5 horsepower single phase compressor wire and breaker sizes

[mburrus]

to the real electricians here...

i am building a compressor with a real 5 hp 240v single phase motor... a baldor L1430T. ive never dealt with large motors... i usually dont go above a horse and a half.

i am using an allen bradley 709 starter size 2 with N38 heaters... motor is rated at 20.6a at 230v fla. service factor 1.15.

what wire size do i need to run, and what should i breaker it at, for proper coordination with the starter? i know over rating gets kind of funny with motors, which is why i am asking. is #10 and 30a ok, or do i need to bump up to #8 and 40/50a? wire length will be under 50'.

 

[wyliesdiesels]

Theres numerous threads on here with the same size HP motor and correct wire gauges.

Wire for motor circuits is sized at 125% of NEC table FLC.

For 5HP this means 35a rated wire- either #8/2 NM-b or #10 THEN in pipe.

The breaker can be sized maxed 250% NEC table FLC.

A 30a breaker would be fine.

U will need a disconnect at compressor if further than 50' from and not within sight of panel.

 

[mburrus]

panel will be line of sight... but i may install an air conditioner disconnect on the wall...

thanks for the info

 

[nsula_country]

i am using an allen bradley 709 starter size 2 with N38 heaters... motor is rated at 20.6a at 230v fla. service factor 1.15.

You are using one of the best starters made IMHO... A-B Bulletin 509 and 709 are a tank! I think 709 is obsolete now and 509 is current model... Anyway, good choice. Table says N38 is 20.5 amp, seems you sized that correctly.

CT

 

[matt_i]

If you use a disconnect, make sure it has a 5hp @ ~230vac rating. I recall one with around a 30A resistive load rating but looking into the literature for motor apps, it only had a 1.5hp rating.

 

[mburrus]

nulsa, thanks for the confirmation. we had it sitting on the shelf at work, there were 2 of them, i took the one that was new, but not in the package. they were covered in a thick layer of dust too... lol that i know of, we dont still have any equipment out there that used those starters, so they would be likely unused forever. they were in the mezzanine, which is kind of the storage area for really really old parts.

got a lot of 5 heaters on ebay for $17 shipped... so, not too bad in my opinion!! i just need to come up with an enclosure.

i am planning on doing PLC control for the compressor, so i can have easily changable pressure points... i will use a 4-20ma pressure transducer to send the data to the PLC. but using an old school pressure switch as a backup to shut down the compressor in the event of a plc failure.

 

[mm08822]

nulsa, thanks for the confirmation. we had it sitting on the shelf at work, there were 2 of them, i took the one that was new, but not in the package. they were covered in a thick layer of dust too... lol that i know of, we dont still have any equipment out there that used those starters, so they would be likely unused forever. they were in the mezzanine, which is kind of the storage area for really really old parts.

got a lot of 5 heaters on ebay for $17 shipped... so, not too bad in my opinion!! i just need to come up with an enclosure.

i am planning on doing PLC control for the compressor, so i can have easily changable pressure points... i will use a 4-20ma pressure transducer to send the data to the PLC. but using an old school pressure switch as a backup to shut down the compressor in the event of a plc failure.

I'm all for PLC's and been using them for years, but why overly complicate this basic control scheme? What extra features do you plan to get out of it?

Make sure you have a mechanical pressure relief as a backup regardless of your control method because with proper component failure, you could have a big problem brewing (Pun intended)

 

[mburrus]

because im an engineer and i like to complicate things... lol

i want control available over my web accessable home automation system... i am planning on having a standard pressure switch wired im series with te overload, so if i exceed 170 it will drop out the contactor...

there are also popoff valves... and the tank is rated to 300, 1/4" walls and domes

 

[mburrus]

it is also going to control a motorized ball valve tank drain and possibly one to shut off the air to the shop lines... schedueled time of day starts (build pressure on saturday and sunday mornings, at 4pm so its ready when i get home from work, etc)

 

[nsula_country]

nulsa, thanks for the confirmation. we had it sitting on the shelf at work, there were 2 of them, i took the one that was new, but not in the package. they were covered in a thick layer of dust too... lol that i know of, we dont still have any equipment out there that used those starters, so they would be likely unused forever. they were in the mezzanine, which is kind of the storage area for really really old parts.

got a lot of 5 heaters on ebay for $17 shipped... so, not too bad in my opinion!! i just need to come up with an enclosure.

i am planning on doing PLC control for the compressor, so i can have easily changable pressure points... i will use a 4-20ma pressure transducer to send the data to the PLC. but using an old school pressure switch as a backup to shut down the compressor in the event of a plc failure.

I'm an Automation Controls Engineer. I see where you are going with this project! When you said A-B contactor, I assumed you were in industry. I have access to old inventory like that too. Keep us updated on the PLC controlled compressor, or provide link to build thread!

CT

 

[mburrus]

alright! i didnt think to do a build thread, but i just may... my shop is still not finished, but its getting there... but i am noodling around with various projects in the meantime... cant keep a busy brain down.

i am also having health issues right now (no exact diagnosis yet, but some signs are pointing to lyme disease) so work is progressing slowly, as i have energy and ability.

i am actually a protection and control field engineer for a power utility. i am playing with PLCs for fun on my own time... i have a "home automation system" based off of a red lion data station plus web based hmi, and some advantech adam remote io. for plcs i am playing with automation direct click series.

 

[matt_i]

Unless you do heavy sandblasting you could also have a timer-on delay where you force a shutdown if the compressor has run significantly longer than the time needed to pump up the tank from zero air. Like if a check fails or you drop a valve or the v-belt shreds, or some obtuse failure mode that basically is going to run the motor and/or compressor until someone notices and shuts it off.

