Understanding Intrinsic & Extrinsic Protection Principles

Intrinsic Protection

Intrinsic protection refers to the built-in safety features or mechanisms that are inherent to a components design. These features are designed to protect the equipment itself and ensure its proper operation. Intrinsic protection can include various elements such as thermal protection, overload protection, short-circuit protection, and voltage surge protection. These features are integrated within the motor to automatically detect and respond to abnormal conditions or potential hazards, safeguarding the equipment from damage and preventing unsafe operation. For example, thermal protection is a common intrinsic protection feature in motors that monitors the motor's temperature and automatically shuts it down if it exceeds safe limits. Similarly, overload protection mechanisms can detect excessive current draw and prevent the motor from overheating. These intrinsic protection measures are typically incorporated into the motor's design to ensure reliable and safe operation under normal and abnormal conditions.

Extrinsic Protection

Extrinsic protection refers to external devices or systems that are added to a system or operating environment to provide an additional layer of protection. These external protection measures are implemented to safeguard the component and the surrounding equipment or personnel from potential hazards or faults. Extrinsic protection can include components like fuses, circuit breakers, protective relays, and insulation systems. For instance, fuses and circuit breakers are commonly used as extrinsic protection devices to interrupt the electrical current in case of a short circuit or excessive current flow. Protective relays are another example of extrinsic protection used to monitor various parameters such as voltage, current, and temperature and initiate protective actions if predefined thresholds are exceeded. Insulation systems, such as motor enclosures and protective covers, can also be considered as extrinsic protection measures as they provide a physical barrier to protect the motor from external environmental factors. Both intrinsic and extrinsic protection measures are important to ensure the safe and reliable operation in various applications.

ATEX (Atmosphères Explosibles) protection in motors refers to the specific safety measures implemented in motors to ensure their safe operation in potentially explosive atmospheres. ATEX is a European Directive that sets out the requirements for equipment used in environments where there is a risk of explosion due to the presence of flammable gases, vapors, mists, or combustible dust. Equipment that is to be used in a potentially hazardous area should be inherently safe, therefore intrinsic safety measures should form part of their make up to ensure that each component cannot itself, be a source of ignition. Typical ATEX Marking  Intrinsic protection principles in ATEX motors for example involve incorporating design features and components that prevent the motor from becoming an ignition source in explosive atmospheres. Intrinsic safety EX I is a different level of protection and should be researched accordingly. Ex I intrinsic safety I an explosion protection concept in which the electrical energy within the equipment is restricted to a level below the ignition point of the equipment.


Some common intrinsic protection principles, not Ex I, employed in ATEX motors include:  

Increased Safety (Ex e): ATEX motors designed with increased safety protection have specific measures in place to prevent the generation of sparks or excessive temperatures. This can include enhanced insulation, restricted clearances, and specially designed terminals to minimise the risk of sparking. Learn more about motor protection characteristics of Ex ec and Ex eb.

Flameproof (Ex d): Flameproof motors are designed to withstand an internal explosion and contain it within their enclosure. The motor enclosure is constructed to withstand the pressure generated by an explosion and prevent it from propagating into the surrounding atmosphere. Non-Sparking Construction: ATEX motors often employ non-sparking materials, such as copper-free aluminum, to minimise the risk of generating sparks during operation.

Temperature Limitations: ATEX motors have surface temperature limitations that ensure that the motor does not exceed safe temperature limits that could lead to ignition either through overheating, or by contributing to a gas spontaneously igniting on contact with hot surfaces, known as hot surface ignition. Learn more about auto ignition and hot surface ignition.

It is important to note that ATEX intrinsic protection measures vary depending on the specific ATEX classification and zone requirements for the given hazardous environment. The purpose of these intrinsic protection principles is to minimise the risk of ignition and explosion in potentially explosive atmospheres, ensuring the safe operation of motors in such hazardous locations. To accurately determine the level of protection required in a hazardous area, the hazardous area classification will give clarity by clearly stating the gas or dust zone in which the equipment will be placed. From here, equipment suppliers will match components against this specification to ensure that the correct level of protection is offered by the equipment.  

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