Alternating Lead/Lag Compressor Control

[Mr onetwo]

Here is a thread on the 2 new compressors I bought recently https://www.garagejournal.com/forum/threads/thoughts-on-my-new-compressor.518344/
I am looking for some opinions on how to wire these up in a sort of lead/lag configuration so that they will alternate when air draw is at a normal level but both would run when the demand is high...like when I am using my glass bead cabinet.I am sure there is some sort of system available to do this but I am looking for an affordable hopefully simple approach. The installation instructions call for 25 amp time delay fuses and 14ga conductors.Any thoughts are appreciated.

 

[DeeKay]

Are you able to adjust the load pressure on these or is that factory set? I see there's a 4-20mA transducer instead of an actual pressure switch.

 

[Mr onetwo]

you can, but that will not alternate them to equalize run time

 

[Firebrick43]

Mini HMI/PLC's are quite affordable now but you are not going to get simple except to do it manually.

On the panel put a 3 position switch,

Compressor 1, Compressor 2, and Both.

If you do want to go with a PLC, mini's with enough power can be purchased for under 150 dollars without issue. The Ladder logic would be very simple due to the way the compressor control is already set up, but it would still take some work in learning.

You would only have to hook the remote start pins to the PLC to control, and have an internal timer to log a count for every 15 min of run time.

 

[dogdog]

Would be interesting how you would define heavy usage.

 

[txvwnut]

Look at the flip-flop switches on dual pump compressor setups. When the pressure is low enough it will run both pumps at once but under normal usage it will alternate between the two pumps.

 

[Firebrick43]

Look at the flip-flop switches on dual pump compressor setups. When the pressure is low enough it will run both pumps at once but under normal usage it will alternate between the two pumps.

Problem is that the KTC compressors shown above don't have mechanical pressure switches to start/stop the compressor. They have a pressure transducer that talks to the microcontroller and depending on the parameter setting.

I guess you could install two separate air pressure switches (lead and lag) and use a time mark alternating controller and the controller just complete the circuit between Pins I and REM on the microcontroller. But then you might have alarms/errors with the microcontroller as the mechanical switch my cut before the programmed set point on the microcontroller. or the controller could go into standby and shut down but the mechanical switch still hasn't cut and therefore it wont flop to the other compressor but keep running that specific compressor. I really don't see that as a good idea.

 

[mm08822]

Here is a thread on the 2 new compressors I bought recently https://www.garagejournal.com/forum/threads/thoughts-on-my-new-compressor.518344/
I am looking for some opinions on how to wire these up in a sort of lead/lag configuration so that they will alternate when air draw is at a normal level but both would run when the demand is high...like when I am using my glass bead cabinet.I am sure there is some sort of system available to do this but I am looking for an affordable hopefully simple approach. The installation instructions call for 25 amp time delay fuses and 14ga conductors.Any thoughts are appreciated.

you can, but that will not alternate them to equalize run time

A lead/lag arrangement typically makes 1 unit the primary runner and the second only handles the peak needs. The first unit sees the majority of the wear/run time.
Alternating the units, puts even wear on each. Some equipment management practices disagree with having both units wear out at the "same time". It is better to have one in the "spare back-up" position or in this case, much lower run time hours.

The easiest way for you to stage one lagging the other is to simply adjust the pressure switch cut-in/cut-out setpoints differing between the two as previously mentioned. This eliminates interconnection between the two units, a selector switch, etc. Each remains self-contained and as portable as when they came from the factory. I don't see an easier solution than this. Everything else makes a mess of stand-alone equipment, IMO.

 

[Norcal]

A Furnas alternating relay might fit the bill, they are rather spendy but this one on eBay is a little cheaper. Furnas Electric was bought by Siemens, & they sold parts of the product line to Hubbell, including this relay.

Furnas 47AB10AF Alternating Relay Single Pole 10A 110/120VAC Coil SPDT 783087082816 | eBay

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