Machines makes the work simple, fast & efficient if used in a safe useful manner. But that same machine can be a reason of disaster if a single wrong step been taken.
That’s why for the safety; Safety of humans & machines; safety measures are being applied on the machine like Emergency push button !.
The function of reset is possible with the help safety relays. In this post, We will talk about the Safety Relays. For better understanding we are explaining the safety relay UE43-3AR BY SICK.
SAFETY RELAY UE43-3AR BY SICK
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- Input channels These are the inputs from the system whose presence across the relay defines that system is healthy.
- Reset terminal Reset terminal is a type of indication input to relay which says that operator knows about the current condition & further operator is giving command to system to get run.
- Output Relays These relays works at last when both conditions get fulfilled- All the inputs across input channels & control supply at reset terminal. On getting both the conditions fulfilled relay output get produced.
CIRCUIT OF SAFETY UE43-3AR by SICK
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- A1 & A2 are the power supply of the electronic module.
- S11 & S21 are the control supply positive & negative respectively.
- +S12 input channel 1.
- +S52 & -S22 are input channel 2.
- S34 is the reset terminal.
- 13 & 14, 23 & 24, 33 & 34 are the NO contacts of output relay.
- 41 & 42 are the NC contact of output relay.
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TIMING DIAGRAM OF SAFETY RELAY UE43-3AR BY SICK
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Reset terminal is permanently connected with positive supply. Whenever input get available on both the input channels, output get active after fixed time interval.
Further when input supply to any of the channel goes off, Output get inactive after fixed time interval. (Clearly seen in a timing diagram above)
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Reset command to reset terminal is being given manually. After fixed interval of reset command In the presence of input, Output get active. Whenever input disappear, relay demands for reset signal even in the presence of input channel.
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SAFETY RELAY EXPLANATION WITH APPLICATIONS
For better understanding, Next we are discussing the safety relay use with Air compressor unit.
Safety relay installation on air compressor unit
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- Air compressor unit consists of electric motor connected with the mechanical mechanism.
- Mechanical mechanism with the help of Electrical motor compresses the air inside the air storage tank.
- Air compressor operates under the desired permissible pressure limit.
- In auto mode it works continuously in a cycle, Whenever pressure reaches the upper limit power to motor goes off, On reaching the particular lower limit of pressure; It get back ON again.
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- Reset terminal is connected with +supply through NO push button.
- Channel 1 is connected with +supply through emergency NC contact.
- Channel 2 (S52) is connected with +supply through pressure & temperature switch. Both the switches are NC contacts are connected in series.
- Channel 2 (S22) is connected with -supply directly.
- Control supply to motor’s contactor is given through the relay NO contact 13-14. Contact connects only when system is healthy.
- An Alarm is connected at 41-42 NC terminal of safety relay so that alarm get produced when relay get unhealthy.
SUM UP
- The post discusses the importance of safety measures in modern machines, particularly through the use of safety relays like the UE43-3AR by SICK.
- It emphasizes that while machines can enhance efficiency, improper use can lead to disasters.
- Safety relays include input channels, a reset terminal, and output contacts, ensuring a machine operates only when conditions are safe.
- The post explains the wiring circuit for the safety relay, including automatic and monitored reset functionalities.
- It provides an example of installing safety relays in an air compressor system, highlighting their role in enhancing safety and preventing malfunction through alarms and emergency switches.