[admin]

In the field of industrial safety, Trapped key interlocking is an effective safety control solution, which is widely used in high-risk industries such as manufacturing, electric power, chemical industry, transportation, etc. Its core advantage lies in the use of the "key transfer" mechanism to achieve physical interlocking, effectively preventing safety accidents caused by misoperation or wrong operation sequence. This article will focus on the core principles of trapped key interlocking, combined with typical application cases in multiple industries, from manufacturing to energy, to explore in depth how it can build a solid security line for enterprises.

1. Basic principles of Trapped key interlocking

Trapped key interlocking is a safety interlocking system based on mechanical key transfer. Its core concept is "key is authority", that is, the opening of a certain operation or equipment must be based on the safe completion of the previous operation, and the sequence control is achieved through the physical transfer of the key.

The system usually consists of the following components:

Key exchange device: used to assign or recover operation permissions;

Door lock or panel lock: control the physical access of mechanical or electrical devices;

Valve lock: used to control gas, liquid or steam valves;

Power isolation lock: ensure that the equipment is powered off before entering the maintenance area;

Logic interlock module: realize complex process control.

This system does not rely on electronic control logic, so it is particularly suitable for harsh environments such as high temperature, high humidity, and severe electromagnetic interference. It is a safe and reliable "hard interlock" solution.

2. Manufacturing industry application case: assembly line equipment maintenance safety

Background:

A certain automotive parts manufacturing plant has multiple automated assembly lines, the assembly line equipment runs fast, and daily maintenance is frequent. In order to prevent personnel from entering or accidentally contacting high-voltage components during equipment operation, the factory introduced a trapped key interlock system.

Application method:

The power-off key switch is installed in the main control cabinet, and the key can only be pulled out after the power is completely off;

The worker uses the key to unlock the door lock of the equipment guardrail and enter the maintenance area;

Before the door is closed and relocked, the key cannot be returned to its position and the system cannot be powered on again.

Effect:

The accident of "accidentally entering the operation area" is eliminated;

The sense of security and operational standardization of maintenance workers are improved;

The whole system does not need to rely on PLC control or sensor linkage, and the maintenance cost is low.

3. Application Case in Chemical Industry: Reactor Maintenance Protection

Background:

The production process of a fine chemical enterprise involves high-pressure and high-temperature chemical reactors, and daily maintenance is a high-risk operation. Traditional handwritten maintenance applications or paper records of operation procedures have problems of inadequate implementation.

Application method:

The steam valve of the reactor is equipped with a trapped key interlock valve lock, and the key can only be released when it is closed;

The pulled out key is used to unlock the door lock;

Before the maintenance door is closed and locked again, the steam valve key cannot be recovered to ensure that it cannot be operated under pressure.

Effect:

Established a forced sequential logic: only by closing the valve → maintenance → closing the door → can the equipment be reactivated;

Effectively prevented accidents caused by "opening under pressure" that caused burns to personnel;

Rated as a "low-cost and high-efficiency" safety upgrade model by the safety supervision agency.

4. Data Center Application Case: Access Control for Restricted Areas

Background:

The data center of a large cloud service provider involves multiple levels of permission isolation spaces (such as server host rooms, power management areas, etc.). For compliance and data security needs, the access path is controlled.

Application method:

Each access restricted area is equipped with a mechanical interlocking system;

High-authority operators control the door locks to the next area by releasing the key;

Some areas are equipped with cross-key interlocking to prevent multiple people from operating at the same time and enhance audit traceability.

Effect:

Improved the physical security level;

Combined with the electronic recording system, physical + electronic dual certification is achieved;

Successfully passed ISO 27001 and T3+ security level certification.

5. Power and Energy Industry Application Case: Substation Isolation Operation

Background:

Substations involve multiple sets of high-voltage disconnectors and grounding switches. Manual misoperation may cause serious arc accidents or personal injury. A State Grid partner introduced a trapped key interlocking solution for the isolation operation of 110KV substations.

Application method:

First, operate the circuit breaker to control the key switch to cut off the power;

Then use the key to open the grounding knife switch operation lock;

The key is transmitted in series during the whole process, and the process is forced to be unique;

Only when all steps are executed in sequence can the system be reset.

Effect:

It realizes the mandatory logical interlocking without electronic control;

All isolation operations are transferred through keys and have complete records;

It complies with the safety standard of "operation cannot be parallel" in the "Electric Power Safety Regulations".

6. Mining industry application case: Underground underground operation area authority management

Background:

In mine operations, ventilation, conveying systems, power supply isolation and other links are complex, underground signals are unstable, and traditional electronic interlocking systems are difficult to operate stably.

Application method:

A key distribution control station is set up at the entrance of the mine;

Workers obtain designated keys according to the work tasks and open the work area;

If the key is not returned, the exhaust and power supply cannot be enabled to ensure the safety of subsequent personnel.

Effect:

Effectively improve the "controllability" and "visibility" of underground operations;

Each operation leaves a physical trace, which is conducive to accident tracing;

Compensates for the blind spots of electronic monitoring and enhances system stability.

Through the application cases of the above-mentioned multiple industries, it can be seen that the Trapped key interlocking system not only has a high degree of security protection capabilities, but also becomes the preferred security protection solution for many key industries because it does not rely on complex electronic control systems, has strong stability and simple maintenance.

Its main advantages are:

High reliability: all-mechanical structure, strong anti-interference ability;

Anti-misoperation: strict logic, must be executed in sequence;

Wide adaptability: suitable for various harsh environments, including high temperature, high humidity, and strong electromagnetic interference areas;

Strong scalability: can be used in combination with electronic access control systems and data recording systems.

From the assembly line of the manufacturing industry to the high-voltage isolation of the energy system, from the high-temperature equipment maintenance of the chemical plant to the physical authority control of the data center, the Trapped key interlock system has demonstrated its irreplaceable security value. If you need to know more about trapped key interlock system solutions or customized lock configurations in different application scenarios, please contact us. We will provide you with professional interlock system products and consulting support.

http://www.nudango.com
Shanghai Nudango Safety Equipment Co., Ltd.

[Author]

Posts