounding environment of the switchgear to avoid dust accumulation.

4. Personnel Training and Management

Strengthen the training and management of electrical operators and maintenance personnel to improve their professional quality and emergency response capabilities:

Carry out regular professional training, including the structure and working principle of the switchgear, operation specifications, fault identification, emergency disposal, and fire extinguishing skills.
Establish a post responsibility system, clarify the responsibilities of each personnel, and conduct regular assessment to ensure that the personnel can perform their duties effectively.
Organize regular emergency drills to simulate the odor and smoke faults of the switchgear, so that the personnel can be familiar with the emergency disposal process and improve the emergency response speed and disposal ability.

V. Conclusion

The odor and smoke of drawer-type switchgear are serious early warning signals of electrical faults, which are related to the safety of personnel and property and the stable operation of the power distribution system. The emergency treatment of such faults must follow the principles of safety first, rapid response, standardized operation, and prevention of expansion, and strictly implement the steps of alarm and evacuation, safe power cut, fault isolation, fault inspection, and equipment restoration to minimize the impact of faults.

At the same time, it is necessary to deeply understand the common causes of odor and smoke faults, and take targeted preventive measures, including regular inspection and maintenance, standardized operation, environmental improvement, and personnel training. Through scientific management and standardized operation, the occurrence of faults can be effectively reduced, the service life of the switchgear can be extended, and a safe and reliable operating environment can be provided for the power distribution system.

With the continuous development of industrial technology, the drawer-type switchgear is developing towards intelligence and automation. In the future, it is necessary to further improve the fault monitoring and early warning system, install intelligent monitoring equipment (such as temperature sensors, smoke sensors, and contact resistance monitors) to realize real-time monitoring of the operating status of the switchgear, find potential faults in time, and realize the transformation from passive emergency disposal to active prevention, providing a more reliable guarantee for the safe operation of the power distribution system.

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