Delayed Outputs
By connecting the JSR3T expansion relay to a compatible safety relay it is easy to obtain safe "delayed" outputs.
The JSR3T provides the system designer with the facility to hardwire selected time delays in steps between 0.5 and 10 seconds.
Use of Delayed Outputs
There are many applications where delayed outputs are necessary and permissible. For example delayed stop signals can be used for emergency stops according to EN418 § 4.1.5 Stop Category 1 (a controlled stop with power to the machine actuators) available to achieve the stop and then removal of power when stop is achieved). Stop Category 1 may also be permitted when it is not possible to gain physical access to the machine before the safe stop is effected, e.g. by:
- Covers and Gates which are locked until dangerous operations and functions have been stopped.
- Long distances between a safety device and dangerous machine functions.
Using this technique of stopping a machine provides many advantages i.e.:
- Machines last longer as they are not subjected to excessive loading, etc. when requested to stop.
- Parts being processed are not damaged.
- Restarting machines from stopped position is simplified.
A safe 'soft' stop is achieved by means of a safety relay giving a programmed stop to the machine control system, e.g. when a gate is opened or emergency stop is activated. The output of the safety relay is used to provide both a stop signal to the machine control system, i.e. via a PLC which applies the necessary braking/stopping of the machine in a controlled way, and to switch a delayed expansion relay, e.g. JSR3T. The delayed safety outputs of the JSR3T expansion relay are then used to control the safe disconnection of the power to the actuators/motors, etc. of the machine.
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Expansion Relay with Delay for:
- Hardwire Selection of Delay Time
- Delayed Safety Outputs
Features:
- Hardwire selectable delay 0.5 - 10.0 seconds by hardwire links and time trim potentiometer
- Width 22.5 mm
- Output indication
- 2 x 1 NO relay outputs
- 24 VDC/VAC
Safety Level
The JSR3T has twin stop functions, using two positively guided contact relays.
In order to achieve the level of monitoring required the JSR3T must be used with a suitable safety relay, e.g. JSBR4, JSBT5, etc. The JSR3T test output (terminals X1 and X2) must be connected to the test input of the safety relay being expanded. (See connection examples.)
The JSR3T provides delay times that even in the event of an internal fault condition complies with the requirement that the set delay cannot increase in time.
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