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line monitoring for ‘nc’ emergency push buttons

line monitoring for ‘nc’ emergency push buttons

line monitoring for ‘nc’ emergency push buttons

(OP)

We have requirement of line monitoring of Emergency pushbuttons connected to UCP. Please explan how the wirirng configuration will be

What toy of E pushbutton ( no of contacts 2NO +2NC) I need o buy ?

Regards

Ayyappan

RE: line monitoring for ‘nc’ emergency push buttons

You need to buy the type specified by the qualified engineer who designed the emergency stop system. I wouldn't like to think my life depended on a safety system designed by someone who didn't know how to specify the correct switch for the purpose.

RE: line monitoring for ‘nc’ emergency push buttons

(OP)

My query is E -stop is connected in NC contact meaning it is fail safe. what is the other advantage of adding a line monitoring to a fail safe wiring ?
when there cable breakage the system will trip
Please see the attachment, one vendor suggested to use EOL and In line resistor to monitor, expert comments please

RE: line monitoring for ‘nc’ emergency push buttons

There is no attachment to your post...

If there are multiple causes that affect the system trip, a line monitor will help you or operations identify exactly what shut the system down.

So, if there are 68 items that can cause a system shutdown, you will know that it was the E-Stop that shut down the unit if it was pushed (or line break).

Assuming the line monitoring goes to a PLC/DCS that records history or a Sequence of Events recorder.....

______________________________________________________________________________
This is normally the space where people post something insightful.

RE: line monitoring for ‘nc’ emergency push buttons

Have a look at the safety relays made by Pilz and others. These relays actively monitor the stop circuit to reduce the probability of a fail-to-danger situation. More sophisticated than an EoL resistor.

RE: line monitoring for ‘nc’ emergency push buttons

You have several pushbuttons. If the system shuts down how do you know which button it was?

If you use a button with 1 NC and 1 NO you can wire the NO contact back to the control panel and read it with an analog input or simple Voltmeter
One way I have seen on a 2 kilometer conveyor was to have a series resistor at each switch feeding one side of the NO switch with 1V, 2V, 3V, 4V etc when a switch was pulled by the Voltage feeding back the operator knew which switch was pulled, if 2 switches were pulled it would display the closest one first. A 4 core cable was used daisy chaining from switch to switch.

Of course if all your switches are close you can wire them all back to a common location and monitor them with a PLC inputs, whatever you do don't compromise the ability of the switches to interrupt the power to the safety shutoff device.

RE: line monitoring for ‘nc’ emergency push buttons

(OP)
Thanks all for sharing your ideas and views

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