Air Comp.Duplex W/Auto Alternation Diagram
- Thread starter gw92109
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mdshunk
Senior Member
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- Right here.
You need a diagram, basically, for a "pump alternator"? Or a "lead lag controller"? I'm not sure if you just want to alternate them so just one or the other runs, or have one start first, then the other second if the first compressor doesn't keep up?
chris kennedy
Senior Member
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- Miami Fla.
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- 60 yr old tool twisting electrician
gw92109 said:
Welcome to the Forum. This is where a pic or two would be handy.
gar
Senior Member
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- Ann Arbor, Michigan
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- EE
080421-2120 EST USA
gw92109:
Is your logical goal as follows:
1. A flip-flop circuit ( a bi-stable device) determines which pump can turn on. We will start with the flip-flop allowing pump A to function. Pump A turns on at its low pressure threshold. While pump A is on pump B is inhibited from being turned on by the state of the flip-flop.
When pump A reaches its high pressure threshold it turns off, but also this trailing edge triggers the flip-flop to change state. Now pump B will be allowed to start at its low pressure threshold, and pump A will be inhibited from turning on.
When pump B reaches its high pressure threshold it turns off, but its trailing edge triggers the flip-flop back to its enable pump A state.
This logic does not provide a means to have both pumps on at once, but will alternate useage.
2. To add to the function of (1) above you need to define how the system would need to work. For example: you might use 1 pressure switch for both pumps. If after X seconds the pressure is not above the low limit, then the second pump is turned on.
This is much more complex. Ideally you would use an electronic pressure gage and a small PLC to do this type of operation.
Which of these describes your question?
.
gw92109:
Is your logical goal as follows:
1. A flip-flop circuit ( a bi-stable device) determines which pump can turn on. We will start with the flip-flop allowing pump A to function. Pump A turns on at its low pressure threshold. While pump A is on pump B is inhibited from being turned on by the state of the flip-flop.
When pump A reaches its high pressure threshold it turns off, but also this trailing edge triggers the flip-flop to change state. Now pump B will be allowed to start at its low pressure threshold, and pump A will be inhibited from turning on.
When pump B reaches its high pressure threshold it turns off, but its trailing edge triggers the flip-flop back to its enable pump A state.
This logic does not provide a means to have both pumps on at once, but will alternate useage.
2. To add to the function of (1) above you need to define how the system would need to work. For example: you might use 1 pressure switch for both pumps. If after X seconds the pressure is not above the low limit, then the second pump is turned on.
This is much more complex. Ideally you would use an electronic pressure gage and a small PLC to do this type of operation.
Which of these describes your question?
.
mdshunk
Senior Member
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- Right here.
Not really. Pump alternators and lead-lag controllers are off the shelf items. Just need to know which one he needs.gar said:
quogueelectric
Senior Member
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- new york
He is looking for a simple alternator switch where the alternator exercises both motors equally and if either pump A or B cannot deliver the desired load it turns both pumps on. I am certain you could google the setup you desire and you will be able to pdf a wiring diagram. Either sump pumps or air compressors this is the most common application by far.
mdshunk
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- Right here.
If that's the case, that's just a varition of lead/lag. Lead lag with leading alternator. http://books.google.com/books?id=3M...5ynbAnc&sig=Mo1YQIhlRD7EKgZSeOQrwaRI2Yo&hl=enquogueelectric said:
quogueelectric
Senior Member
- Location
- new york
No lead lag is usually used in boiler sequencing panels alternator switches are strictly ABABABABABABABABABABABAB Usually sump pumps or compressors. Unless demand is not being met by one motor then both come on to catch up the goes right back to original function.mdshunk said:
mdshunk
Senior Member
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- Right here.
Maybe in your experience. Lead-lag controllers are sold by all the major air compressor manufacturers and branded with their brand name, if you want to buy them from them. You can get either manual lead-lad selection (actually the switch is typically labeled "lead", "lag", and "standby"), or alternating leading selection. With the alternating lead-lag, each call for more compressed air, a different compressor will start, and the one that started first the last time will be lagging. The lagging one can start on either time or additional pressure drop. The next cycle, the one that lagged last cycle will lead this time.quogueelectric said:
quogueelectric
Senior Member
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- new york
Must be a NY thingmdshunk said:
mdshunk
Senior Member
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- Right here.
Maybe! :grin:quogueelectric said:
With the "controls" the OP lists, I'm guessing they just set each pressure switch a couple pounds different and use the SPDT relay to assign which pressure switch went with which compressor for a primative manual lead-lag selection. One of those deals where each day or each week the maintenance department flipped a switch to toggle the relay. Who knows, though? There's a million and one ways to do lots of things.
gar
Senior Member
- Location
- Ann Arbor, Michigan
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- EE
080421-2151 EST USA
Marc:
If you have a normal pressure switch on each pump, then I assume this has one pole.
For method (2) If there is only one pole on the pressure switch, then you could use one machine's pressure switch as the on-off function of both pumps thru the alternating circuit. Use the other pressure switch set to trigger at a slightly lower low threshold to operate a relay that forces both pumps on. If this over-ride pressure switch had two normally closed contacts, then the relay would not be needed. Is something like this in the stock alternating controls?
With this logic on startup both pumps would run together and after initialization alternate until demand required both pumps.
Logically if you expect both alternation normally and the additional function of meeting greater demand than one pump, then there needs to be a means to differentiate the two conditions.
.
Marc:
If you have a normal pressure switch on each pump, then I assume this has one pole.
For method (2) If there is only one pole on the pressure switch, then you could use one machine's pressure switch as the on-off function of both pumps thru the alternating circuit. Use the other pressure switch set to trigger at a slightly lower low threshold to operate a relay that forces both pumps on. If this over-ride pressure switch had two normally closed contacts, then the relay would not be needed. Is something like this in the stock alternating controls?
With this logic on startup both pumps would run together and after initialization alternate until demand required both pumps.
Logically if you expect both alternation normally and the additional function of meeting greater demand than one pump, then there needs to be a means to differentiate the two conditions.
.
gar
Senior Member
- Location
- Ann Arbor, Michigan
- Occupation
- EE
080422-0830 EST USA
gw92109:
The following web site pages may answer your question. This will partly depend upon how the Furnace MCC works.
http://www.symcom.com/documentation/inst/html/II-50R-400-ALT/II-50R-400-ALTindex.html
http://www.symcom.com/products.asp?cat=53
Note: in the circuit diagram shown you replace the float switches with your pressure switches. The optional High Level Float switch should be a pressure switch with the same hysteresis as the Main control switch, and adjusted so its low trigger point is below the low of the Main pressure switch.
This will not keep both pumps on until the high pressure trigger of the Main is reached, but guarantees that the "High Level Float" pressure switch is reset.
Extra logic is required to keep both pumps on until the Main high pressure threshold is reached.
I was not able to do a Google search for Furnace MCC and get anything useful.
.
gw92109:
The following web site pages may answer your question. This will partly depend upon how the Furnace MCC works.
http://www.symcom.com/documentation/inst/html/II-50R-400-ALT/II-50R-400-ALTindex.html
http://www.symcom.com/products.asp?cat=53
Note: in the circuit diagram shown you replace the float switches with your pressure switches. The optional High Level Float switch should be a pressure switch with the same hysteresis as the Main control switch, and adjusted so its low trigger point is below the low of the Main pressure switch.
This will not keep both pumps on until the high pressure trigger of the Main is reached, but guarantees that the "High Level Float" pressure switch is reset.
Extra logic is required to keep both pumps on until the Main high pressure threshold is reached.
I was not able to do a Google search for Furnace MCC and get anything useful.
.
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