Maintenance measures for molded case circuit breakers under high temperature

In the hot summer, the sun is scorching and the temperature is rising sharply. The maintenance of molded case circuit breakers in such an extreme high temperature environment becomes particularly critical. Correct maintenance measures can ensure its stable operation under high temperature, avoid failures, and ensure the safety and stability of the power system.The maintenance steps for molded case circuit breakers in this environment will be thoroughly discussed in this paper to guarantee their performance and dependability as well as the safe and stable running of the power system.

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1. Ambient temperature control:

The molded case circuit breaker’s usual operational ambient temperature ranges from -5℃ to +40℃; the average value for 24 hours falls short of 35℃. The on-site operating current should be lowered as much as feasible or on-site heat dissipation treatment should be carried out to prevent overheating-related circuit breaker loss of overload protection capability in highly high temperature situations.

2. Heat dissipation measures:

In seasons of high temperatures, equipment is prone to breakdown from too high temperatures. Thus, frequent equipment repair and care are absolutely vital. Cleaning, lubrication, fastener inspection and equipment replacement constitute part of maintenance. Cleaning helps to avoid too much dust and contaminants building up on equipment surfaces, therefore reducing poor heat dissipation.

3. Inspection and cleaning:

Check the circuit breaker’s look often to be sure there is no dampness or dust; if so, clean it. The terminal and the house remain unaltered in color. Table 3 shows the torque, hence the terminal connection should be tightened in line with this torque and should not be free.

4. Avoid direct exposure:

Steer clear of putting the circuit breaker in an area straight facing sunlight or a highly heated environment. Should it be used outside, steps should be taken to lessen the direct sunlight’s effects on the circuit breaker.

5. Check the arc extinguishing cover:

Following a fault trip, first look at whether additional parts, arc extinguishing cover, and appearance are burned. If so, clear the stains, remove the arc extinguishing cover to check, fix or replace the matching defective components.

6. Check and replace rubber accessories:

Rubber accessories should be often checked and replaced since they are prone to aging in high temperature surroundings. Rubber accessories have a complicated construction, and stringent sealing performance standards call for. The main factor guaranteeing the circuit breaker’s functioning is timely replacement of rubber components.

7. Check the electrical connection:

Check often whether the circuit breaker’s terminal connection is strong to guarantee no looseness. Tightening the connection of the terminal in line with the prescribed torque will help to prevent failures resulting from inadequate contact.

8. Avoid frequent starting:

– Molded case circuit breakers are not suitable for special occasions such as motors, electric heating equipment, capacitor cabinets, high inductive or high capacitive loads and high temperature environments that are frequently started. Regular starting will instantly raise the current, which could trip the circuit breaker.

9. Check and adjust the protection settings:

In high temperature environments, the overload protection thermal bimetallic elements of the circuit breaker may be affected. To satisfy the needs of the on-site equipment operation, the instantaneous protection setting multiple of the circuit breaker must be somewhat adjusted.

10. Regular inspection and testing:

Measure the terminal’s and the wire connection part’s temperatures often with a thermometer. Normal conditions should see it not more than 50 degrees above room temperature. Should it be more than, see whether the connection is loose.

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In extremely high temperature environments, the maintenance of molded case circuit breakers is crucial. By implementing effective maintenance measures, not only can the stable operation of the circuit breaker be ensured, but also the safety and reliability of the entire power system can be improved. Regular inspection, cleaning, adjustment and testing are the key to ensuring long-term and stable operation of the equipment.