International standard EN / IEC 61800-5-2

The standard IEC 61800-5-2 (in Europe EN 61800-5-2) deals with the functional safety requirements of “adjustable speed electrical power drive systems”. Part 5-2 of the international standard series IEC / EN 61800 is a product standard for electrical drive systems with integrated safety functions. Part 5-2 specifies the requirements for the development of safe drives in terms of their functional safety considerations.

Manufacturers can install safe drives in plant and machinery in accordance with the specifications of the overarching standards EN / IEC 61508 (generic standard for functional safety of electrical and electronic systems), EN / IEC 62061 (functional safety of machine control systems) and EN ISO 13849 (machinery safety) by implementing and complying with the normative regulation.

The standard EN 61800-5-2 divides safety functions into stop functions and miscellaneous safety functions such as safe motion functions or safe brake functions.

Safe stop functions in accordance with EN 61800-5-2

When considering safety on axes, the main factors are to prevent the axes from starting up unexpectedly and to shut down moving axes safely in the case of danger. IEC / EN 61800-5-2 defines three stop functions, which correspond to the three stop categories 0, 1 and 2 from EN / IEC 60204-1:


EN / IEC 60204-1 EN / IEC 61800-5-2
Stop category 0

Safe torque off STO

Stop category 1 Safe stop 1 SS1
Stop category 2 Safe stop 2 SS2

If the safety functions detect errors or limit value violations, defined reaction functions must be initiated. EN / IEC 61800-5-2 frequently talks of the limiting of speeds or positions. This is achieved by initiating a motor stop as a reaction function if a limit value is violated. There are also applications in which a direct shutdown in the case of a limit value violation is merely reported by the individual axis and a higher-level safety controller takes care of coordinated braking of the entire system of axes. External monitoring relays can equally merely report limit value violations. In combination with a safe shutdown path, the requirements of the normative safety functions can then be satisfied. A drive-integrated motion monitoring solution can be implemented with our PMCprotego DS.

Safe motion functions in accordance with EN / IEC 61800-5-2 and safe monitoring functions

In addition to the stop functions, IEC 61800-5-2 also describes the “safe motion functions”, which are intended to reduce risks during operation. A safe monitoring function can be considered as an additional safety function: The monitoring function is based on the normative motion function. Exceeding the parameters set for limit values is reported, but does not trigger an error reaction function.

Safe motion functions Safe monitoring functions
Safe direction (SDI) Safely monitored direction (SDI-M)
Safely limited increment (SLI) Safely monitored increment (SLI-M)
Safely limited speed (SLS) Safely monitored speed (SLS-M)
Safe operating stop (SOS) Safely monitored operating stop (SOS-M)
Safe speed range (SSR) Safely monitored speed range (SSR-M)
Safely limited position (SLP) Safely monitored position (SLP-M)
Safely limited acceleration (SLA) Safely monitored limited acceleration (SLA-M)
Safe acceleration range (SAR) Safely monitored acceleration range (SAR-M)

You can rely on Pilz products for safe motion monitoring!


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