One buzzer for multiple faults.


  #1  
Old 10-17-19, 08:59 AM
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One buzzer for multiple faults.

So I was drawing a schematic for the panel Iím putting together for some pumps.

i have 3 pumps and two overflow float switches and id like a failure on any of the pumps OR a connection on either of the floats switches to trigger a buzzer.

at first I was thinking I could just connect the floats and the normally open contacts on the overload relays together and to the buzzer but I realized if I do that, one fault would cause all the fault indicator lights to come on which would defeat the purpose of having individual indicator lights.
 
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Old 10-17-19, 09:14 AM
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If you want individual indicator lights then you need individual wires from each switch. If you want one buzzer for all of then then you want a 2 contact relay for each one. One contact turns on the light and the second contact turns on the buzzer.
 
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Old 10-17-19, 09:36 AM
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You need to provide additional info. What kind of pump failure (loss of power, loss of flow)? What kind of float switch failure (since float switch operation results in contacts being open or closed, not easy to detect failure)? What are the overload relays monitoring?
 
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Old 10-18-19, 07:22 PM
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4 pumps, 1 automatic, 3 controlled by contactors and level control relays. The level control relays are simple NO switches which sends power to the NC contacts on the overload relay which in turn is connected to the coil on the contractor.

I want the alarm to trigger for any of the 5 following faults.

Overflow conditions in two tanks as indicated by two float switches (completely independent of the motor controls, these are only to detect overflow)

OR the overload relay on any of the 3 pumps tripping which, if I understand correctly, can be detected by using the NO contacts on the overload relays which close with an overload.
 
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Old 10-18-19, 07:28 PM
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Here is a partial drawing of the plan, note I don't actually know the correct electrical symbols so I did the best I could. I think everything is correct except for the lights and buzzer alarms. It was when I was finishing the drawing and connecting them all together that I realized that if I wired all the fault lights to the buzzer then any of the lights coming on would cause all of them to come on

https://photos.app.goo.gl/eHVtQSpNM6ZWEoFH9
 
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Old 10-19-19, 06:40 AM
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So Joed's mention of relay's made me think, Is there any way I could get away with one or two? They have 4PDT relays that aren't that big but I'm not sure how I could use the 4 poles to help.

Having 5 relays seemed originally like it would take up more space than I had but last night I was browsing online catalogs and came across some low profile SPST relays like this



And that got me thinking, what if each warning light circuit turned on one of the relays which the connected the alarm? That might work right?
 
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Old 10-19-19, 07:09 AM
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Hi, 3 pumps in different tanks?
Geo
 
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Old 10-19-19, 08:02 AM
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4 pumps 4 tanks but 2 pumps are alternated to move from one of the tanks to the another while the last two tanks have one pump each which empty to street and sewer.

Tank 1, sewage. Pump driven by drive shaft connected to 3ph motor. Faults to be indicated: overload, on motor, overflow in tank.

tank 2, rainwater, fully automatic submerged pump (no contactor). Faults to be indicated, overflow.

Tank 3, cistern; Tank 4, pressure tank. 2 external pumps. Faults to be indicated, motor overload on either.
 
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Old 10-19-19, 08:41 AM
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just a quick stab at this: all the NO overflow switches can be connected in parallel; ending with only a single pair. More difficult may be the overloads/heaters. Although i recall there is a uncommitted contact from each, it won't detect an overload from simply being turned off. I suspect this job would require an additional relay for each, powered by the coils, then feeding thru the existing aux contacts.
 
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Old 10-19-19, 06:03 PM
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Hi, I would think that float switches are all that would be required, if a motor OL trips the tank would fill to a point and trip the float switch, what difference dose it make what caused the pump to quit, it will have to be investigated anyway.
Geo
 
 

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