R
13 Posts in this encyclopedia categoryRated voltage
The rated voltage of a relay is the voltage for which the winding,
including additional built-in components, is rated and designated and to
which the other characteristics refer.
Recirculation loop
Monitors controlled actuatorsThe SAG can only be activated
when the feedback loop is closed. Safe feedback is provided, e.g. for
relays or contactors, with positively driven contacts. Series-connected
NC contacts of the monitored relays are integrated into the feedback
loop of the SAG. If a contact in the enabling current path welds,
reactivation of the SAG is no longer possible because the feedback
circuit remains open.
Redundancy
Presence of more than necessary for the function. Several functional
groups are used for the same function (e.g. more channel structure). In
safety engineering, especially the "duplication of critical components"
[EN ISO 12100-2].
Relapse delay
When the operating voltage is applied, the timing relay immediately
switches to the operating position. If the operating voltage is
interrupted, the off-delay time begins. After the delay time has
elapsed, the timing relay switches to the off-position. A distinction is
made between the variants with or without control signal.
Requirement class (AK)
According to DIN 19250, assignment of requirements for the realisation
of the protective device, which should lead to a safety-related
performance of the device appropriate to the risk. It essentially
results from the product of the extent of damage and the probability of
occurrence.
Reset button
Reset button in a SAG represents a restart interlock, which is only cancelled by actuation.
Response delay
The unit is started by applying the operating voltage. After the set
delay time has elapsed, the time relay switches to the operating
position.
Restart interlock
Preventing the release of a SAG after a shutdown, after a change in the
operating mode of the machine or after a change in the actuation mode.
The restart interlock is only released by an external command (e.g.
reset button).
Reversing contactor
Reversing contactors are used to change the direction of rotation of
rotary motors, to start them smoothly and/or to monitor their load.
Furthermore, the reversing contactor can inform you about the operating
status of the motor via a diagnostic function.
Risk assessment
Assessment of safety-related requirements, taking into account extent of damage, probability of occurrence, risk classification.