Timed delay relay on start up of machine.

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  #1  
Old 11-17-14, 01:51 PM
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Timed delay relay on start up of machine.

I want a sounder to go off when the start button is pressed on the equipment, sounder to run for a couple seconds, sounder stops and machine starts.
I've done little research so far but wanted to post here first.
Suggestions on how to do this? 24VDC can be made available.

So at guess what happens, voltage will go to the time relay and run voltage to the sounder through a NC contact, timer will then engage and latch on NO for the start signal & stopping the sounder.
Because the relay would already be latched I'm guessing it then won't be possible to sound the alarm every time the button is pressed while running, which is obviously what i want. Hope that makes some sort of sense.

There is also a mitsibushi PLC but I can't see any spare outputs, if this was an option I'm guessing the program could be modified and a timer added that way with an output to the sounder.

Thanks in advance
 
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Old 11-17-14, 02:12 PM
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Old 11-17-14, 06:19 PM
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Okay further investigating. Start signal from button goes straight to PLC. So i'll need something that will recognize a pulse of 24vdc, sound the alarm and then send a pulse signal to the plc. This would be far easier if the sounder went off as the machine starts but needs to be before
 
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Old 11-17-14, 06:35 PM
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So you will need a circuit that will interrupt the 24vdc from the start button.

I'm guessing it then won't be possible to sound the alarm every time the button is pressed while running
I don't understand why if the machine was started that you would need to push the start button again for the sounder to sound again.
 
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Old 11-17-14, 07:04 PM
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Sorry what I've said is probaly a little confusing. What I ment was if someone was to keep pressing the start button whilst the machine was already running it won't keep going off. I've sorted it now and got my head round it. I've used a ABB CT-WBS timer. Basically you will have to hold in the start button to supply the timer, this will then sound the alarm for "X" amount of time and then when the timer has switched it will start the machine and you can release the button. From a safety point a view its even better because it gives you chance to stop the machine before its started.
 
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Old 11-17-14, 07:14 PM
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I've just realized this will set the alarm off every time the button is pressed.
 
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Old 11-17-14, 07:55 PM
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Sorted. Output signal to the green LED on the start button stays on only when machine is running. I will use that signal to energize a relay which will sit between the button and timer and wire it into NC
 
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