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Safety FAQ - 17750 | Universal Robots

This section contains questions and answers on different

safety topic s related to the installation and use of UR robots.

Topic: Definit ions

Question Answer

What is a

“Stop

Category”?

“Stop Category” is a classification of how robot

motion is stopped in a safe way. There are three

different types.

See the topic "UR Robots Safety" below.(See IEC 60204-1 or EN 60204-1 for more details)

What is ”Cat 3”

or

”Category 3”?

The term “Category” should not be confused with

the term “Stop Category”.

“Category” refers to the type of architecture used as

basis for a certain “Performance Level”. A

significant property of a “Category 3” architecture is

that a single fault cannot lead to loss of the safety

function.

(See ISO 13849-1 for more details)

What is ”PLd” A Performance Level (PL) is a discrete level used

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or

”Performance

level d”?

to specify the ability of safety-related parts of

control systems to perform a safety functions under

foreseeable conditions. PL=d is the second highest

reliability classification, meaning that the safety

function is extremely reliable. (See ISO 13849-1 for more details)

What is SIL 2? SIL (Security Integrity Level), like Performance

level, is a measure of how likely it is that a

dangerous failure will occur in a system. SIL 2

roughly equivalent to PL d (performance level d).(See IEC 62061 or EN 62061 for more details)

Topic: Risk Assessment

Question Answer

What is a risk

assessment?

A risk assessment is the overall process of

identifying all risks and judging if they are reduced

to an appropriate level. It includes both risk analysis

and risk evaluation.

A risk assessment must be documented. See UR

user manual.(See ISO 12100 or EN ISO 12100 for more details)

What is a risk

analysis?

A risk analysis is a combination of the specification

of the limits of the robot installation, hazard

identification and risk estimation.

(See ISO 12100 or EN ISO 12100 for more details)


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What is a risk

estimation?

Risk estimation is defining likely severity of harm

and probability of its occurrence.


What is a riskevaluation?

A risk evaluation is the judgment, on the basis of risk analysis, of whether the risk reduction

objectives have been achieved.

What is a

residual risk?

A residual risk is the risk remaining after protective

measures have been implemented.


Topic: Standards

Question Answer

Is it requiredfor robots to

comply with

ISO 10218-1?

No, it is required to comply with the laws andregulations in the country and/or the state that the

robot is installed in.

See UR user manual.

Do UR robots

comply withISO 10218-1?

Not all guidance in ISO 10218-1 is clear and/or

applicable for collaborative robots. At the time whenISO 10218-1 was written, collaborative robots was

a new and developing field. Some features

described in ISO 10218-1 assumes

non-collaborative, big, heavy, dangerous and

fenced robots. A Technical Specification with

clarifications on the features described in ISO

10218-1 is published in February 15th 2016 under

the name ISO/TS 15066.


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Question Answer

What is a Stop

Category?

“Stop Category” is a classification of how robot

motion is stopped in a safe way. There are three

different types:

- Stop Category 0 : Robot motion is stopped by

immediate removal of power to the robot. It is an

uncontrolled stop, where the robot can deviate from

the programmed path as each joint brake as fast as

possible. This protective stop is used if a safety-

related limit is exceeded or in case of a fault in the

safety-related parts of the control system.

- Stop Category 1 : Robot motion is stopped with

power available to the robot to achieve the stop

and then removal of power when the stop is

achieved. It is a controlled stop, where the robot

will continue along the programmed path. Power is

removed as soon as the robot stands still.

- Stop Category 2 : A controlled stop with power

left available to the robot. The safety-related control

system monitors that the robot stays at the stop

position.(see IEC 60204-1 and ISO 13850 for more details)

Which Stop

Category is

used for

emergencystop in UR

robots?

The UR robots emergency stop is designed as a

Stop Category 1 stop.

See above.

Topic: UR Robots Safety


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