Maximum operating current of control elements: understanding the characteristics and avoiding mistakes when choosing equipment

Many specialists encounter the fact that the maximum operating current of a switching device can be specified differently, but it is this parameter that directly impacts the safety and reliability of the equipment. In our article, we presented a comparison of control elements depending on their application category and shared examples of the consequences that can arise from an incompetent approach to selecting the application category in electrical circuits.

It's important to remember that each switching device operates in specific electrical circuits—either control or power circuits. Furthermore, each device has its own application category. This category specifies the parameters and characteristics required for the equipment during standard operation.

The following are intended for switching control circuits:

• Return buttons
• Snap-on buttons
• Backlit buttons

Current up to 10 A!
GOST IEC 60947-5-1

Main application categories:
AC-15, DC-13
Switching circuits with electromagnets: relay coils and contactors.

The following are intended for switching power circuits:

• Cam switches
• Load switches
• Switches

Current up to 85 A!
GOST IEC 60947-3

Main application categories:
AC-3, AC-23

Switching circuits with electric motors or other highly inductive loads.

In the technical documentation of some manufacturers, two common methods of artificially increasing the maximum operating current are sometimes encountered:

• Current without a usage category. Documentation may indicate a high current (e.g., 16 A), but the usage category is not specified. At first glance, this figure appears impressive and creates a sense of reliability. However, it's important to remember that such a figure is only achievable under certain conditions.
• Category substitution. The manufacturer accurately states the current, but selects a "lighter" application category, which inflates the ratings. A classic example: instead of category AC-15, intended for heavy loads (e.g., controlling powerful electromagnets), they specify category AC-12, which is used for light loads where the contacts are subject to minimal stress (e.g., controlling photocells).

Consequences of using controls with the wrong category selected in electrical circuits:

• Burning (welding) of silver-plated contacts.
• Thermal destruction.
• Failure of security functions.

Our company is committed to integrity and complete transparency in explosion safety matters. We offer Ex e-rated control elements in the KG and PG series with the following technical specifications:

This approach ensures that customers receive reliable data and can confidently use equipment in environments where reliability and safety are particularly important.