User Manual

SAFETY
Safety handbook page - 19 -
PNSPO
5.2 Requirements for Door monitoring
Door monitoring must ensure that the safety door is protecting the hazardous area as
defined in the risk assessment ( EN1050).
The sensors and the signal processing must comply with
all required norms and directives.
- Switches must be designed to withstand all expected and foreseeable stresses
- Switches must comply with safety standards especially direct opening contacts and
safety door switches must be used.
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The principles of redundancy and diversity must be considered in the mechanical
design of switches and signal processing.
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The signal processing must be designed to be in accordance to the categories of
EN954-1 defined in the risk assessment.
5.3 Requirements for Door interlocking
An interlocking device with guard locking shall be used when the stopping time is
greater than the access time taken by a person to reach the danger zone.
Device intended to lock a guard in the closed position and linked to a control system so
that:
• the machine cannot operate until the guard is closed and locked;
• the guard remains locked until the risk has passed.
For applications requiring frequent access, the interlocking device shall be chosen to
provide the least possible hindrance to the operation of the guard. In that case also
requirements of intended use, conditions of use, risk assessment and stopping time
and access time must be taken in to account.
Mechanically actuated devices:
There are three types of mechanical actuation. These are:
Cam operated actuation
When one single detector is used it shall be actuated in the
positive mode since, among other characteristics, this mode of
actuation prevents the detector from being defeated in a simple
manner.
A higher level of protection against defeat can be achieved,
e.g., by enclosing the cam and detector in the same housing.