# air compressor 15hp



## garfield (Jul 30, 2009)

I can sell you a soft starter that'll limit the inrush.


----------



## noarcflash (Sep 14, 2011)

does it replace the factory packaged Ingersoll Rand Magnetic starter? or is it in addition ?

I know some of them need programming, and a configuration. Is this a simple install ?


----------



## garfield (Jul 30, 2009)

noarcflash said:


> does it replace the factory packaged Ingersoll Rand Magnetic starter? or is it in addition ?
> 
> I know some of them need programming, and a configuration. Is this a simple install ?


It replaces the starter. Motor protection etc. is all internal. As far as setting the parameters I can do that before shipping. I would need the motor nameplate data and your service voltage.


----------



## A Little Short (Nov 11, 2010)

noarcflash said:


> I recently installed a 15HP Ingersoll Rand Air Compressor. Fully packaged unit. came with motor starter, and everything. nice compressor.
> 
> I ran #4's, and it runs nice. The problem is the startup in-rush current. it's about 400-500 amps in-rush.  The breaker in the sub panel handles it, the #4's handle it fine. The sub panel is fine.
> 
> ...


I don't think a 15HP compressor should make the bus bars vibrate. I believe I would check the bus and related parts in the panel. That may not be it but it wouldn't hurt to check the panel, IMO.


----------



## noarcflash (Sep 14, 2011)

after the inital install, you could hear the wires banging against the EMT on startup. So we twisted the wires in the EMT as tight as possible, and then we zip tied the wires in the sub panel every few inches. That solved most of the problem.

Now the only remaining vibration is in the main service entrance panel. But that requires a space suit inspection under load......


----------



## dronai (Apr 11, 2011)

What size CB is on that ? Because of the start up inrush.


----------



## noarcflash (Sep 14, 2011)

Either 80 or 100. don't remember. But the in-rush is only a few seconds. The breaker has never tripped.


----------



## 10492 (Jan 4, 2010)

Voltage drop?


----------



## noarcflash (Sep 14, 2011)

With the #4 wire, there is no voltage drop, as it's only 40-50 feet from the panel. I could/should have used #6 and that would have limited the inrush current.


----------



## 10492 (Jan 4, 2010)

noarcflash said:


> With the #4 wire, there is no voltage drop, as it's only 40-50 feet from the panel. I could/should have used #6 and that would have limited the inrush current.


How far is the sub panel, from the main panel, and what wires feed the sub?


----------



## 10492 (Jan 4, 2010)

240V Single phase unit?

That's 10X the running current under no load.

Is this normal?


----------



## garfield (Jul 30, 2009)

While I can provide you a soft start that will limit inrush current this seems odd for that size service to make any noise starting that compressor.


----------



## noarcflash (Sep 14, 2011)

Dnkldorf said:


> How far is the sub panel, from the main panel, and what wires feed the sub?


 
#4 feed the compressor 40 feet
#2 feed the sub 10 feet from the main service entrance panel.
the main is parellel feeds 100' from the pad mount. 600amp main


----------



## noarcflash (Sep 14, 2011)

garfield said:


> While I can provide you a soft start that will limit inrush current this seems odd for that size service to make any noise starting that compressor.


yes, quote me on a soft start kit please. 208y. the motor is rated 200 volts.

ingersoll does not make it, it has to be engineered and built.
a contactor, an OL relay, and whatever else makes it soft start. It has to intergrate with the low oil switch, and the air switch, which is all wired into the magnetic starter.


----------



## noarcflash (Sep 14, 2011)

maybe the unloader is not working, and the compressor is starting against a full cylinder of air.


----------



## varmit (Apr 19, 2009)

I would agree, it sounds like the motor is starting under load. Either the compressor is not unloading or, if this is a single phase unit, the capacitor could be weak. Does the motor pull about nameplate current after starting? If the current is high while running, there could be mechanical problems with the motor or compressor. Just because something is new does not mean much any more. I have new things that are "bad out of the box" all of the time. 

Another possibility could be a very undersized utility transformer. This would cause a severe voltage drop on start-up, causing a high current draw.

I would check the current on each line to the motor, on start-up. They should be within a few percent of each other. Also, check each phase, at the breaker for the compressor, for voltage drop on starting.


----------



## noarcflash (Sep 14, 2011)

if the pad mount was too small, the lights would dim on startup. there is no capacitor. it's a 3phase Baldor motor.


----------



## 10492 (Jan 4, 2010)

So this is a 208V 3 ph, 15HP compressor, pulling 4-500 Amps at start-up?

That don't sound right.

Nameplate running load around 32A?


----------



## noarcflash (Sep 14, 2011)

40 running amps... give or take. 
Baldor has a 200 volt rated motor for 208 services. SO maybe the current is a little higher than a 230 motor.


----------



## 10492 (Jan 4, 2010)

I ain't great at this kinda stuff, but 500A seems real high for a 15hp 3 phase motor for start up.

LRC for a 20HP 3 phase 230V motor is 290A.


----------



## Jlarson (Jun 28, 2009)

noarcflash said:


> 40 running amps... give or take.


I really don't see a problem here, besides the fact the customer doesn't like the noise. FLA on that motor at 208 is somewhere in the neighborhood of 46 amps and new high efficiency motors can easily have starting currents 8 or 10 times their FLA. 

Sounds like your service is stout enough to handle it since they aren't complaining about light dimming (they aren't right?). If the noise is bothersome sell them the soft start like garfield recommends.


----------



## 10492 (Jan 4, 2010)

Scratch my calcs, I am doing something wrong.


----------



## 10492 (Jan 4, 2010)

Jlarson said:


> Iand new high efficiency motors can easily have starting currents 8 or 10 times their FLA.


Learn something new everyday.......


----------



## CheapCharlie (Feb 4, 2011)

noarcflash said:


> With the #4 wire, there is no voltage drop, as it's only 40-50 feet from the panel. I could/should have used #6 and that would have limited the inrush current.


How do you figure that a smaller wire will limit inrush current? Just curious.


----------



## noarcflash (Sep 14, 2011)

CheapCharlie said:


> How do you figure that a smaller wire will limit inrush current? Just curious.


The impedance of the wire. Less current carrying potential. less fault current potential on a dead short. Every wire has impedance depending on the size...... and don't ask me to go through the calculations :no:

I know a dead short on a main service can exceed 20,000 amps. The only limiting factor is the wire guage.... before a breaker trips.


----------



## frenchelectrican (Mar 15, 2007)

Noarcflash.,

Is this compressour is a dual run type or single type which I mean like it designed to be contionous run or on / off function type or both ?

I know new high effeicy motour will draw more current during start up as someone else did mention.

And did you look at the nameplate to look for code letter that should able tell you what the KVA per HP at locked rotor modé it will tell you what letter it will inprint on the plate. A tip here.,, If you see letter B then you know it pretty high KVA per HP if you see letter " D " it will be lower KVA than letter " B " is.

BTW for 15 HP @ 200 volts triphasé will draw about 40 to 45 amp depending on motour design { only with induction motour only. with sychronous motour it will read lower }

Soft start will help a bit to reduce the current drawage during start up useally limited to 3 to 4 X of running amps.

Oh yeah did you break in this compessour correct way ? if not break in properly somecase it can cause hard start or high starting current { I get them once a while but not too often }

Merci,
Marc


----------



## noarcflash (Sep 14, 2011)

I love the French/English accent.
It was broken in correctly, which is just running it unloaded, so it doesn't build air pressure for an hour.

it's an on/off type, where it cycles on/off all day long. At least 100 times per day.

I have to look at the name plate. not on job site now.


----------

