Information
If digital inputs or outputs of standard actuator controls are connected to the safety
PLC, imperatively ensure sufficient absence of interference of all non-safety-related
system components with regard to the safety function. The absence of interference
must be guaranteed even in case of standard component faults. For this, galvanic
isolation between safety-related and non safety-related system components is im-
portant (but not necessarily sufficient).
Performing a PVST includes diagnostics of the safety-related components. This
ensures improved safety figures compared to applications without or with minor
diagnostics.
8.4.
Proof test (verification of safe actuator function)
The proof test serves the purpose to verify the safety-related functions of the actuator
and actuator controls.
Proof tests shall reveal dangerous faults which might be undetected until a safety
function is started and consequently result in a potential danger.
Information
During execution of the proof test, the safety function is unavailable for a short time.
Depending on both version and configuration, the proof test includes the
following tests:
1.
Check Safe ESD safety operation (Safe OPENING/CLOSING).
2.
Check SIL fault signal “Actuator monitoring”.
3.
Check Safe ESD reaction for “Motor protection (thermal fault)” signals.
4.
Check Safe ESD reaction to “Limit seating with overload protection” (limit and/or
torque evaluation).
5.
Check Safe ESD reaction to “Forced limit seating in end position” (limit evalu-
ation) – for actuators with electromechanical control unit.
6.
Check Safe ESD reaction to “Forced limit seating in end position” (limit evalu-
ation) – for actuators with electronic control unit and limit switches.
7.
Check Safe ESD reaction to “Forced torque seating in end position” (torque
after limit evaluation).
8.
Check Safe ESD reaction for “no seating” (no evaluation of limit and torque).
9.
Check Safe STOP function.
10. Check combination of Safe ESD and Safe STOP function.
The safety-related signal input is appropriately assigned to check the safety-related
function. As a consequence, the actuator has to perform the safety function. For a
detailed description of the proof test steps refer to the following sections.
Intervals:
A proof test interval describes the time between two proof tests. Functionality must
be checked at appropriate intervals. The intervals are to be defined by the plant
operator. The probability of failure on demand (PFD) depends on the selected proof
test interval; in our example, it is valid for T
proof
= 1 year (refer to <Safety-related
figures> chapter).
In any case, the safety-related functions must be checked after commissioning and
following any maintenance work or repair as well as during the T
proof
intervals defined
in safety assessment.
If a fault occurs during proof test, safe function has to be ensured introducing
alternative actions. Please contact AUMA Riester GmbH & Co. KG.
The type of proof test to be performed depends on version and configuration of the
product. Only the tests applicable have to be performed.
Information
If the safety function has been configured as ESD CLOSE/CLOSE + Safe STOP
OPEN/CLOSE or as ESD OPEN/OPEN + Safe STOP OPEN/CLOSE, all relevant
tests for Safe ESD and for Safe STOP (as well as for the combination of Safe ESD
and Safe STOP) must be executed.
Information
Before starting the test we recommend reading the respective test procedure at least
once.
29
Part-turn actuators
with AC 01.2-SIL/ACExC 01.2-SIL
Tests and maintenance