Off/auto/manual selector where "manual" could bypass the PLC and run on original P.S.-only configuration and put off going online with the ladder until later, want to inflate a tire now to get to work and don't have time to go online and figure out why there's no air. Off for vacations/trips where it won't need to run.

Complexities are endless

 

[nsula_country]

Unless you do heavy sandblasting you could also have a timer-on delay where you force a shutdown if the compressor has run significantly longer than the time needed to pump up the tank from zero air. Like if a check fails or you drop a valve or the v-belt shreds, or some obtuse failure mode that basically is going to run the motor and/or compressor until someone notices and shuts it off.

Off/auto/manual selector where "manual" could bypass the PLC and run on original P.S.-only configuration and put off going online with the ladder until later, want to inflate a tire now to get to work and don't have time to go online and figure out why there's no air. Off for vacations/trips where it won't need to run.

Complexities are endless

I had planned an Off/Auto/Hand for my compressor project.

Off is OFF???

Auto would be pressure switch.

Hand would be unloader at pressure, continuous motor run.

No PLC... But my brew tower project includes a PLC and HMI..

CT

 

[sberry]

I just got to wonder, what would be the advantage of 4 pressure points? Someone went to great effort to make the machine foolproof to start with, simple, breaker, wire to machine. I spose if a guy works at it can defeat all the engineering went in to it.

 

[bczygan]

I just got to wonder, what would be the advantage of 4 pressure points? Someone went to great effort to make the machine foolproof to start with, simple, breaker, wire to machine. I spose if a guy works at it can defeat all the engineering went in to it.

Engineers just love controlling and measuring things.

If they could, they would control things from beyond the grave and from other dimensions and universes!

And one of these guys is an Engineer and a HAM, which is even worse!

Bill AA8MF

 

[RonRock]

Where can a guy that knows nothing about PLC's go to begin learning?

 

[laser3kw]

because im an engineer and i like to complicate things... lol

It's what we do
Instead of a motorized ball valve, use a standard solenoid valve. have the plc open the valve for "X" seconds (then close) when the pump is started. That will purge any moisture automatically every time it cycles. I had that setup on a compressor, but it used a relay with a delay timer and a solenoid valve.

 

[nsula_country]

Where can a guy that knows nothing about PLC's go to begin learning?

Google. There are some forums that discuss PLCs. Mr PLC is one. Also there are websites with free info on how ladder and function block logic works.

I have not personally checked out the Automation Direct controllers.

Personal experience is Allen-Bradley RSLogix 5, 500, 5000, Connected Components Workbench, (micro 800 and Compact HMI)PanelBuilder32, FactoryTalk View Studio, RSNetworx DeviceNet and ControlNet, RSLinx.

Also Siemens 505, S7-200, S7-300, Wonderware, and a slew of various mfg servo drives, VFDs, Fanuc Robotics, Fronius welding power supplies, PID controllers and valves, torque spindle controllers and CNC mills...

Sure I forgot a few...

Ct

 

[mburrus]

matt, i was toying with that idea as well... hand would be a standard pressure switch and start stop button, auto would be plc, and off would be off. i would have to work out the wiring for it all...

bczygan, i am an engineer and a ham as well... ki4gqo. the two really go part and parcel, if youre really in to it. most of the guys at work are only there for a job, they dont geek out on this stuff like i do.

laser, i have been having trouble finding a solenoid valve rated to 175-200 psi... everything is 120...145... but a solenoid valve would be my preference for a tank drain. the way i have the program set up (for now... early stages) is to drain the tank for 5 seconds every 5 starts, if the pressure at start is over 120psi (dont drain the tank if starting from 0, etc). im sure i will change some of those parameters as a result of operating experience. i would still use a motorized ball to shut off air to the shop piping (incase i have a leaky fitting somewhere, etc, so that i dont dump the tank every night)

ron, i am teaching my self. i went with the automation direct CLICK series because they are relatively full featured, VERY CHEAP, expandable, and the software is free!! you can do some googling as nulsa said, for the basics. i am OK with ladder logic, i am used to looking at hard relay contact style prints that more or less mimic the ladder logic, but i prefer digital logic to set up a PLC... the click series software does not have a functional block diagram mode, which is much prefer. the idec smart relays software does have block diagram, but those smart relays have no communications capability, and i need at least one modbus port.

 

[sberry]

I thought I heard most all of it but a guy learns something new every day, software for air comp. Would never thunk of it. Looks like we skipped over air comp 101 and went right to the big time.

 

[matt_i]

Don't forget you can always use a small air cylinder to open and close a traditional teflon-seat ball valve via the quarter-turn handle (don't forget flow controls). Then you can buy proxes or reed switch "cylindicators" to confirm the motion which was just commanded

 

[mburrus]

lol, why not?

compressor is an emglo gtw300t... v4 cyl with 3 cylinders on the first stage compressing the intake of the last cylinder as a 2nd stage... you know the rest of the specs already...

https://www.zgine.com/1058812216.html

 

[nsula_country]

Don't forget you can always use a small air cylinder to open and close a traditional teflon-seat ball valve via the quarter-turn handle (don't forget flow controls). Then you can buy proxes or reed switch "cylindicators" to confirm the motion which was just commanded

Duh! Anytime you have a cylinder, actuator, or other linear/rotary motion you HAVE to have extend/retract/open/closed prox switches or analog feedback!

I've been re-programming an automated welder we recently rebuilt. Proxs, cylinders, flow controls oh my! Welding Power Supplies and Servo drive are EtherNet/IP I/O... Slick! Controller is A-B CompactLogix with A-B PanelView Plus 6 HMI (expensive hardware)!

You have to start a thread when you start this! I haven't used an A-D Click yet.

CT