What precautions should be taken when operating a handcart circuit breaker?

Handcart circuit breakers (also known as withdrawable or drawer-type circuit breakers) are critical equipment in high-voltage switchgear. Their operation involves high-voltage power and mechanical interlocking, and safety regulations must be strictly followed. The following are the main precautions to take when operating handcart circuit breakers:

I. Pre-operation Preparation

 

Qualifications and Supervision

Operators must hold a high-voltage electrician's certificate and have undergone specialized training.

At least two people must operate the equipment: one to supervise and one to operate. Single-person operation is strictly prohibited.

Safety Protection

Wear insulated gloves, insulated boots, safety glasses, and other safety equipment.

Check that the operating area is free of debris and ensure that emergency exits are unobstructed.

Status Confirmation

Verify the switchgear number and equipment name to prevent misoperation.

Confirm that the circuit breaker is in the open position using mechanical/electrical indicators (the trolley can only be moved when the circuit breaker is not energized).

 

II. Operating Procedures and Precautions

 

1. Handcart Insertion/Exit (Move to Working/Test Position)

Power Deactivation Confirmation: Before operation, the circuit breaker control power supply must be disconnected to ensure the circuit breaker is in the open position.

Position Alignment: Align with the guide rail and smoothly push in or out, avoiding jamming. If the resistance is too high, stop operation and check.

Position Locking:

Working Position: The handcart should be fully inserted, the secondary plug should automatically connect, and the mechanical interlock should lock.

Test Position: The main circuit is disconnected, the secondary circuit is connected, and remote/local opening and closing tests can be performed.

Maintenance Position: The handcart is completely removed from the cabinet, and both the main and secondary circuits are disconnected.

2. Circuit Breaker Opening and Closing Operation

Remote Operation: When operating from the control room or through the automation system, it is necessary to confirm that no one is on site for maintenance.

Local Operation:

Before closing, check whether the grounding switch is disconnected (if so).

Immediately after operation, check the indicator lights and mechanical indicators to confirm the opening and closing status.

3. Grounding Switch Operation

Strict Sequence:

During power outage: First open the circuit breaker → move the trolley to the test/maintenance position → then close the grounding switch.

During power restoration: First open the grounding switch → move the trolley to the working position → then close the circuit breaker.

Interlock Protection: Forced unlocking is strictly prohibited; ensure the mechanical/electrical interlocks are effective.

 

III. Safety Precautions

 

Live Operation Prohibited:Do not crank the trolley while the circuit breaker is not tripped.

Forced Operation Prohibited:If obstruction occurs, stop immediately and investigate the cause (e.g., guide rail deformation, interlock not disengaged, etc.).

Unauthorized Unlocking Prohibited:The emergency unlocking key must be kept by a designated person and should not be used except in emergencies.

Skipping Steps Prohibited:Strictly follow the operating procedure; do not skip steps or combine operations.

 

IV. Special Operating Condition Handling

Abnormal Sounds/Odors:If you hear abnormal noises or smell a burning odor during operation, stop immediately and report it.

Insulation Check:Before the first operation after maintenance, confirm that the insulation resistance is within acceptable limits (especially in humid environments).

Anti-misoperation Interlocking System:If the microcomputer anti-misoperation system malfunctions, manual operation is only permitted after approval from the technical supervisor.

 

Key Points Summary

 

Power off and test for voltage before operation; crank the handcart after tripping the switch; do not forcibly break interlocks; ensure correct positioning; grounding sequence must not be reversed; ensure thorough monitoring for safety.

The core of operating a handcart circuit breaker lies in strictly adhering to the operating ticket system, respecting the interlock design, and maintaining rigorous status verification. Any negligence may lead to arcing short circuits, equipment damage, or personal injury; exercise extreme caution!

 

Shaanxi Huadian's handcart circuit breakers feature a self-developed permanent magnet mechanism/spring mechanism (optional), dual mechanical and electrical interlocking, and have passed national authoritative testing with a zero error rate. For inquiries, please contact us:pannie@hdswitchgear.com.